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4. Drinking Water Quality across Scotland

4A Public Water Supplies in Scotland

Key Facts

Table 4a

*Note that capacities are given for all 'service reservoirs' which includes Break Pressure Tanks, Water Towers and Clear Water Tanks

Public water supplies in Scotland are the responsibility of Scottish Water. In Scotland 83% of water supplies are derived from surface water sources with the remainder being derived from groundwater sources. Water from all of these sources is treated at 335 treatment works before distribution through 1,127 service reservoirs and over 46,942 km of mains. On average, about 2,363 Megalitres (Ml) of potable water is supplied each day to about 99% of the resident population. The remainder of the population are served by private supplies, which are covered in Section 4B of this report.

In 2005 there were 374 water supply zones in Scotland. The number of treatment works and supply zones in Scotland has been steadily decreasing as Scottish Water and its predecessors have developed regional schemes to replace many of the smaller supplies, improving operational efficiency and the quality of water supplied. In addition, the introduction of the Water Supply (Water Quality) (Scotland) Regulations 2001 increased the maximum population allowed in a single water supply zone from 50,000 to 100,000. This enabled Scottish Water to rationalise some of its supply zones in urban areas.

Assessment of Water Quality Compliance

Schedule 3 of the Water Supply (Water Quality) (Scotland) Regulations 2001 sets out the number of samples that have to be taken by Scottish Water from each water treatment works, service reservoir and supply zone every year. The majority of samples in water supply zones are taken from randomly selected consumer taps. The Drinking Water Quality Regulator expects full compliance with the sampling frequencies specified in the 2001 regulations. Circumstances outwith Scottish Water's control can occasionally prevent samples from being taken, but over-sampling is not allowed.

In practice, each sample is tested for several parameters so the text and the tables relate to the number of determinations (tests) made for each individual parameter rather than to the number of samples taken. If Scottish Ministers have authorised supply point sampling for certain parameters, the results for these parameters are recorded for each zone supplied from the point the sample was taken. A single result could therefore be recorded against two or more zones.

The 2001 Regulations set a prescribed concentration or value ( PCV) for 40 parameters in Schedule 1 of the Regulations. In general, to be wholesome, water must not contain a parameter in excess of a PCV; in the case of the hydrogen ion parameter (pH) the value must lie in a range defined by a maximum and minimum prescribed value. Schedule 2 of the Regulations sets values for a further 11 "indicator" parameters. These are not part of the definition of wholesomeness unless a breach of the standard constitutes a risk to health, however Scottish Water is required to investigate any exceedences which occur.

In contrast to the 1990 Regulations, the 2001 Regulations do not enable Scottish Ministers to authorise the relaxation of a PCV. However, where a non-trivial exceedence of a Schedule 1 parameter occurs, Scottish Water can apply for an Authorised Departure, which allows for a temporary departure from the standard while work is undertaken to secure compliance with the Regulations. This process is described in full in Annex C.

It is important to note that the PCV for each parameter that is of health significance is based on World Health Organization guidelines and is set with a wide margin of safety. For parameters that are of aesthetic significance, the standards are generally set well below the level at which water would become unacceptable to consumers. A contravention of a standard is not necessarily indicative that the water is unfit to drink or represents a risk to health.

A contravention of a PCV is of significance because it means that the water supplied at the time the sample was taken cannot be regarded as wholesome as defined by the Regulations. When a contravention is considered in conjunction with other monitoring results, it may indicate that work is necessary in order to meet the high standards set in the Regulations. When considering some contraventions, especially those for lead and microbiological parameters, it is important to remember that the samples have been taken from a consumer's taps and may reflect the condition of the tap or associated plumbing rather than the water in the public supply.

The general rule that any individual contravention of a PCV constitutes a breach of the Regulations and thus causes the water to be regarded as unwholesome, does not apply to the coliform standard at service reservoirs, specified in the 2001 Regulations. The requirement in Table A of Schedule 1 and regulation 4(6), is only breached if 5% or more of determinations carried out over the preceding year contain coliforms.

In addition to absolute PCVs for nitrite and nitrate, regulation 4(d) specifies an additional requirement reflecting the combined concentration of the two parameters, namely that the water satisfies the formula [nitrate]/50 +[nitrite]/3 <1 where the square brackets refer to the concentration of the two compounds in mg/l. An assessment of compliance with this formula was not included in the data presented by Scottish Water to DWQR, however, calculations show that this standard was not breached in 2005.

