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Water Supplies in Public Buildings: A Consultation

Annex A

Report to the Scottish Executive Water Services Unit on Compliance of Public Buildings with the new Drinking Water Directive

September 2000

Prepared by
Miranda Jacques-Turner, Bryan Wallis and Ken Deacon
East of Scotland Water, Environment and Quality Regulation Team

Statistical Analysis: Dr Lorna Richardson
Waterway Consultancy

Compliance Costs: Dr Gamini Karunaratne
Waterway Consultancy

Chemical and Microbiological Analysis: ESW Scientific
NoSWA Turriff Laboratory

Executive Summary

The new Drinking Water Directive 98/83/EC requires that water supplies in public buildings such as hospitals, schools and restaurants are obliged to meet new water quality standards. Unlike domestic properties, there are no exemptions from the effects of internal plumbing.

Public buildings in Scotland, in these three broad categories, were selected at random and sampled over a period of 10 weeks during June, July and August 2000. A total of 303 public buildings were visited and 572 samples taken. In addition, data on age and type of property and plumbing installation was collected.

Samples were analysed for selected microbiological and chemical parameters that were likely to be affected by internal plumbing. Information on the quality of water actually supplied to these premises is available from Water Authority zone information reports.

The results from the buildings sampled indicated a high level of compliance and that the main problem will be in achieving the new lead standards set by the Directive.

A statistical analysis of the data was carried out and the cost of compliance was estimated at @ £3.5 million for the Health Service and @ £11.2 million for Local Authority Education Services. A further @ £9.5 million investment is required in private sector restaurants and hotels.

The report makes a number of recommendations on future work and data collection.

Table of Contents

Executive Summary

Introduction

Methodology

Parameters
Selection of sample sites
Sample numbers
Questionnaire
Address identification
Sampling

Results

Discussion

Main Findings
Statistical Analysis of Data

Parameters with zero failure rate
Parameters with a number of failures

Costs of complying with the new regulations

Conclusions

Recommendations

Acknowledgements

Introduction

In June 2000, the Water Services Unit (WSU) of the Scottish Executive (SE) Rural Affairs Department commissioned East of Scotland Water (ESW) to carry out a scoping study on water quality compliance in public buildings as required by the new Water Supply (Water Quality) (Scotland) Regulations 2000 which will implement the new Drinking Water Directive 98/83/EC.

This directive sets out new requirements for the quality of drinking water. The new Regulations include these requirements as well as continuing existing standards, which in some cases are more stringent than those stated in the directive. In general, achievement of these standards is the responsibility of the water supply authorities, although they are not held responsible for any effects of pipework within the curtilage of properties.

Article 6 paragraph 2 of the Drinking Water Directive 98/83/EC states:

"In the case of water covered by paragraph 1(a), Member States shall be deemed to have fulfilled their obligations under this Article and under Articles 4 and 8(2) where it can be established that non-compliance with parametric values set in accordance with Article 5 is due to the domestic distribution system or the maintenance thereof except in premises and establishments where water is supplied to the public, such as schools, hospitals and restaurants."

This means that there is an absolute requirement for Member States to comply with regulatory standards where the public are likely to drink. This differs from that in domestic premises, where there is an exemption if non-compliance is shown to be due to the internal plumbing system or supply pipework. These requirements are not included in the new Regulations, but will be included later as amendments after the consultation process is completed.

The overall aims of the study were to identify which types of public building were at risk of non-compliance and to estimate the cost of internal plumbing work to remedy this. It is hoped that the results will also be useful in preparing the Regulation amendments and an appropriate regulatory sampling programme.

Methodology

As quoted above, the Directive gives examples of public buildings as:

schools;
hospitals;
restaurants.

These broad categories were used for the basis of the survey.

Lists of schools and hospitals throughout Scotland were provided by the WSU, lists of restaurants were compiled by ESW's Environment and Quality Regulation team (E&QR) using Address Point (the Post Office address file).

As the purpose of the survey was to assess the quality of water as consumed by members of the public and to identify any internal plumbing problems, it was agreed with the client that the taps should not be flamed or otherwise disinfected prior to taking microbiological samples.

