Advances in Water Treatment and Enviromental Management

WATER SUPPLY QUALITY IN PRIVATISED UK WATER SERVICES 35to this are for total coliforms and sodium. For total coliforms the water complies if 95 % of thesamples in any period meet the standard. The period will normally be one year, but if less thanfifty samples have been taken from a zone in one year the results of the previous fifty samplesare taken regardless of the period. For sodium, 80% of samples taken in the past three yearsmust not exceed the standard for the water to comply.For the parameters in Table I compliance is based on the average of results of analyses overtwelve months are compared with the standards. (For trihalo methanes a rolling three monthperiod is used.) For samples of water leaving treatment works and in service reservoirs, everysample must comply with the bacteriological parameters for the water to be wholesome.5.2 Relaxations of the Standards.Subject to there being no risk to public health, the Secretary of State may relax the standardsfor geographically defined areas where supplies fail to comply for specified reasons, as permittedby the EC Directive (Article 9). Where supplies are affected due to emergencies or exceptionalweather, temporary relaxations can be granted; temporary or permanent relaxations can beapproved due to the nature or structure of the ground. Conditions may be imposed to requireimprovements to water quality or monitoring.5.3 Section 20 Undertakings Given to the Secretary of State.The Secretary of State has a duty under the Water Act to enforce the standards of wholesomewater. However, Section 20 of the Act allows him discretion in enforcement where a) thecontraventions are trivial or b) he is satisfied that the water supplier has given, and is complyingwith, an undertaking to take all necessary steps to achieve compliance (a “Section 20Undertaking”). These are the type of action programmes referred to in Article 20 of the ECDrinking Water Directive. The Secretary of State can still enforce compliance against a companydespite an Undertaking, if there are grounds for doing so.6 REVIEW OF CURRENT QUALITY6.1 Level of compliance.In November 1989 each water holding company summarised its water quality in detailedprospectuses (Schroder, 1989) which were independently vetted by auditors as part of thewater privatisation share offer. A general view of the current water quality and the difficultiesfaced can be drawn from this source. The companies have tried to assess retrospectively thecompliance of their supplies in 1988/9 with the quality standards in the Regulations. Insome cases the location and manner of sampling was dissimilar from the Regulations’requirements, but the extent of sampling was considerable. Thames Water, for examplereported 471,000 tests for 53 of the 57 parameters in the Regulations with only 627 failures(0.13%) overall. Wessex Water estimated 99,000 tests on 9,700 samples from distributionsystems and only 289 failures, (a compliance rate of 99.7%).Reported compliance for tap samples ranged from 88–94% for aluminium, iron, manganeseand trihalomethane in Yorkshire, 95.5% for iron in North West and overall, for a wide rangeof parameters, from 98.2 to 99.8% for other companies. The Regulations require 100 %compliance for most parameters and notwithstanding these high compliance figures, it wasacknowledged by the Government that this could not be achieved instantaneously. Hence itpermitted Relaxations and Section 20 Undertakings, relating them to water sampling zones,although the remedial action could refer to specific water treatment works or service reservoirsas appropriate. Water supply quality deficiencies which affected only part of the zone stillrequired the whole zone to be nominated.7 RELAXATIONSRelaxations covering an estimated 3% of the population of England and Wales were grantedin November 1989 for sodium, dissolved hydrocarbons, sulphate, magnesium, potassium,colour, aluminium and manganese. These are subject to review at the end of 1994 or earlier,when they might be renewed. Temporary relaxations have been granted, subject to agreedimprovement programmes designed to achieve compliance by given dates up to 1995, forcolour, turbidity, pH, odour, taste, oxidisability, nitrite, ammonium, aluminium, iron andmanganese. The parameters covered by relaxations affecting the Water Services companiesare given in Table III.