The term "total coliforms" refers to the parameter listed in Table A of Schedule 1 and in Schedule 2 of the Regulations. It includes all coliform organisms whether faecal in origin or not. In the following sections, the term "coliforms" has been used for the total coliform parameter to simplify the text. The detection of coliforms in a sample is indicative of potential contamination that must be investigated.
The presence of faecal coliforms ( E. coli) in the same sample would indicate that the contamination was of faecal origin. It should be noted that while the Regulations permit up to 5% of samples taken from each service reservoir to contain coliforms, they require that faecal coliforms should be absent in all samples.

Overall Compliance

The drinking water quality results reported by Scottish Water for 2005 show that 345,761 tests were carried out on samples taken from water treatment works, service reservoirs and consumer taps. Of the 153,291 tests on samples taken from consumer taps, 99.56% met the required standard. This is an increase of 0.14% on compliance for 2004. A total of 669 tests gave results which did not meet the standard set out in the Water Supply (Water Quality)(Scotland) Regulations 2001. The largest number of failing samples was for the total coliform and trihalomethane parameters. Further details may be found in Section 4.4.

4.1 Quality of Drinking Water Sources

The 2001 Regulations do not require Scottish Water to sample its water sources, although sampling does take place for operational reasons and to comply with the Surface Waters

Table 4.1a Summary of Data from Water Quality Sampling in Reservoirs and Lochs used for public drinking water supplies

(Abstraction for Drinking Water) (classification) (Scotland) Regulations 1996.

The table shows a summary of selected results from tests carried out on samples taken from loch and reservoir sources in 2005. The data is a combined summary of all the sources that were sampled. It provides an indication of the range of waters Scottish Water is required to treat in order to produce water that complies with the standards set down in the 2001 Regulations.

Some substances, such as iron and manganese, are naturally occurring. Others such as nitrate and pesticides are present because of agricultural activities. It can be expensive to remove these substances from water, however, as the data shows, they are not present in many Scottish sources. This is because most sources in Scotland are derived from upland catchments where agricultural activity is limited.

Table 4.1b Source Water Cryptosporidium Data - 10 sites with the highest mean count

The Cryptosporidium Directions (Scottish Water) 2003 require Scottish Water to sample its raw (or source) waters for Cryptosporidium at all sites that have been designated as high risk. In 2005, a total of 65 raw waters were sampled across Scotland. Positive Cryptosporidium samples were found in all but 23 of these sites. Table 4.1b shows a summary of the data for the whole of Scotland and details the ten sites with the highest average count of Cryptosporidium oocysts in raw water samples. It can be seen that the majority of these are in the North East region, perhaps reflecting patterns of agricultural activity. An appropriate, well optimised treatment process should ensure these oocysts are not present in the final water.

4.2 Drinking Water Quality at Treatment Works

Table 4.2a Summary of Microbiological Tests on Samples Taken at Treatment Works and Comparison with Previous Years

The Regulations require that samples are taken from treatment works and tested for a number of parameters. These include microbiological parameters, order confirm the effectiveness of the disinfection process, and turbidity and nitrite which demonstrate control of other treatment processes.

The table above shows summary results for tests carried out for coliforms and E. coli on samples taken from treatment works in 2005. One hundred and thirty (0.38%) of the samples taken at treatment works in 2005 contained coliforms. This is an increase on both 2004 and 2003. The exact reason for the increase is unclear, but the summary, in Section 5 of this report, of incidents that occured during 2005 shows that the disinfection process at some treatment works is not as robust as it should be. The DWQR expects Scottish Water to work to improve its compliance at water treatment works, both through investment and improvements in operational procedures.

The corresponding figure for E. coli (faecal coliforms) of 51 failures (0.15%) shows an improvement, which is to be welcomed, although the failure rate is not significantly better than the 2001 figure of 0.16%.

Table 4.2b Summary of Nitrite Tests on Samples Taken at Treatment Works

Nitrite is a compound which can form when there is an excess of ammonia in a supply. It is an Indicator Parameter in treated water, and the standard was introduced in order to monitor the effectiveness of the disinfection process, particularly where chloramination is used.

In 2005, 9 samples failed to meet the required standard of 0.1mg/l, representing a failure rate of 0.26%. This is an improvement on 2004, when 12 samples failed. It should be noted that whereas in 2004 the failures were in samples from only two treatment works; in 2005 nine works recorded failures. As these were all single failures which were not repeated, it is unlikely that they represent a significant loss of process control, however this is a trend which will be monitored closely in future years.

Table 4.2c Summary of Turbidity Tests on Samples Taken at Treatment Works

Turbidity of treated water is an important measurement because it can provide an indication of how well the treatment process is removing particulate matter (including Cryptosporidium). It can also provide an indication of the effectiveness of disinfection because it is difficult to adequately disinfect turbid waters.