Parameters

Parameters tested were based on check and audit monitoring parameters listed in the Directive and were those considered to be likely to be affected by internal plumbing as well as possible non-compliance of the public water supply fed to the premises. They were as follows:

*For Health & Safety reasons, taste was only done where the water was known to be from a direct mains supply and had a reasonable chlorine residual.

Originally, the WSU included Nitrate in the list of suggested parameters. However, as this was an expensive parameter to test for it was agreed that it would be of more benefit to reduce the parameter list and increase the number of buildings sampled. It was also considered that nitrate was unlikely to be affected by internal plumbing. pH was not originally included, but it was thought that this would be of use to indicate the corrosiveness of the water in relation to metals results. Chlorine residual tests were also carried out in case further assessment was required in the event of a microbiological failure.

It is the policy of ESW Scientific to use procedures that are based on up to date and established standard methods such as the SCA "Blue Book methods; Methods for the Examination of Water and Associated Materials for chemical parameters and Report 71 for Microbiological parameters. All methods are performance tested based on the recommendations in NS30: A Manual on Analytical Quality Control for the Water Industry. Methods are fully documented and under full internal Analytical Quality Control as well being externally assessed by Aquacheck and PHLS proficiency testing schemes. The above policies, which are documented in our Quality Manual and our Quality System, is regularly audited by UKAS.

The North of Scotland Water (NoSWA) Turriff laboratory was used for microbiological samples from the Inverness and Aberdeen areas. These are marked with an asterisk in the qualifier column of the raw results data. The NoSWA laboratory also holds UKAS accreditation for these parameters.

Selection of Sample Sites

It was important to achieve a random spread of sample sites both throughout Scotland and across the range of categories within the public building classifications.

Hospitals were already categorised by type:

• Acute Hospitals (46)
• Care of the Elderly Hospitals (68)
• Cottage Hospitals/Community Hospitals (34)
• Day Hospitals, Health Centres, Community Clinics, GP Surgeries and Clinics owned by NHSiS Holding Bodies (482)
• Hospitals for people with a mental illness (45)
• Other Hospitals (6)

Primary and secondary schools were considered together and categorised by size in the following bands:

• <100 pupils
• 100-249 pupils
• 250-499 pupils
• 500+ pupils

It was thought that the restaurant classification should include hotels, guesthouses, cafés and bars. Many of these places have restaurants or similar places to eat and it was felt to be of importance not to exclude them from the study. They were split into the following categories:

• Hotels/B&Bs/Guest Houses
• Restaurants/Cafés/Pubs

These categories were then split by area to ensure an equal spread throughout mainland Scotland. The areas of the three Water Authorities were used for this purpose. Initially, approximately 4% of each category within each area was calculated. This gave an even distribution and a suitable number of samples for the fixed cost of the survey. However, in the case of hospitals this method gave a very low number of acute hospitals and a high number of Health Centres & GP surgeries. It was thought that members of the public were more likely to consume water, and were more vulnerable to any ill effects of that water, in the former than in the latter. Numbers were adjusted accordingly.

Area lists of each category were printed, for example, schools in the North with less than 100 pupils, arranged alphabetically. The appropriate number was then picked randomly from the lists. Due to the constraints of microbiological sampling, if any of the public buildings picked was located more than four hours drive from the laboratory (for example on islands, remote peninsulas or in the far north) it was disregarded and a replacement picked from the same page.

Sample Numbers

It was decided that larger schools and hospitals should be sampled at a number of points in the building to ensure that more extensive systems were suitably covered. A table of sample numbers is included below:

In each building, one sample was taken from the kitchen tap where available (some schools, for example, had no kitchen). The remaining samples were taken throughout the building, at drinking fountains, wash basin taps, at sinks on wards, wherever seemed appropriate. This decision was left to the samplers to make when on site, as it was obviously impossible to predict the layout of the buildings in advance.

Questionnaire

In order to obtain as much information as possible about the types of buildings that were being sampled, a questionnaire was devised for samplers to complete during each visit. This information assists in attributing, for example, a lead failure to a lead service pipe rather than lead pipes used in internal plumbing. This information would assist in the costing of necessary improvements to ensure compliance.

