Dwr Cymru Cyfyngedig
Introduction
Dwr Cymru Cyfyngedig supplies on average about 1000 Ml/d of water to about 2.8 million consumers in an area covering most of Wales and parts of Hereford and Worcester. and Gloucestershire. Approximately 59% of the Company's water supplies come from impounding reservoirs, 35% from river abstractions and 6% from boreholes and springs. The Company has 111 treatment works on 111 sites, and distributes water through 24,900 km of pipes and 572 service reservoirs to 184 water supply zones. In addition there is a small bulk supply from Severn Trent Water Limited.
Overall water quality
At water treatment works and service reservoirs and in water supply zones, the Company carried out a total of 180,729 determinations in 1999. Of these, 99.8% demonstrated compliance with the relevant PCV, but 423 showed a contravention to have occurred.
Coliforms were not detected at 103 (93%) of the Company's 111 water treatment works. At 571 (>99%) of the Company's 572 service reservoirs, coliforms were absent from at least 95% of samples. Of the Company's 184 water supply zones in 1999, 178 (97%) complied fully with the relevant water quality standards or had breaches of the standards which were either trivial or were fully covered by undertakings. In the other 6 (3%) of the zones, some breaches have resulted in consideration of enforcement action.
Microbiological quality of water leaving treatment works
The Company complied with the sampling frequencies required by regulation 17 at all its treatment works in 1999.
Table 7.1 shows the Company's performance in 1999, with data for 1998 and 1997 for comparison. There have been significant decreases over the three years in the number of treatment works, and samples from treatment works, in which coliforms or faecal coliforms were detected. Other differences between the three years are not considered significant.
Table 7.1 Dwr Cymru Cyfyngedig
MICROBIOLOGICAL QUALITY OF WATER LEAVING TREATMENT WORKS1999 1998 1997 Number of water treatment works 111 111 119 Works with no sampling shortfall 111 111 116 COLIFORMS Total number of determinations 14,647 15,319 16,089 - number containing coliforms 10 22 60 - % containing coliforms 0.1 0.1 0.4 Treatment works with coliforms detected 8 18 36 - % of all works 7 16 30 FAECAL COLIFORMS Total number of determinations 14,647 15,319 16,088 number containing faecal coliforms 0 5 16 - % containing faecal coliforms 0.0 <0.1 0.1 Treatment works with faecal coliforms detected 0 5 13 - % of all works 0 5 11 Contraventions of the microbiological quality standards at one works have resulted in the consideration of enforcement action, as shown in table 7.4. All other contraventions of the standards at works are considered trivial.
Microbiological quality of water in service reservoirs
The Company complied with the sampling frequencies required by regulation 18 at all of its service reservoirs in 1999.
Table 7.2 shows the Company's performance in 1999, with data for 1998 and 1997 for comparison. There have been significant decreases over the three years in the number of service reservoirs, and samples from service reservoirs, in which coliforms or faecal coliforms were detected. Other differences between the three years are not considered significant.
Contraventions of the microbiological quality standards at two service reservoirs have resulted in the consideration of enforcement action, as shown in table 7.4. All other contraventions of the standards at service reservoirs are considered trivial.
Table 7.2 Dwr Cymru Cyfyngedig
MICROBIOLOGICAL QUALITY OF WATER IN SERVICE RESERVOIRS1999 1998 1997 Number of service reservoirs 572 597 611 Service reservoirs with no sampling shortfall 572 595 608 COLIFORMS Total number of determinations 30,461 30,915 31,939 - number containing coliforms 59 74 161 - % containing coliforms 0.2 0.2 0.5 Service reservoirs with coliforms detected 53 64 132 Service reservoirs with coliforms detected in
more than 5% of samples1 2 6 - % of all service reservoirs 0.2 0.3 1 FAECAL COLIFORMS Total number of determinations 30,461 30,916 31,941 - number containing faecal coliforms 17 18 39 - % containing faecal coliforms 0.1 0.1 0.1 Service reservoirs with faecal coliforms detected 15 16 37 - % of all service reservoirs 3 3 6 Water quality in water supply zones
The Company complied with the required sampling frequencies for all parameters in all zones.
Table 7.3 shows the Company's performance in 1999, with data for 1998 and 1997 for comparison. There has been a significant decrease over the three years in the number of zones contravening the standard for faecal coliforms, and a significant increase for trihalomethanes. All other differences between the three years are not considered significant.