In 2005 112 samples exceeded the standard, representing 1.25% of samples tested. 14.6% of Scottish Water's treatment works recorded at least one failure of the standard in 2005.

Table 4.2d Summary of 2005 Sample Data for Cryptosporidium in Final Water

Depending on the local risk assessment, Scottish Water's treatment works should have had between 12 and 365 Cryptosporidium samples taken in 2005, with the exact sample frequency being determined by the Cryptosporidium Directions. In 2005, Scottish Water made significant progress to improve compliance with the defined sampling frequencies, following a shortfall in 2004. 10,691 scheduled regulatory samples were taken in 2005 and of these, 728 contained Cryptosporidium oocysts. The number of oocysts detected was generally very low and well below the level at which health professionals would require action to be taken. In 2005, at least one positive sample was recorded at 41.6% of the treatment works in Scotland.

In the Autumn and Winter of 2005, and extensive audit was carried out of Scottish Water Complience with the Cryptosporidium Directions. Whilst there remain a few points requiring further work to achieve full compliance, the DWQR is pleased to report that the majority of requirements have been implemented. DWQR shall continue to check compliance through the annual technical auditing programme to ensure that the Directions are fully integrated with Scottish Water's routine operations.

Further details of Cryptosporidium samples taken may be found in the regional pages in Section 5 of this report.

4.3 Drinking Water Quality in Distribution Systems

The network of water mains, service reservoirs and water towers which carries drinking water from the treatment works to the consumer is known as the distribution system. Regardless of how thoroughly drinking water has been treated, the condition of the distribution system can have a significant effect on the quality of the water passing through it. Cast iron mains corrode and can add particles of iron to the water. Deposits of iron, manganese or aluminium lying in the system, which have accumulated from inefficient treatment processes, perhaps long since replaced, can be stirred up by changes in the flow to cause discoloured supplies.

Service reservoirs which are not maintained in good structural condition can be prone to inward leakage from contaminated surface water. Secondary disinfection is installed at some service reservoirs, but this should only be used where chlorine residuals diminish because the reservoirs are part of long distribution networks. In such cases there may be a need to boost disinfection levels to achieve a disinfection residual at the end of the network. However, it is important that secondary disinfection does not disguise a more fundamental problem with a service reservoir such as compromised structural integrity. Scottish Water adopts a risk based approach to cleaning and refurbishing service reservoirs. The DWQR inspects a selection of structures each year in order to ensure that they are being maintained and operated in a way which minimises any risk to water quality.

The Regulations require that Scottish Water samples every storage point each week it is in operation. Faecal coliforms must not be present in any sample taken from a service reservoir and for total coliforms the requirement is that 95% of samples are clear.

Table 4.3a Summary of Microbiological Tests on Samples Taken from Service Reservoirs and Comparison with Previous Years

Summary results for service reservoirs in 2005 compared to those for previous years show that 0.39% of samples contained coliforms and 0.06% contained E. coli. Both figures represent an improvement on previous years.

OPI( TIM) is a an operational performance indicator which is being used by all the UK drinking water quality regulators to monitor the performance of distribution systems. OPI( TIM) looks at regulatory sample data for turbidity, iron and manganese. These are the three parameters which best reflect the performance of the distribution system and its tendency to cause discoloured water incidents. Turbidity is a measure of the cloudiness of the water and iron and manganese are the two substances most commonly associated with discoloured supplies.

Table 4.3b Operational Performance Indicator ( TIM) in Scotland

Whilst iron in water supplies is commonly derived from the corrosion of cast iron water mains, it may also originate from a poorly performing water treatment works which is failing to adequately remove naturally occurring iron from the raw water. Elevated manganese concentrations always originate from a treatment source. Both compounds may be deposited in distribution systems where low velocities enable them to settle out and accumulate. Such deposits may later be disturbed by changing flows to cause discolouration. OPI( TIM) is also, therefore, a measure of the effectiveness of techniques used by Scottish Water to keep the distribution system clean.

A full description of OPI( TIM), which is derived from the Mean Zonal Compliance for turbidity, iron and manganese, may be found in Annex E.

Table 4.3b shows that OPI( TIM) for Scotland in 2005 was 98.50. This value will be the benchmark for comparison in future years. The table also shows the worst performing zones in 2005, reflected by the lowest OPI( TIM) scores.