Address Identification

The address details supplied schools and hospitals were problematic in a number of ways, e.g.:

• No full postal address or grid reference
• No phone numbers
• Spelling mistakes in details provided

Where possible, premises were located before visiting an area in order to reduce the length of time a sampler spent looking for each location. This was done in a number of stages. The full postal address was located, where possible, using the Royal Mail Internet service. Due to security measures at many schools and hospitals, contact had to be made prior to samplers’ visits. The BT Internet service was used to acquire telephone numbers. Maps were supplied to the samplers to assist with the location of buildings on the ground. IT systems from web sites and software such as Microsoft AutoRoute GB 2000 ™ were used to cluster target buildings so as to maximise sampler efficiency once in an area.

Sampling

Samples were collected in purpose-made scientific bottles (manufactured by Aurora Scientific). One 500ml PEP sterile bottle with thiosulphate added for microbiological sampling and two 1-litre PEP general chemical bottles for the other parameters. Samples were carried in cool boxes with ice packs or in refrigerated vans.

Using the pre-identified Public Building addresses, teams of trained East Scotland Water samplers were sent out with detailed instructions, survey forms and letters from the Scottish Executive explaining the purpose of the visit. Where possible prior appointments were made and the customer service centres of the three Scottish water authorities were informed of when and where sampling was taking place. Sampling consisted of taking a random daytime first draw sample from the tap (i.e. without prior flushing) in order to obtain the highest metal levels likely to be consumed. This was followed by the microbiological sample, which was taken without prior flaming of the tap.

The samplers were asked to carry out a taste test on site, but only if they were completely satisfied with the quality of water and associated pipe work. It is not normal to carry out a taste test on a water sample until the microbiological analysis shows a satisfactory result.

Interestingly, three schools in the Glasgow area could not be sampled as the water was turned off whilst the buildings were re-plumbed. If the planned building could not be sampled a nearby one in the same category was chosen.

As a quality assurance check, administrative staff at East of Scotland Water made follow-up telephone calls to a random selection of the buildings sampled. This was in order to ensure that samples had been taken where stated, that the conduct of the samplers was satisfactory and that they had explained the purpose of their visit effectively.

Results

Results are summarised in the Statistical Analysis section below.

Results were treated as confidential and were not fed back to individual premises. The SE informed the appropriate Water Authority regarding microbiological failures, stressing that the tap had not been flamed.

The random telephone QA checks highlighted no problems and those spoken to were happy with the samplers’ conduct and explanations.

Discussion

Main Findings

The parameter found to exceed the PCV most frequently was lead at above 10μg/l. The majority of lead failures were in Primary Schools (14 samples from 10 schools) and in Hotels etc. (15 samples from 12 establishments). A variety of different taps failed, including kitchen taps. Only three of these buildings, two primary schools and a guesthouse, had a lead mains pipe entering the building.

There was one failure in each of Copper, E.coli and F.Streps, at a Health Centre, Hotel and Primary School respectively.

Statistical analysis of data

In order to assess the likely level of compliance in public buildings across Scotland with the standards set in the new drinking water directive, the data were examined in order to derive statistically the true level of compliance in all buildings throughout the country.

There are approximately 7900 public buildings in Scotland, which fall into the three categories. The number in each category is summarised in Table 1.

Table 1 Number of public buildings in Scotland

Although the sampling category Hotels and Restaurants was split in two (Residential and non-residential), there are no figures for the total number in each category. Therefore it was assumed that the sampling split (57% non-residential and 43% residential) was representative of the situation as a whole. Hence, of the 4537 buildings, which form the combined category, it was assumed that 2596 were non-residential and 1941 were residential.

The number of samples taken from each category, together with the number of failures for each parameter, are shown in Table 2.

Table 2 Outcome of sampling programme

At the beginning of the survey it was decided to review data and modify the sampling programme accordingly. For example, if a large number of failures are found in a small population this indicates at an early stage that there is low compliance and it is therefore unproductive to continue sampling that category. Alternatively, if compliance is high than a lot more samples are required to establish statistically that this is in fact the case. From the table above it can be seen that the level of compliance within the sample population is generally fairly good. It was therefore decided to continue throughout with the original programme.

