6 Dee Valley Water Plc
Overall Water Quality supplied by Dee Valley Water Plc in 2001
- A total of 13,033 tests were carried out by Dee Valley Water Plc in 2001.
- Of these tests, 99.88% complied with the Regulations.
Company Information
Amount of Water Supplied: 73 Ml/d
Consumers Supplied: 257,100
Areas of Supply: Chester, Wrexham, Llangollen and surrounding areas of Denbighshire and Flintshire
Water Composition: 96% from rivers and reservoirs
4% from boreholes and aquifers
Treatment Works: 7
Service Reservoirs: 30
Km of Mains: 1,953
Water Supply Zones: 18Overall Water Quality supplied by Dee Valley Water Plc in 2001
A total of 13,033 tests were carried out by Dee Valley Water Plc in 2001.
Of these tests, 99.88% complied with the Regulations.Water Quality in Water Supply Zones, at Treatment Works, and in Service Reservoirs
Water supply zones
- To be wholesome, water must comply with the standards set out in the Regulations. The Company carried out a total of 7,191 tests on samples taken in its 18 water supply zones. The table below includes only the parameters that breached the standard; all other parameters were fully compliant. A list of these parameters and their significance can be found at the beginning of this section.
- The last column indicates the number of failures in zones already covered by legally binding undertakings given by the Company. These undertakings required remedial work to be carried out to ensure compliance with an individual standard.
Parameter Total samples taken Samples not meeting the standard Percentage Number of failures already covered by undertakings Nitrite 201 8 3.98 0 Iron 239 1 0.42 0 Manganese 172 3 1.74 2 Treatment works
- There were no contraventions of the microbiological standards at any of the Company's treatment works in 2001. Differences over the last three years in the number of treatment works, and samples from treatment works, in which coliforms or faecal coliforms were detected were not considered significant.
Service reservoirs
- At all of the Company's 30 service reservoirs, coliforms were absent from at least 95% of samples. A single failure of the faecal coliform standard at one service reservoir was considered trivial or unlikely to recur. Differences over the last three years in the number of service reservoirs, and samples from service reservoirs, in which coliforms or faecal coliforms were detected were not considered significant
Cryptosporidium
- The Company carried out a total of 1,108 tests on samples taken from three sites. Very low numbers of oocysts were detected in eight (0.72%) samples taken from two sites. All results were well below the treatment standard and there were no associated outbreaks of cryptosporidiosis.
Company Audit and Inspection
- The Company was inspected or audited by the Inspectorate or its appointed consultants on a number of occasions during 2001. Where relevant, report summaries are available in the 'Business and Technical' section of the web site under 'Audit and Inspection'.
Audit or Inspection Date Audit trails of five samples
July Audit of one water treatment works
July Audit of incident notification procedures February Audit of all Cryptosporidium sampling sites
Various dates during the year
Review of plumbosolvency treatment and control programmes of work
October
Review of progress with the distribution undertaking October
- Eight recommendations were made in respect of action required to avoid the risk of a breach of a regulatory duty. These recommendations were mainly in relation to the audit trails and inspection of the treatment works. o Four recommendations for improvement were made in respect of the plumbosolvency treatment for lead and the distribution undertaking.
Incidents
- The Inspectorate regarded one of the events notified during 2001 by the Company as an incident. For further details on the classification of incidents see Chapter C, 'Events affecting Water Quality', in Part 3.
- The incident has been assessed by the Inspectorate. It was of short duration and the Company took appropriate remedial action. Five recommendations were made to the Company regarding operations, sampling and analysis, and notification.
Nature of incident
No. of incidents Assessment completed by DWI Areas affected Supply of
discoloured
water
1 Yes Borras (August)
Improvement Programmes
- One remedial programme was due for completion during 2001. This was to improve treatment for coliforms at Boughton Treatment Works. This programme of work was completed ahead of schedule.