Many of the supply zones listed are in the North West and Western Isles, Orkney Islands and Shetland regions. In part, this can be explained by the small populations of many of these zones which means that only a small number of samples require to be taken throughout the year. One failure within a small dataset can have a large impact upon OPI( TIM). This also explains why many of the OPI( TIM) scores are the same. Despite this, there is no doubt that many of these small supplies do allow large amounts of iron to enter the distribution system, usually due to inadequate treatment. The Authorised Departure process (Annex C) provides a formal process by which Scottish Ministers can track failing zones and require Scottish Water to install appropriate remedial measures. Meavaig Western Isles, the zone with the lowest OPI( TIM), was granted an Authorised Departure and should now be fully compliant for iron and manganese.

Several supply zones which feature on the table are in the same area of Dumfries and Galloway. The low score in these zones reflects the failure of the treatment works to remove iron and manganese and the poor condition of the distribution system. The DWQR is monitoring the situation in this area closely.

4.4 Drinking Water Quality at Consumer Taps

Most tests to verify compliance with the regulations are undertaken on samples taken from consumers taps. Sample frequencies are based on the population of the water supply zone. Sample locations are chosen at random within the zone and sampling should be evenly distributed throughout the year.

Table 4.4a Summary of All Tests on Samples Taken from Consumer Taps in Scotland in 2005

*In force for all or part of 2005

The table summarises the results of all samples taken from consumers taps in 2005. The 10 key parameters which are of most significance for drinking water quality are shown first. The remaining parameters are listed alphabetically.

Mean Zonal Compliance has been used for the first time, in common with other UK drinking water quality regulators. This is a simple calculation which reflects the percentage of samples which met the required standard for a given parameter and water supply zone. By taking an arithmetic mean of each zonal compliance across any group of zones or parameters, an indication of overall performance may be provided. A more full description of Mean Zonal Compliance is given in Annex E.

In table 4.4a, the Mean Zonal Compliance ( MZC) is shown for each parameter across Scotland. The Overall Compliance figure for Scotland as a whole is derived by taking the mean of the MZC for every parameter for which there is a numerical standard. In 2005 the Overall Compliance for Scotland was 99.42%. This figure will provide the baseline against which future performance is tracked.

The 10 Key Parameters

Microbiological Parameters

Table 4.4b Summary of Microbiological Tests on Samples Taken at Consumer Taps and Comparison with Previous Years

Out of all the drinking water quality data, the results of microbiological tests carried out on samples taken from consumer taps undoubtedly hold the greatest significance for public health. Table 4.6 shows data from 2005 and the four preceding years for coliforms and E. coli. Both percentage compliance figures for 2005 show a deterioration when compared against 2004 data. It could be argued that the number of samples containing E. coli shows no statistically significant difference between 2005 and the preceding two years, but there is certainly a clear reduction in coliform compliance over the same period.

The reason for the decline in coliform compliance is not clear, although it does mirror a decline in compliance at treatment works. The trend is also visible at a local level, when the data is analysed by Local Authority. There have undoubtedly been a number of water quality incidents reported to DWQR in 2005 which involved failure of the disinfection process or microbiological exceedences which will have contributed to the trend.

Table 4.4c Mean Zonal Compliance for Microbiological Tests by Region

This table shows the MZC for the coliform and E. coli parameters. Both sets of data show that the North West and Western Isles, Orkney Islands and Shetland regions have the poorest microbiological compliance. These areas are also responsible for the majority of the incidents involving disinfection failure reported to DWQR in 2005. It is likely that the trend reflects large number of works with only basic treatment which are currently found in these areas.

Trihalomethanes

As with previous years, the parameter with the greatest percentage of samples exceeding the prescribed concentration or value ( PCV) is Total Trihalomethanes ( THMs). There is a significant improvement on 2004, reflecting the work carried out by Scottish Water to improve its treatment processes. However much work remains to be done to secure full compliance with the THM standard. This will continue to be monitored and regulated via the Authorised Departure process.

Table 4.4d Mean Zonal Compliance for Trihalomethanes by Region

The table shows that the North West area has by far the lowest MZC for THMs, reflecting the large number of works in that area that still do not have a treatment process capable of removing the compounds which form THMS when chlorine is added to the water.

Colour and pH

Compliance with the standards set for these parameters also showed an improvement on previous years, reflecting the improvements carried out on the many small supplies in the North West and on the islands, many of which previously only had basic disinfection. Again, the Authorised Departure process will continue to be used to facilitate these improvements.

Table 4.4e Mean Zonal Compliance for Colour and Hydrogen Ion by Region

The table shows that, despite recent improvements, there remains work to be done to improve treatment processes in the North West and Island regions. The relatively low MZC for colour in the South East area is due to the problems experienced in the Alnwickhill supply, where an increase in raw water colour meant that the PCV was exceeded in many samples taken in parts of Edinburgh in 2005. The problem has now been resolved.