Parameters with zero failure rate

Although certain parameters have a zero failure rate, this does not mean that the true underlying failure rate is also zero, although this is obviously possible. It does, however, allow us to predict a 90% confidence interval for the actual failure rate. For a Type II risk of 5%, the true compliance rate for each category for these parameters is given in Table 3 below.

Table 3 Estimates for Parameters with Zero Failure Rate

Note that the prediction of the failure rate is obviously dependent on the number of samples taken. The greater the number of samples taken then the more confidence there is that the population as a whole is compliant. Hence, hospitals are seen as having a higher failure rate, but only 32 premises were sampled, in comparison with over 100 restaurants. Note also that the success/failure rate is the same for each parameter within a sampling category. For example, from the above results between zero and 61 hospitals are likely to fail to comply with copper, turbidity, F.Streps and E.coli standards. However, whether these failures all occur within the same hospitals cannot be determined.

Parameters with a number of failures

Of the six parameters sampled, four have exhibited one or more failures, with the lead standard being the one most frequently failed. Here it is not so straightforward to assess the likely level of true compliance. The question is, given that we know the sample exceedance rate (e.g. 30 buildings, from a total population of 303, failed to comply with the lead PCV), what might the population exceedance rate look like. This implies that we need to construct a confidence interval for the population exceedance rate. Confidence intervals were determined non-parametrically and are shown, together with the corresponding number of failing buildings in the following table.

Table 4 Confidence Intervals for Failing Parameters.

Finally, a breakdown is given of the likely number of buildings, which will fail to comply with the revised Directive, specified by category and parameter.

Table 5 Estimated number of failing buildings by category and parameter

Note that no account has been taken in this analysis of the geographical spread of the sample population. It was felt that there was no benefit to be had by splitting the results by water authority area, this process was used simply to ensure that the majority of mainland Scotland was covered by the survey.

Statistical analysis suggests that between 18 and 153 buildings in the hospital classification could fail to comply with the Drinking Water Regulations for at least one of the parameters tested. The "best estimate" from within this range is 64. A best estimate for any parameter failing in each of the categories is identified in the final column of Table 5 and this is used in the cost estimates.

Considering that the taps were not flamed prior to sampling, the number of microbiological failures was surprisingly low. This calls into question the necessity of flaming taps when undertaking statutory sampling.

It was noted that many of the larger hospitals had provision for secondary chlorination in the stored water system. This is likely to have contributed to the low number of microbiological failures despite the need for header tanks and is a practice to be commended.

Costs of complying with the new Regulations

Where failures of new regulatory standards have occurred as a result of the internal plumbing installation the owners of the public building will be required to carry out the necessary works. This is not the case in respect of private/domestic buildings. It is not yet clear how this will be enforced by the Regulations. For example, will all buildings be required to be tested and certificated? Will there be enforcement procedures as a result of non-compliance of a random sample? Should there be a survey carried out on the condition of plumbing in all of these buildings?

For full compliance and to audit this a combination of all 3 will probably be required, this would take a number of years and work would need to be done in a phased manner to spread the costs.

The survey carried out indicates that plumbing is generally satisfactory in the buildings looked at and that the main non-complying parameter is lead. Lead is not present in any significant levels in water supplies in Scotland and its presence indicates a plumbing problem. The survey indicated that as buildings had been extended and modernised over the years the plumbing had also been upgraded. Of all the sites where lead samples did not comply only three had any visible lead pipework and of all sites inspected we only found exposed lead pipe at seven sites.

The lead failure may be due to:

• the water authority owned communication pipe
• the supply pipe
• lead solder
• hidden internal lead piping

If the water authority owned communication pipe is the problem there is a responsibility on the water authority to replace it once all internal lead pipework has been removed, or once the Regulations are in place, after any sample taken has exceeded the PCV. The cost of replacement of lead communication pipes will be borne by water authorities and allowance for this is included in their investment plans.

The cost of a new supply pipe depends primarily on its length and the work required to lay it (i.e. whether it crosses hard areas or goes under buildings etc), rather than its diameter. Typically the cost of supply pipe replacement will be (based on an estimate of @ £20 per metre plus connection costs of @ £250):

• School 2-3K
• Hospital @ £2-5K
• Health Centre/Surgery @ £1K
• Hotel or Guest House @ £1-2K.