Enforcement action is being considered in respect of some contraventions of standards, as shown in tables 7.3 and 7.4. All other contraventions of the standards in zones are considered trivial or are covered by undertakings.
Table 7.3 Dwr Cymru Cyfyngedig
WATER QUALITY IN SUPPLY ZONESColumns 'CBU' show, for determinations, contraventions covered by undertakings and, for zones, the total number of zones covered by undertakings in 1999. Column 'E' shows the number of zones for which new enforcement action is under consideration as a result of contraventions of the PCV in 1999. Please refer to the Introduction to Part 2 for more detailed explanation of this table. PARAMETER DETERMINATIONS in 1999 ZONES (184 in 1999)* Total Contravening PCV Non-compliant No. % CBU CBU E Number in: 1999 1999 1998 1997 Coliforms 9,432 33 0.4 0 0 0 0 1 3 Faecal coliforms 9,433 2 <0.1 0 0 0 2 4 15 Colour 988 0 0.0 0 1 0 0 0 0 Turbidity 1,090 1 0.1 1 179 0 1 2 1 Odour 1,387 3 0.2 0 0 0 3 4 6 Taste 1,381 1 0.1 0 0 0 1 6 5 Hydrogen ion 1,182 5 0.4 3 3 1 3 2 1 Nitrate 910 0 0.0 0 0 0 0 0 0 Nitrite 1,954 123 6.3 91 26 0 30 28 27 Aluminium 1,154 3 0.3 0 43 0 3 4 5 Iron 2,660 62 2.3 60 187 0 37 49 60 Manganese 1,515 9 0.6 7 62 0 8 15 11 Lead 516 3 0.6 0 1 0 3 8 11 PAH 1,019 67 6.6 51 72 0 33 34 38 Trihalomethanes 779 12 1.5 3 3 5 6 4 1 Total pesticides 1,162 2 0.2 0 0 0 2 1 2 Asulam 793 0 0.0 0 0 0 0 1 0 Atrazine 751 2 0.3 0 0 0 2 1 0 2,4-D 628 1 0.2 0 0 0 1 2 1 2,4-DB 627 0 0.0 0 0 0 0 1 1 Carbendazim 559 1 0.2 0 0 0 1 0 0 Linuron 746 1 0.1 0 0 0 1 0 0 MCPA 631 1 0.2 0 0 0 1 1 1 MCPB 621 0 0.0 0 0 0 0 0 1 Mecoprop 623 1 0.2 0 0 0 1 2 2 Mancozeb 568 1 0.2 0 1 0 1 0 3 rietazine 748 0 0.0 0 0 0 0 0 1 Other pesticides 23,766 0 0.0 0 0 0 0 0 0 Antimony 203 0 0.0 0 0 0 0 0 3 Benzo-3,4-pyrene 1,019 2 0.2 0 0 0 0 0 0 Oxidizability 192 1 0.5 0 0 0 1 0 1 Temperature 9,314 0 0.0 0 0 0 0 0 1 Zinc 213 0 0.0 0 0 0 0 0 1 All others 11,949 0 0.0 0 0 0 0 0 0 TOTAL 90,513 337 0.4 216 - - - - - *189 zones in 1998; 200 zones in 1997.
Inspection
Mr A Hallas, Inspector, carried out an inspection of the Company during September 1999.
He concluded that:
Improvement programmes
- the Company has made appropriate and positive response to the recommendations and consideration of enforcement made in 1998 report;
- based on the audit trails of selected compliance results, the Company continued to have general arrangements for sampling which satisfy Parts IV and V of the Regulations and satisfactory and secure arrangements for reporting compliance information; and
- several deficiencies were identified relating to sampling and performance of the analytical methods.
Between September and November 1999, Consultants Binnie, Black and Veatch, working under the direction of Mr W M Waite, Principal Inspector, carried out an audit of the Company's procedures for operation and management of the distribution system. Based on their report Mr Waite concluded that:
- the Company has procedures which cover most aspects of the operation and maintenance of their distribution network. These procedures are generally clear. However, some of the procedures lack detail on how the operations should be implemented and the criteria by which decisions should be made. In particular procedures could give further guidance with respect to minimising the potential for discolouration of supplies. However, the Company does not have any procedures which address the content of two of the 10 checklists used by the consultants.