Iron and Manganese

Iron and manganese are significant because they cause discoloured supplies. In common with the other parameters, compliance has improved significantly in 2005, with 1.48% of samples not meeting the standard in 2005 against 2.51% in 2004. Whilst this indicates that progress is being made, the figure is still too high, and consumer complaint data (Section 4.6) shows that, on occasion, many consumers still find the appearance of their water unacceptable.

Table 4.4f Mean Zonal Compliance for Aluminium, Iron and Manganese by Region

MZC for aluminium and is lowest in the North West and, in particular, the Islands. Iron compliance is also low in these areas and, additionally, the South East, where the supply zones around Newton Stewart have poor compliance. The North West and North East have the highest MZCs for manganese.

Table 4.4g Mean Zonal Compliance for Lead by Region

Lead

Although not present in water as it leaves the treatment works, lead can dissolve into water supplies from lead service pipes and internal lead plumbing which is often found in older properties. Whilst not wholly within its control, Scottish Water has a responsibility to ensure that the concentration of lead at consumer taps is as low as possible. This is achieved through plumbosolvency control which reduces the tendency of the water to dissolve lead from lead pipework. In addition, if a consumer replaces their lead plumbing and any lead present in their part of the service pipe, Scottish Water must replace its part of the service pipe if it is made of lead.

Lead compliance has shown little change from 2004 and highlights the work Scottish Water must undertake if it is to meet the tighter standard for lead of 10 microgrammes per litre which comes into force in 2013. DWQR will be working with Scottish Water and monitoring progress made to achieve the tighter standard.

Table 4.4g shows that MZC for lead is highest in the Western Isles, Orkney Islands and Shetland and lowest in the South East. It is likely this is due to a number of factors such as the number of lead pipes present in the region, the tendency of the water to dissolve lead and the extent and effectiveness of any plumbosolvency dosing.

Other Parameters of Note

Ammonium and nitrite recorded a significant number of failures in 2005. Both parameters can reflect either poor control of the chloramination process, which is used for disinfection, or low disinfectant residuals in the distribution system. Many of the nitrite exceedences can be attributed to two supply zones supplied by Marchbank WTW near Edinburgh. The DWQR has obtained assurances from Scottish Water that it is working to resolve the problem in these supply zones and is monitoring progress closely.

There were 10 exceedences of the antimony standard in 2005. This is an unusual parameter to fail the PCV, and the failures were attributed to a small quantity of antimony present in the plastic caps used on sample bottles. The use of these bottle caps by Scottish Water has now been discontinued.

4.5 Summary of Drinking Water Quality Incidents

Scottish Water must inform DWQR of any event at a water treatment works or in the distribution system that could adversely affect water quality, cause concern to consumers or attract media attention. Details of each event are assessed by DWQR and it may be classified as an incident if it was sufficiently serious or had the potential to be serious. Usually, DWQR will request a full report from Scottish Water on the causes and impact of any event classified as an incident, including details of the remedial action taken and actions by Scottish Water to prevent a recurrence. Where appropriate DWQR will investigate further. All events where a boil notice or alternative supplies are issued are classified as an incident regardless of whether a report is requested by DWQR.

Figure 4.5 Drinking Water Quality Incidents in 2005 by Region

In 2005, 42 events were classified as incidents. Of these, 15 resulted in the issue of a boil notice or the provision of alternative supplies following discussion between Scottish Water and the relevant NHS Board. Figure 4.9 shows incidents broken down by region. The greatest proportion of incidents occurred in the North West, reflecting the large number of small works with very basic treatment which are vulnerable to rapid changes in the quality of the raw water. Many of these incidents involved a failure of the disinfection process. Scottish Water is investing significant sums of money to improve the treatment at these sites, and DWQR expects Scottish Water to ensure that staffing and operational procedures are adequate to safeguard water quality.

Much progress was made by Scottish Water last year to ensure that if something goes wrong at a water treatment works, systems are in place to alert the appropriate member of staff of the problem and enable a prompt response to prevent water quality being adversely affected. DWQR has been closely monitoring Scottish Water's efforts in this area, and while progress is being made, there continue to be water quality incidents where problems were not discovered and rectified until it was too late to avoid affecting final water quality. Throughout 2006 DWQR continue to investigate and monitor such situations to ensure Scottish Water's systems are robust and that its response is timely and appropriate when something goes wrong.