- The ongoing distribution system improvement programme has been progressing satisfactorily. During 2000 and 2001, 40 km of mains were renovated. The Company is required to renovate a further 76 km of mains by September 2004
- The Company has agreed programmes of work to meet the new and revised standards set down in the new Water Supply (Water Quality) Regulations 2000*, which will come into force on 25 December 2003. These relate to work required to meet the new standard for lead. Progress with delivery of the programmes is monitored by the Inspectorate, and has been satisfactory.
* The new Water Supply (Water Quality) Regulations 2001 for Wales.Enforcement Action
- No enforcement action for the company was considered as a result of the Inspectorate's activities during 2001.
table 6.1Dee Valley Water plc
MICROBIOLOGICAL QUALITY OF WATER LEAVING TREATMENT WORKS2001 2000 1999 Number of water treatment works 7 8 8 Works with no sampling shortfall 7 8 8 COLIFORMS Total number of determinations 1,352 1,376 1,405 - number containing coliforms 0 1 4 - % containing coliforms 0.0 0.1 0.3 Treatment works with coliforms detected 0 1 2 - % of all works 0.0 12.5 25.0 FAECAL COLIFORMS Total number of determinations 13,52 1,376 1,405 - number containing faecal coliforms 0 0 0 - % containing faecal coliforms 0.0 0.0 0.0 Treatment works with faecal coliforms detected 0 0 0 - % of all works 0 0 0
table 6.2 Dee Valley Water plc
MICROBIOLOGICAL QUALITY OF WATER IN SERVICE RESERVOIRS2001 2000 1999 Number of service reservoirs 30 31 31 Service reservoirs with no sampling shortfall 30 31 31 COLIFORMS Total number of determinations 1,569 1,580 1,612 - number containing coliforms 2 2 7 - % containing coliforms 0.1 0.1 0.4 Service reservoirs with coliforms detected 2 2 7 Service reservoirs with coliforms detected in more than 5% of samples 0 0 0 - % of all service reservoirs 0 0 0 FAECAL COLIFORMS Total number of determinations 1,569 1,580 1,612 - number containing faecal coliforms 1 2 0 - % containing faecal coliforms 0.1 0.1 0.0 Service reservoirs with faecal coliforms detected 1 2 0 - % of all service reservoirs 3.3 6.5 0
table 6.3 Dee Valley Water plc
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 2001. Column 'E' shows the number of zones for which new enforcement action is under consideration as a result of contraventions of the PCV in 2001. PARAMETER DETERMINATIONS in 2001 ZONES (18 in 2000)* Total Contravening PCV Non-compliant No. % CBU CBU E Number in: 2001 2001 2000 1999 Coliforms 807 0 0.0 0 0 0 0 0 0 Faecal coliforms 807 0 0.0 0 0 0 0 0 0 Colour 115 0 0.0 0 0 0 0 0 0 Turbidity 145 2 1.6 0 0 0 0 1 0 Odour 115 0 0.0 0 0 0 0 0 0 Taste 115 0 0.0 0 0 0 0 0 0 Hydrogen ion 595 0 0.0 0 0 0 0 0 0 Nitrate 115 0 0.0 0 0 0 0 0 0 Nitrite 201 8 4.0 0 0 0 4 1 3 Aluminium 153 0 0.0 0 0 0 0 1 1 Iron 239 1 0.4 0 0 0 1 3 1 Manganese 172 3 1.7 2 0 0 2 1 1 Lead 74 0 0.0 0 0 0 0 0 1 PAH 74 0 0.0 0 0 0 0 0 0 Trihalomethanes 74 0 0.0 0 0 0 0 0 0 Total pesticides 72 0 0.0 0 0 0 0 0 0 Other pesticides 1,514 0 0.0 0 0 0 0 0 0 All Others 1,804 0 0.0 0 0 0 0 0 0 TOTAL 7,191 12 0.2 2 - - - - - *18 Zones in 2000; 18 Zones in 1999 [ Previous ] [ Contents ] [ Next ]
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Drinking Water Inspectorate,
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Telephone : 020 7944 5956 - Facsimile : 020 7944 5969
E-mail: dwi.enquiries@defra.gsi.gov.uk
Published 10 July 2002
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