Drinking Water 2003

The EC Directive on the quality of water intended for human consumption came into force on 25 December 1998. This sets out new and revised standards for a number of parameters, which have been incorporated into the Water Supply (Water Quality) Regulations 2000 and the Water Supply (Water Quality) Regulations 2001 (the new Regulations). The 2000 Regulations apply to water companies whose area of supply is wholly or mainly in England and the 2001 Regulations apply to water companies whose area of supply is wholly or mainly in Wales. The majority of the new Regulations came into force on 25 December 2003. However some parts of the new Regulations, which are not directly related to the Directive, came into force in England on 1 January 2001, and in Wales on 1 January 2002.

The new Regulations require water companies to monitor against new standards for six parameters. These parameters are listed in Table 1 below.

Table 1

Water companies are also required to monitor against tighter standards for nine parameters and a more relaxed standard for one parameter, which were included in the Water Supply (Water Quality) Regulations 1989 (1989 Regulations). These are listed in Table 2 below. The standards under the 1989 Regulations remained in force until 25 December 2003.

Table 2

The new standard for Polycyclic aromatic hydrocarbons (PAHs) relates to the sum of four substances, rather than the sum of six substances, as specified in the 1989 Regulations.

The new Regulations also introduce tighter standards for Trihalomethanes (THMs), with an absolute maximum concentration of 100 µg/l instead of a threemonthly rolling mean, and for benzo3,4pyrene, with an absolute concentration of 0.010 µg/l instead of an annual average. A formula has also been introduced for nitrate and nitrite of [nitrate]/50 + [nitrite]/3 being less than or equal to one, where the square brackets signify the concentration in mg/l for nitrate as NO ₃ and nitrite as NO₂.

Programmes of work

Regulation 41 of the new Regulations required water companies to submit for approval programmes of work to meet the requirements of the new and revised standards which came into force on 25 December 2003. These programmes of work have been approved by the Inspectorate and have been implemented by the water companies.

The Inspectorate has monitored progress with the implementation of the programmes, and conducted audits of individual schemes. Adjustments have been made to actions and completion dates, as necessary. Overall progress has been satisfactory and most programmes were complete by 25 December 2003. The few schemes that were not complete do not affect water quality because, for example, the relevant treatment works is not in supply or sufficient improvement to treatment has already been made i.e. in the case of the interim standard for lead.

Authorised departures

Under the new Regulations water companies may apply to the Secretary of State or the National Assembly for Wales (the Authorities) for authorisation to supply water that is not wholesome, if they have reason to believe that the water is failing or is likely to fail a prescribed standard. A condition of each authorisation is that the companies must take steps to improve the supply by specific dates. Such remedial work should be completed within a threeyear period, although a further authorisation may be granted. However an authorisation can only be granted if the Authorities are satisfied that it does not constitute a potential danger to human health.

Regulation 42 of the 2000 Regulations permitted water companies to apply for authorisations where they had reason to believe the water would not satisfy the requirements of the new Regulations. Eight completed applications were received by the due date and all were granted authorisations. Details of the authorisations have been published locally and are available on the Inspectorate’s website.

Results of monitoring in 2003

The Inspectorate first requested water companies in England and Wales to submit a summary of results of samples taken for the six new parametric values (benzene, bromate, 1,2 dichloroethane, nitrite exwater treatment works, Clostridium perfringens and Enterococci) in 2001. The purpose of this exercise was to allow companies to identify where further improvement programmes might be necessary to meet the Directive requirements by the due date. A comparison of the results is shown in Table 3.

It should be noted that, because sampling was not necessarily undertaken at the monitoring frequency specified in the Directive, the results cannot be interpreted at this stage in terms of percentage ‘compliance’. As of 1 January 2004, monitoring for the new parameters will be at the frequencies specified in the new Regulations.

The overall number of samples failing to meet the new standards is small and very few contraventions are anticipated during 2004. For example remedial action has already been taken, or is being taken, in respect of most of the bromate failures. However, further improvement programmes will be put in place should any nontrivial failures occur in 2004.

Table 3 – The six new parameters

Compliance data for 2003 taken under the 1989 Regulations have also been analysed to show ‘compliance’ against the revised parametric values in Directive 98/83/EC.

For lead, copper, nickel and PAH, exact comparisons are possible because all data are for consumers’ taps. For the other parameters, some samples have been taken at supply points so ‘compliance’ can only be estimated.

Table 4 – Revised parameter values

The monitoring confirms that in 2004 compliance with the new standard for lead will be an issue for some water companies. However, a ‘noncompliance’ figure of 0.74 per cent demonstrates that the plumbosolvency control measures already in place are having a significant impact on meeting the standard of 25µg/l. Previous ‘non–compliance’ figures for lead measured against the 25µg/l standard were 2.01 per cent in 2001 and 1.32 per cent in 2002. The Inspectorate has already taken steps to ensure that water companies have lead strategies in place to address any failures that occur.

Most of the ‘contraventions’ of the new standard for arsenic were in areas supplied by one company. The company completed a number of improvement programmes for arsenic during 2003.

Likewise most of the ‘contraventions’ of the new combined standard for tetrachloroethene and trichloroethene related to areas supplied by one company. The company will be required to take appropriate remedial action if these continue into 2004.

With the exception of lead and the schemes where authorised departures have been granted, few contraventions of the revised standards are anticipated in 2004. However, further improvement programmes will be put in place should any nontrivial failures occur in 2004.