Events and incidents will always occur, but there is much that could be done to reduce the number and severity of incidents from current levels. Scottish Water must do more to learn from events and incidents. DWQR will work with Scottish Water to ensure that lessons learned are disseminated across the organisation. Summaries of incidents which occurred in 2005 may be found under the relevant regional pages in Section 5, with more details of selected incidents provided under the relevant local authority pages in Section 6.

4.6 Summary of Complaints About Drinking Water Quality

Scottish Water is required to record details of complaints it receives from consumers concerning drinking water quality. DWQR also receives complaints from consumers. These complaints may be received by telephone, letter or email. Table 4.6a and Figure 4.6b show the number and type of complaints recorded by Scottish Water in 2005. The meaning of the categories is described below:

Appearance of the Water

Discoloured Water

Water with a discernable taint or colour caused by suspended or dissolved matter. Two of the most common causes are a yellow taint caused by dissolved organic matter arising from peat in upland sources and more general orange, brown or black discolouration caused by suspended particles of iron (orange/brown) and manganese (black). Iron discolouration may occur through natural iron present in the raw water passing through inadequate treatment or from corrosion of cast iron distribution mains. Manganese is present in some raw waters and may not be removed if treatment is inadequate.

Aerated (Milky/Cloudy) Water

Water which has a milky appearance caused by tiny bubbles of entrained air which dissolve in the water under pressure but come out of solution at the consumers' tap. A number of causes are possible including burst mains, malfunctioning pumps and throttled consumer stop taps. If air is the cause of the milky water, the cloudy appearance will clear in a glass of water from the bottom up.

Stained Washing

Brown or black staining to clothes washed inadvertently in discoloured water. Staining may also arise from a fault with the washing machine. If clothes are kept damp, the staining may often be removed by gently acidifying with a suitable substance such as citric acid.

Particles in Water

Visible particulate matter in water which is otherwise not discoloured. This can be caused by corrosion of iron mains or deposits of sand, grit or other material which may be present in the main and is re-suspended following a flow disturbance.

Taste and Odour of the Water

Chlorine or Phenolic

Excess residual chlorine or the product of chlorine reacted with phenolic compounds which may be present in household plumbing. Chlorine itself should dissipate if water is stood in the fridge for a few hours and will also not be present after boiling. Phenolic tastes can be more persistent. Common descriptions used by customers include TCP, medicinal, swimming pool, bitter, and chemical. Common sources of phenol include washing machine hoses, tap washers and kettles. British Standard approved plumbing products do not contain phenol and should be used in all plumbing installations.

Metallic

Metallic tastes may arise from an excess of iron, aluminium or other metal dissolved in the water, although normally there will also normally be visible discolouration. Occasionally phenolic complaints may be described as metallic.

Musty or Earthy

Musty or Earthy tastes can arise due to naturally occurring compounds present in raw waters that have not been removed by the treatment process. Geosmin is one such compound commonly implicated. Complaints are more common in the summer months when biological activity is highest - algal blooms in raw water sources are common causes of widespread musty tastes.

Organisms in Water

Complaints of insects or other animals in the water supply. Most complaints arise where an insect has crawled up a tap or is present in the sink. Very occasionally water systems can contain animals which may arise from the raw water, treatment works or within the mains themselves. This is extremely rare, however organisms such as midge larvae ( Chironomid) or water shrimp ( Aesellus) have occasionally been found in domestic supplies.

Table 4.6a Complaints About Drinking Water Quality Received by Scottish Water in 2005

Figure 4.6b Pie Chart Showing Proportion of Consumer Complaints about Appearance and Taste and Odour

The data shows that the appearance of drinking water generates by far the largest proportion of consumer complaints. This is mainly due to complaints relating to discoloured water which accounted for almost 7 complaints out of every 10 in 2005. In the North West it is likely that many of these are due to highly coloured peaty waters where existing treatment is inadequate to fully remove the colour-causing compounds. In other areas the deteriorating condition of old cast iron mains, leading to an accumulation of iron sediment, is most likely to be the primary cause of dissatisfaction. It is expected that Scottish Water will target both causes of discolouration by further investment in improved treatment and the rehabilitation of ageing water mains during the next investment period of 2006-2010.

Taste and odour complaints accounted for 13% of the total. The majority of these were connected to the use of chlorine as a disinfectant. Whilst it is essential that supplies receive adequate disinfection to protect public health, the DWQR expects Scottish Water to monitor the use of chlorine carefully and to use no more than is necessary. The DWQR has set Scottish Water targets to improve the control of the disinfection process at water treatment works.

