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Drinking Water Quality in Scotland 2002
2. Introduction
Role of the Regulator
Section 7 of the Water Industry (Scotland) Act 2002 created the post of Drinking Water Quality Regulator for Scotland (DWQR). This placed the functions of the Regulator on a statutory footing. Although the DWQR has similar functions to those of the Drinking Water Inspectorate (DWI) in England and Wales, the separation between Ministers and the Regulator is greater in Scotland than England and Wales because Scottish Water is a publicly owned body. This contrasts with the position in England and Wales where the water utilities are privately owned companies. In Scotland the DWQR is responsible for enforcing The Water Supply (Water Quality) (Scotland) Regulations independently of Ministers, whereas the DWI carries out this role on behalf of Ministers.
Powers of the Regulator
The DWQR has three main powers. These are in respect of the power to obtain information, the power of entry or inspection and the power of enforcement.
In addition, the DWQR has emergency powers to require a water supplier to carry out works to ensure that the quality of water supplied is safe for public consumption. The DWQR can also vary and/or withdraw notices but he must keep a register of any notices issued. Finally, the DWQR can instruct a local authority to provide information held by it with regard to enforcement undertaken by the local authority.
Activities of the Regulator
At the end of each calendar year the Regulator must submit an annual report to Scottish Ministers. The annual report summarises and comments on the drinking water quality results for the preceding year. It also includes an account of any investigations or enforcement actions carried out by the Regulator during the period covered by the report.
This is the first annual report that has been prepared by the Drinking Water Quality Regulator for Scotland (DWQR) and submitted to Scottish Ministers. It presents and reviews the information provided by Scottish Water under the Water Supply (Water Quality) (Scotland) Regulations 1990 and reflects the dealings that the DWQR had with Scottish Water between 1 January and 31 December 2002.
This report presents a detailed assessment of drinking water quality in Scotland during 2002 in terms of the standards set in the 1990 Regulations. Where appropriate the report also Make comparisons of the performance in 2002 with that in earlier years.
Throughout the report reference is made to the need for action where non-trivial breaches of the standards set in the 1990 Regulations have been identified. If Scottish Water is not able to take action quickly to remedy such a breach then Scottish Water will normally give a legally binding undertaking to Scottish Ministers to take steps to secure compliance. If Scottish Ministers do not receive an appropriate undertaking, enforcement action can be taken.
The 10 Key Drinking Water Quality Standards in Scotland are:
Parameter | Significance |
Total Coliforms | The coliform group of organisms is present in large numbers in the gut of all warm-blooded animals but are also widely distributed in the environment. While their presence in water supplies indicates a breach in the integrity of the water supply system, it may not be presumed that faecal pollution has occurred. |
Faecal Coliforms | Faecal coliforms are present in large numbers in the gut of all warm-blooded animals. Their presence in water supplies indicates a breach in the integrity of the water supply system and that faecal pollution may have occurred. |
Colour | Colour is derived from humic substances which occur naturally, particularly in acidic water sources derived from moorland catchment areas. High colour may be unacceptable to consumers on aesthetic grounds and the humic substances responsible for colour are precursors of disinfection by-products. Colour may be removed by coagulation/sedimentation/filtration. |
Turbidity | Natural turbidity is caused by suspension of finely divided or colloidal matter of predominantly inorganic origin. Turbidity may also be caused by the breakthrough of coagulant floc from overloaded or badly maintained filters. High turbidity is unacceptable to consumers on aesthetic grounds and may also compromise disinfection. Turbidity levels are controlled by effective operation of treatment processes. |
Hydrogen Ion (pH) | Most surface waters and many groundwaters are slightly corrosive towards the materials used in water treatment systems and consumers installations. This effect persists even when the pH exceeds the neutral point (pH7) and is countered by adding an alkali during treatment to raise the pH. As chlorine disinfection is more effective at low pH addition of Alkali is normally made after the disinfection stage. Extreme pH values may present a risk to the health of consumers. |
Aluminium | Aluminium occurs in acidic waters derived from moorland catchments and is removed in water treatment by coagulation and filtration. High concentrations are unacceptable to consumers on aesthetic grounds. Aluminium sulphate is used as a coagulant in water treatment. Claims of a weak association between low concentrations of aluminium in water supplies and the incidence of Alzheimer's disease have not been substantiated. |
Iron | Iron is present naturally in many water sources and is removed by conventional water treatment processes. Iron in water supplies may also be derived from corrosion of iron mains and inadequate filtration of the residues of iron based coagulants used in water treatment. High iron concentrations are unacceptable to consumers on aesthetic grounds. |
Manganese | Manganese occurs naturally in many water sources and particularly high concentrations are encountered in anaerobic groundwaters. Conventional water treatment processes remove manganese. Elevated manganese concentrations are unacceptable to consumers on aesthetic grounds. |
Lead | Lead is not normally present in water sources but significant concentrations may be present at consumers' taps if lead pipes are present and the water supply is plumbo-solvent. |
Trihalomethanes | Trihalomethanes occur in drinking water principally as products of the reaction of chlorine with naturally occurring organic materials and with bromide, which may also be present in the water. In controlling trihalomethanes, a multi-step treatment system should be used to reduce organic trihalomethane precursors, and primary consideration should be given to ensuring that disinfection is never compromised. |
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