Mr R M Walls, Consultant, working under the direction of Mr W M Waite, Principal Inspector, carried out audits of the Company's responses to the recommendations made by the Group of Experts on Cryptosporidium in Water Supplies in their Third Report (the Bouchier Report) and the incorporation of the Technical Guidance Notes on Water Supply Hygiene into the Company's procedures. Based on his report Mr Waite concluded that:
- the Company had generally responded or is responding to the recommendations made in the Bouchier report. A few areas were identified where the Company's response could be improved. The Company generally has procedures which incorporate the Technical Guidance Notes, but certain practices need to be set down in procedures.
In October 1999, Parkman Consultants, represented by Mr B Jones, working under the direction of Mr P Halton, Inspector, carried out an audit of the Company's progress with the programme of mains renovation set out in the distribution system Undertaking submitted by the Company. Based on Mr Jones' report, Mr Halton's main conclusions were that:
- the objectives of the Undertaking remained valid;
- the steps to be taken were defined with adequate precision;
- a practicable timetable had been set; and
- the Company was likely to meet the target renovation length by the date for completion of the work.
As a result of these inspections, 19 recommendations were conveyed to the Company for formal response, two thirds of the recommendations resulted from review of procedures for operation and management of the distribution network. Nineteen suggestions on various matters were also made. The Company is taking action or has already taken action on a number of the recommendations.
Eight undertakings in respect of improvement programmes were due for full completion or the completion of major steps during 1999 and all of these were completed on schedule.
Incidents
Nine of the events notified during 1999 by the Company to the Secretary of State under the terms of the Water Undertakers (Information) Direction 1998 are regarded by the Inspectorate as constituting incidents in which drinking water quality demonstrably deteriorated.
Of the nine incidents, seven involved the supply of discoloured water, one involved the detection of taste and odour in supply and one was a disinfection failure. Two of the incidents remain under consideration by the Inspectorate.
In February 1999, discoloured water was supplied to the areas of Pembroke and Manorbier, Pembrokshire and to parts of Rhyl, Pensarn and Kinmel Bay in Denbighshire because of burst mains. In July and October 1999, discoloured water was supplied to parts of Milford Haven, Pembrokshire, on the first occasion because of increased demand on the system due to dry weather, and on the second as a result of a burst main. In July 1999 discoloured water was supplied on two occasions to parts of St Asaph, Denbighshire. The first time was caused by a blockage in a newly installed pressure control valve complex (PRV) that disturbed mains deposits in the distribution system. The PRV has since been fitted with an alarm system. The second was a result of high demand on the system which disturbed mains sediment. In November 1999, discoloured water was supplied to areas of Ebbw Vale due to several bursts on a main within two days.
In June 1999, undisinfected water was supplied to four villages in Herefordshire due to a mechanical failure of the chlorine motive water pump at Leintwardine treatment works. A precautionary advice to boil water was issued to consumers. All bacteriological samples taken in distribution were satisfactory.
Between the 2 August and 15 September 1999, there was an earthy taste to the water supply from Bryngwyn Water Treatment Works caused by a naturally occurring metabolite from algae. Enhanced treatment through the addition of Powdered Activated Carbon commenced at the works on 19 August to reduce the level of metabolite entering the water supply. This treatment achieved a reduction in the number of consumer complaints received by the Company of poor tasting water.
No other events regarded as constituting incidents came to the attention of the Inspectorate in 1999.
Enforcement action
Table 7.4 summarises enforcement action under consideration or taken for the Company as a result of the Inspectorate's work in, or pertaining to, the calendar year 1999.
Table 7.4 Dwr Cymru Cyfyngedig
SUMMARY OF ENFORCEMENT ACTION CONSIDERED IN 1999Regulation Reason for enforcement 3(3)(c) Contravention of the standard for hydrogen ion in one zone. 3(3)(e) Contravention of the standard for trihalomethanes in five zones. 3(7) Contravention of the coliform standard at one treatment works. 3(7) Contravention of the coliform standard at one service reservoir and the coliforms and faecal coliform standards at one service reservoir.
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Drinking Water Inspectorate,
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Published 12 July 2000; Updated 11 July 2001
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