Figure 4.6c Pie Chart Showing Consumer Complaints in 2005 by Region

Figure 4.6c shows the number of consumer complaints about drinking water quality by region. The South West region is responsible for the largest number of consumer complaints, accounting for almost 50% of the total received in 2005. However this is in proportion to the percentage of the population who live in the South West. The North West and Western Isles, Orkney Islands and Shetland regions have a disproportionately large number of complaints when compared to the population in these areas. The North East region has a slightly smaller share of total water quality complaints than would be expected from the proportion of the population it covers.

4B Private Water Supplies in Scotland

Key Facts for Private Water Supplies in Scotland

Table 4b Key Facts for Private Supplies in Scotland

NOTES:

Category 2 (i) supplies include all supplies serving premises used for commercial food production, i.e. those used for manufacturing, processing preparing or marketing of food and drink(including water) for sale or human consumption on or off the premises.

Category 2 (ii) supplies include all supplies serving commercial camp sites, holiday villages, including properties used for commercial lettings, with changing populations which have been allocated to the classes of supply under Category Two of the Private Water Supplies Regulations (Scotland) 1992 as amended.

Private water supplies serve around 140,000 people in Scotland with many tens of thousands of people using private water supplies as they access services such as tourist accommodation (B&Bs, hotels, etc.) and food outlets. The regulatory framework for private water supplies in Scotland changed in 2006, and the new Regulations will be discussed below. It should be borne in mind that the figures presented in this Report for private water supplies were collated in respect of the former Regulatory regime as set out in the Private Water Supplies (Scotland) Regulations 1992.

The quality of private water supplies is highly variable and in the worst cases can cause significant health problems. Health Protection Scotland ( HPS) estimate that those on private water supplies are at least 10 times more likely to become ill from consuming contaminated water than those on the public supply.

4.7 Private Water Supplies - Regulatory Framework

The New Regulatory Framework and New Approach to Regulations

While the primary driver for legislative change was the revised Drinking Water Directive from the European Commission (Council Directive 98/83/EC, November 1998), other drivers included the World Health Organization ( WHO) Guidelines on Drinking Water Quality (3rd Edition) and the Scottish Executive E. coli O157 Task Force Report of June 2001. The overriding objective of the new Regulations was to ensure the provision of clean and wholesome water to rural communities and rural businesses in Scotland.

The new approach to regulation has been to shift the whole regulatory effort away from "end-of-pipe testing" i.e. testing the water that emerges from a tap, towards a more pro-active approach based around risk assessment, i.e. trying to identify potential problems before they occur and taking appropriate steps to reduce or eliminate the risks such problems pose. Both the WHO and the Task Force Report stress the benefits of carrying out a thorough risk assessment from water source through treatment to the point of consumption rather than just undertaking the more usual and regular monitoring and sampling of a private water supply which provides water quality information at a specific point in time. The Private Water Supplies (Scotland) Regulations 2006 adopt this new approach by incorporating risk assessment as part of the core philosophy underpinning the Regulations.

The 1992 Regulations arose from the 1980 Drinking Water Directive (80/778/EEC) which was " concerned with standards for water intended for human consumption". The 1998 Directive is much more targeted with Article 1 of the revised Directive stating " The objective of this Directive shall be to protect human health from the adverse effects of any contamination of water intended for human consumption by ensuring that it is wholesome and clean". This meant that the informal approach adopted in the 1992 Regulations which simply encouraged relevant persons to maintain and improve supplies would no longer be sufficient. Member States were required to take formal action to ensure that water quality standards met the stringent requirements of the revised Directive.

In November 2001 the Scottish Executive published a consultation outlining a variety of options regarding the future direction of private water supply Regulations. The consultation dealt with generic issues that apply to all private water supplies and issues required to implement the revised Drinking Water Directive on the quality of water intended for human consumption. Many of the comments made by respondents to the consultation were acted upon by the Executive.

One comment was that measures would be required to respond to the financial impact of achieving the public health aims of the new Regulations. These comments were recognised as being legitimate and in 2003 specific provision was made in the Local Government in Scotland Act (2003) for Scottish Ministers to provide financial assistance through grants administered by local authorities and governed by Regulations made by Ministers. In The Scottish Executive's Spending Review 2004 a total of £24 million was identified for the private water supplies Grant Scheme up to March 2008. The Grant Scheme is detailed in the Private Water Supplies (Grants) (Scotland) Regulations 2006.