The Directive applies a phased standard for lead, i.e. 25μg/l from end of 2003 to 10μg/l from end of 2013. The former standard may be achieved by water authority measures to reduce the plumbosolvency of the water supply e.g. pH control and/or orthophosphate dosing but the latter standard is only likely to be met by removing all lead in the system.

Although the survey only identified three non-compliant sites with lead pipework the failures may be due to the presence of lead solder in the joints. Prior to 1989 lead solder could be used legally and since then we have found evidence of its use in contravention of water byelaws. This can only be accurately assessed by the use of test papers and detailed examination of supply and communication pipes. There may be a need for complete replumbing of the cold water system if this is the case.

Overall, the statistics and data from the survey indicate a generally high level of compliance but statistically there is the likelihood that there will be buildings that do not comply with any of the parameters tested.

We were required, therefore, to make an assessment of the cost of replumbing the cold water systems in a range of public buildings to meet the Regulations for points where the public may drink.

To this end our engineer visited four sites and carried out a detailed costing survey of replumbing that may be required. The estimates were then used to calculate total costs in the sectors under study. The estimates were also compared to recent work carried out on such buildings by registered plumbing contractors. (One of these contractors remarked that in his experience there were many public buildings with poor condition copper pipe which was pitted and tended to leak, although this was not reflected in copper analysis.)

The estimates were as follows:

Plumbers range @ £6-50K (depending on size, very large hotels could be considerable more.)

Therefore, a best estimate (weighted average) of the cost of upgrading a building in each category is:

Using the ‘best case’ statistical information from the sampling, which is calculated using the lowest estimated number for any failing parameter in a sector, best estimate cost figures give an estimated total compliance cost in each sector as follows:

Using the ‘worst case’ statistical information from the sampling, which is calculated using the highest estimated number for any failing parameter and the best estimate cost figures gives an estimated total compliance cost in each sector as follows:

Using the ‘best estimate’ figure for any failing parameters, best estimate cost figures give an estimated total compliance cost in each sector as follows:

Conclusions

The compliance as measured by the sampling programme was better than expected but the limitation in the number of sites and samples taken means that statistically there is still a chance of a significant number failing on one or more parameters.

Using the best case estimates the assessed cost to the public purse is estimated at @ £3.5million for the Health Service and @ £11.2million for Local Authority Education Service.

It is estimated that a further cost of @ £9.5million will have to be borne by the private sector for restaurants and hotels etc.

The sampling indicated that lead was the most commonly failing parameter and the one that required attention. It has not been established if this results from use of lead solder or lead pipework. A similar situation exists in the domestic sector.

The survey indicated that the standard of internal plumbing was generally good and that as development over the years had occurred plumbing had been upgraded.

It was reassuring that hospitals were maintaining chlorine residuals in their cold water systems.

Recommendations

There are many buildings used by the public that were not covered by this scoping study. For example, universities and colleges, sports centres, libraries, public halls, dental surgeries and public toilets, all of which offer tap water to members of the public. We recommend that subsequent research be commissioned to cover such buildings.

We recommend that the research be expanded to include areas further afield, including the islands, where lower regional economic investment may have resulted in fewer modernised internal distribution systems.

We recommend a separate sampling regime for public buildings under an amendment to the new Drinking Water Regulations and that the data obtained is used in association with this report to improve the statistical robustness of our assumptions.

We recommend that drinking water taps are clearly labelled as such. This will also help in the correct sampling of buildings under the new Regulations.

We recommend that all public buildings be required to establish if they are served by lead service pipes and that if so they are replaced as soon as possible. If lead failures still occur the presence of lead soldered joints should be assessed.

We recommend detailed guidance for owners of public buildings to establish their duties in respect of the new Amended Drinking Water Regulations and in inspection and upgrading of their plumbing systems.

Acknowledgements

We are particularly grateful to East of Scotland Water’s sampling team and the analysts at ESW Scientific for all their efforts.

We also thank the Regulation team of the Water Services Unit for their help and assistance.

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