4 CAMBRIDGE WATER COMPANY
Introduction
Cambridge Water supplies on average about 70 Ml/d of water to about 291,700 consumers in the city of Cambridge and surrounding areas. All of the Company’s water supplies come from 25 ground water sources, of which 22 are deep chalk boreholes (about 97 % of the supply); two are from greensand aquifers (about 2% of supply) and one from river gravels (about 1% of supply). The Company also receives a small bulk supply of treated water from Three Valleys Water Services into a discrete water supply zone. The Company has 23 treatment works on 23 sites, and distributes water through 2,194 km of pipes and 33 service reservoirs and towers to 14 water supply zones.
Overall water quality
At water treatment works and service reservoirs and in water supply zones, the Company carried out a total of 11,206 determinations in 2000. Of these, 99.81% demonstrated compliance with the relevant PCV, but 21 showed a contravention to have occurred.
Coliforms were not detected at 18 (78%) of the Company's 23 water treatment works. At all of the Company's 33 service reservoirs, coliforms were absent from at least 95% of samples. Of the Company's 14 water supply zones in 2000, all complied fully with the relevant water quality standards or had breaches of the standards which were either trivial or were fully covered by undertakings.
Microbiological quality of water leaving treatment works
The Company complied with the sampling frequencies required by regulation 17 all its treatment works in 2000.
Table 4.1 shows the Company's performance in 2000, with data for 1999 and 1998 for comparison. 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 are not considered significant.
Contraventions of the microbiological quality standards at a total of 2 works have resulted in the consideration of enforcement action, as shown in table 4.4. 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 2000.
Table 4.2 shows the Company's performance in 2000, with data for 1999 and 1998 for comparison. Differences in the last three years in the number of service reservoirs, and samples from service reservoirs, in which coliforms or faecal coliforms were detected are not considered significant.
All contraventions of the standards at service reservoirs are considered trivial.
Water quality in water supply zones
The Company complied with the required sampling frequencies for all parameters in all zones.
Table 4.3 shows the Company's performance in 2000, with data for 1999 and 1998 for comparison. Differences over the last three are not considered statistically significant.
All contraventions of the standards in zones are considered trivial.
Inspection
Investigation of computer systems and associated data management for drinking water quality information appearing on the Public Record Part of the 2000 inspection of Cambridge Water Company was carried out by Messrs Milsom and Hughes of DERA, consultants working under the supervision of Mr W M Waite, Principal Inspector. On the basis of their inspection, which was held in March 2000, DERA concluded that:
administration of the supervisor accounts had significant deficiencies;
This was balanced by a generally good approach to security;
There were also some concerns about audit trail integrity and archiving, but correcting these should require only a modest effort.
Audit trails of five samples
In October 2000, Mr R M Walls, Consultant, working under the direction of Mr W M Waite, Principal Inspector carried out audit trails on five samples chosen at random. Based on Mr Walls report Mr Waite concluded that:
The sampling and analytical arrangements are generally satisfactory. The analytical results have, with one exception, appeared on the Public Record in time.
Audit of plumbosolvency treatment and control programmes of work
In November 2000, Consultants WS Atkins, represented by Mr M Kimber, working under the direction of Mr P Halton, Inspector, carried out an audit of the Company as part of the Inspectorate’s work in agreeing with water companies’ their programmes of works to secure compliance with new lead standards. Based on Mr Kimber’s report, Mr Halton concluded that:
for the schemes audited, the data supporting the inclusion of the schemes is generally sound.
there is sufficient justification to support audited schemes in the programme of work.
the Company currently had insufficient data on which to base a decision for each audited scheme.
the Company may not meet its target completion dates.
As a result of these inspections, 14 recommendations were conveyed to the Company for formal response, the majority relating to data management. Five suggestions on data management were also made. The Company is taking action or has already taken action on all of the recommendations.
Improvement programmes
The Company has no undertakings in place in respect of improvement programmes.