In addition to the new Regulations for private water supplies and the Grant Scheme the Scottish Executive prepared a detailed technical guidance manual for local authorities and an education and awareness campaign aimed at users of private water supplies. The overall package of new Regulations, Grant Scheme, technical guidance and the education and awareness campaign formed part of a package of measures introduced by Scottish Ministers to assist local authorities and individuals to improve the quality of private water supplies in Scotland. DWQR recognises the benefit of such an integrated package of measures in improving the quality of private water supplies in Scotland and has supported such an approach.

The Private Water Supplies (Scotland) Regulations 2006 - Summary of Main Changes

The new Regulations have a significant impact on larger supplies - defined in the Drinking Water Directive as those providing 10m ³ or more of water a day or serving 50 or more persons, and supplies to commercial or public activities irrespective of their size. These supplies are required to meet the revised water quality standards set by the Directive and are referred to as Type A supplies in the new Regulations. Smaller, "non-Directive" supplies are referred to as Type B supplies in the Regulations.

The new Regulations also amend the Water (Scotland) Act 1980 to place a duty on Local Authorities to monitor larger Type A private water supplies. In relation to smaller non-Directive supplies, local authorities continue to have discretionary powers very similar to the obligations placed on them in the old 1992 Regulations and under the 1980 Act. It should be noted that the primary legislation pertaining to water supplies in Scotland, including private water supplies, remains the 1980 Act.

Small hotels, B&Bs, campsites and self-catering holiday accommodation will be required to ensure their water supply meets the stringent quality standards set by the Regulations. Public or commercial premises will also be required to display a prominent information notice alerting holiday makers and other consumers to the potential risk associated with water from a private water supply. These provisions were recommended in the E. coli O157 Task Force Report of 2001 and DWQR welcomes their inclusion within the new Regulations.

The long-term expectation is that all private water supplies will eventually meet the quality standards set by the Directive. However, until this can be achieved the new Regulations enable local authorities to grant derogations (temporary departures) from the prescribed quality standards provided that " no derogation constitutes a potential danger to human health and provided that the supply of water intended for human consumption cannot otherwise be maintained by any other means". Derogations are strictly time limited: initially for a three-year period, but this can be extended to six years to ensure private water supplies comply with the Regulations. In exceptional circumstances a further derogation not exceeding three years can be issued, but this has to be sanctioned by the European Commission. There can be no derogation in respect of microbiological parameters since these pose an immediate risk to health.

The new Regulations require local authorities to find out the cause of a supply failure and initiate remedial action. Risk assessments are an essential element of effective drinking water quality surveillance and control. local authorities are under a duty to complete a risk assessment for the Type A supplies and to provide information and support to enable owners to complete a risk assessment for the Type B supplies. The completed risk assessment will link these Regulations with the Grant Scheme.

For certain groups of parameters listed in the Directive (the "audit monitoring parameters"), where it can be demonstrated that they have not been present or are unlikely to be present in a specific supply, then these parameters can be excluded from the list of parameters required to be sampled an analysed. This powerful provision will have the effect of ensuring that only those parameters of concern are looked for thereby balancing the two potentially competing requirements of cost-effective regulation and the protection of public health. DWQR welcomes the incorporation of this provision into the new Regulations.

4.7.3 Role of DWQR in Private Water Supplies

While DWQR has no direct responsibility for the enforcement of the Regulations relating to private water supplies, DWQR has the general function of supervising the enforcement of the Regulations by local authorities. DWQR will continue to report on local authority activities in relation to private water supplies under the new Regulations and will introduce a programme of auditing Local Authorities' implementation of the new Regulations from 2007.

4.8 Quality of Private Water Supplies in Scotland in 2005

The results of monitoring to the end of 2005 show 3,255 or approximately 35% of the supplies tested failed to meet the requirements of the Private Water Supplies (Scotland) Regulations 1992. Under these Regulations local authorities had powers to monitor and require improvements in the quality of private water supplies but much was left to the discretion of local authorities to develop and tailor policies to their specific priorities and particular circumstances. This results in varying levels of action in respect of private water supplies from one local authority area to another.

Table 4.8 Summary of Private Supply Returns from Local Authorities

Many of the category one failures related to class F supplies (single dwellings), which local authorities had no obligation to test under the 1992 Regulations. However, test on class F supplies were carried out for many reasons. Some local authorities had long-standing policies of checking all private supplies; others had found that they receive a significant number of requests to carry out tests. These requests can arise directly from the householder or as a result of enquiries from solicitors involved in the sale or purchase of houses with private supplies.

One local authority, South Lanarkshire, reported that they issued 9 improvement notices with respect to private water supplies under the Housing Act, These required improvements to be made, but unlikeimprovement programmes, they did not detail steps to be taken.

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