Three Valleys Water PLC
Overall Water Quality supplied by Three Valleys Water in 2000
A total of 82,027 tests were carried out by Three Valleys Water in 2000. Of these tests, 99.88% complied with the Regulations.
Company Information Amount of Water Supplied: 699 Ml/d Consumers Supplied: 2.4 million Areas of Supply: Parts of Bedfordshire, Berkshire, Buckinghamshire, Essex, Hertfordshire and several London Boroughs Water Composition: 33% from rivers and reservoirs 67% from boreholes and aquifers Treatment Works: 77 Service Reservoirs: 117 Km of Mains: 11,000 Water Supply Zones: 98 Water Quality in Water Supply Zones, at Treatment Works, and in Service Reservoirs
Water supply zones
- In general, to be wholesome, water must comply with the standards set out in the Regulations. The Company carried out a total of 54,457 tests on samples taken in its 98 water supply zones. The table below includes only the parameters that breached the standard. All other parameters fully complied with the standards. Parameter meanings 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 to carry out remedial works to overcome the difficulty in meeting the individual standard.
Parameter
Total samples taken
Samples not meeting the standard
Percentage
Number of failures already covered by undertakings
Total coliforms
6,798
34
0.50
-
Faecal coliforms
6,798
1
0.01
-
Turbidity
5,888
3
0.05
2
Nitrite
787
22
2.80
-
Iron
1,726
5
0.29
3
Lead
520
5
0.96
-
PAH
246
4
1.63
-
Atrazine
409
3
0.73
-
Treatment works
Of the Company’s 77 treatment works, 69 (90%) complied fully with the relevant standards.
Contraventions at the other eight treatment works were considered trivial and unlikely to recur. Differences over the last three years in the number of treatment works, and samples from treatment works, in which coliforms were detected are not considered significant.Service reservoirs
Failures of the standard for faecal coliforms at a one service reservoir were considered trivial and unlikely to recur. There have been significant decreases over the last three years in the number of service reservoirs, and samples from service reservoirs, in which total coliforms were detected. All other differences are not considered significant.
- At all of the Company's 117 service reservoirs, coliforms were absent from at least 95% of samples.
Company Audit and Inspection
Link to expanded information (web site version)Where relevant, report summaries are available in the ‘Business and Technical’ section of DWI’s web site under ‘Audit and Inspection’.
- The Company was inspected or audited by DWI or its appointed consultants on five occasions in 2000.
Audit or Inspection
Date
Annual assessment of 1999 compliance data.
April / May
Follow-up of response to recommendations and audit of arrangements for Cryptosporidium sampling
October
Audit of plumbosolvency treatment and control programs of work
November
Audit trails of five samples
November
Inspection of distribution system improvement programme progress.
Ongoing
- A number of recommendations for improvements were made, especially in relation to analytical arrangements and Cryptosporidium sampling arrangements.
Incidents
- The Inspectorate regarded nine of the events notified during 2000 by the Company as incidents in which drinking water quality demonstrably deteriorated.
- All of the incidents have been assessed by DWI. Each was of short duration and the Company has taken appropriate remedial action. Two recommendations were made to the Company regarding sampling and procedures and a formal caution was issued in respect of one incident. For further information please see ‘Events affecting Water Quality’ in Part 3.
- During 2000, assessment was also completed for one incident which occurred in 1999.
Nature of Incident
No. of Incidents
Assessment by DWI Completed
Areas Affected
Supply of discoloured water
3
Yes
Watford(January), Ongar, Moreton, High Laver, Matching Green and Fyfield (March), Kings Langley (April).
Wholesomeness concerns following bacteriological failures
4
Yes
Watford (June), Watton at Stone (July), Wembley (August), and Whetstone (October).
Loss of supply
1
Yes
Eaton Bray (March).
Contamination of source
1
Yes
Hatfield (June).
Improvement Programmes
Carried Out by the Company
- No remedial programmes were due for full completion during 2000.
- The distribution system improvement programme, due for completion in 2008, is on-going. The Inspectorate is in discussions with the Company concerning the volume of work required.
Enforcement Action
- No enforcement action needed to be considered for the Company as a result of the Inspectorate’s work during 2000.
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Drinking Water Inspectorate,
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Telephone : 020 7944 5956 - Facsimile : 020 7944 5969
E-mail: dwi_enquiries@detr.gov.uk
Published 11 July 2001
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