Relaxations
The Secretary of State had authorised a relaxation of a PCV, subject to review by 31 December 1999. This related to potassium in all zones supplied from the Croydon borehole. As a result of the review initiated by the Inspectorate in November 1999 the relaxation has been renewed subject to review by 25 December 2003.
Incidents
No events regarded as constituting incidents in which drinking water quality demonstrably deteriorated came to the attention of the Inspectorate in 2000.
Enforcement action
Table 4.4 summarises enforcement action under consideration for the Company as a result of the Inspectorate's work in, or pertaining to, the calendar year 2000.
table 4.1 Cambridge Water Company
MICROBIOLOGICAL QUALITY OF WATER LEAVING TREATMENT WORKS2000 1999 1998 Number of water treatment works 23 23 23 Works with no sampling shortfall 23 23 23 COLIFORMS Total number of determinations 1,647 1,532 1,779 - number containing coliforms 7 3 0 - % containing coliforms 0.4 0.2 0.0 Treatment works with coliforms detected 5 3 0 - % of all works 22 13 0 FAECAL COLIFORMS Total number of determinations 1,647 1,532 1,779 - 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 4.2 Cambridge Water Company
MICROBIOLOGICAL QUALITY OF WATER IN SERVICE RESERVOIRS2000 1999 1998 Number of service reservoirs 33 34 34 Service reservoirs with no sampling shortfall 33 34 34 COLIFORMS Total number of determinations 1,716 1,752 1,774 - number containing coliforms 5 9 5 - % containing coliforms 0.3 0.5 0.3 Service reservoirs with coliforms detected 5 6 5 Service reservoirs with coliforms detected in more than 5% of samples 0 1 0 - % of all service reservoirs 0 3 0 FAECAL COLIFORMS Total number of determinations 1,716 1,752 1,774 - number containing faecal coliforms 0 0 0 - % containing faecal coliforms 0.0 0.0 0.0 Service reservoirs with faecal coliforms detected 0 0 0 - % of all service reservoirs 0 0 0
table 4.3 Cambridge Water Company
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 2000. Column 'E' shows the number of zones for which new enforcement action is under consideration as a result of contraventions of the PCV in 2000. Please refer to the Introduction to Part 2 for more detailed explanation of this table. PARAMETER DETERMINATIONS in 2000 ZONES (14 in 2000)* Total Contravening PCV Non-compliant No. % CBU CBU E Number in: 2000 2000 1999 1998 Coliforms 854 7 0.8 0 0 0 0 0 0 Faecal coliforms 854 0 0.0 0 0 0 0 0 0 Colour 90 0 0.0 0 0 0 0 0 0 Turbidity 90 0 0.0 0 0 0 0 0 0 Odour 97 0 0.0 0 0 0 0 0 0 Taste 97 0 0.0 0 0 0 0 0 0 Hydrogen ion 90 0 0.0 0 0 0 0 0 0 Nitrate 134 0 0.0 0 0 0 0 0 0 Nitrite 93 0 0.0 0 0 0 0 0 0 Aluminium 95 0 0.0 0 0 0 0 0 0 Iron 142 1 0.7 0 0 0 1 1 0 Manganese 90 0 0.0 0 0 0 0 0 0 Lead 39 0 0.0 0 0 0 0 0 0 PAH 95 1 1.0 0 0 0 1 1 2 Trihalomethanes 40 0 0.0 0 0 0 0 0 0 Total pesticides 14 0 0.0 0 0 0 0 0 1 Other pesticides 392 0 0.0 0 0 0 0 0 0 Potassium 41 0 0.0 0 0 0 0 0 1 All others 1,133 0 0.0 0 0 0 0 0 0 TOTAL 4,480 9 0.20 0 - - - - - *14 zones in 1999; 14 zones in 1998
table 4.4 Cambridge Water Company
SUMMARY OF ENFORCEMENT ACTION CONSIDERED IN 2000Regulation Reason for enforcement 3(7) Contravention of the coliform standard at two reatment works.
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Published 11 July 2001
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