21 SUTTON AND EAST SURREY WATER PLC
Introduction
Sutton and East Surrey Water plc supplies on average about 152 Ml/d of water to about 634,000 consumers in the London Boroughs of Sutton, Croydon and Merton, and in parts of Surrey and Kent. 15% of the Company’s water supplies come from Bough Beech reservoir. The remainder comes from boreholes. The Company has nine treatment works, and distributes water through 3,374 km of pipes and 33 service reservoirs to 22 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 25,474 determinations in 2000. Of these, 99.61% demonstrated compliance with the relevant PCV, but 99 showed a contravention to have occurred.
Coliforms were not detected at any of the Company's nine 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 22 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 at six of its nine treatment works in 2000. Shortfalls at the other three are regarded as trivial and unlikely to recur.
Table 21.1 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 were detected are not considered significant.
There were no contraventions of the standards at any works.
Microbiological quality of water in service reservoirs
The Company complied with the sampling frequencies required by regulation 18 at 27 of its 33 service reservoirs in 2000. Shortfalls at the other six are regarded as trivial and unlikely to recur.
Table 21.2 shows the Company's performance in 2000, with data for 1999 and 1998 for comparison. Differences the last three years in the number of service reservoirs, and samples from service reservoirs, in which coliforms were detected are not considered significant.
There were no contraventions of the microbiological standards at any of the Company's service reservoirs in 2000.
Water quality in water supply zones
The Company complied with the required sampling frequencies for all parameters in all zones.
Table 21.3 shows the Company's performance in 2000, with data for 1999 and 1998 for comparison. Differences over the last three years are not considered statistically significant.
All contraventions of the standards in zones are considered trivial or unlikely to recur.
Inspection
Audit of plumbosolvency treatment and control programmes of work In November 2000, Consultants WS Atkins, represented by Mr S Ntifo, 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 Ntifo’s report Mr Halton concluded that:
the Company’s process of sites/scheme selection for plumbosolvency treatment and/or optimisation measures is sound;
the integrity of the data submitted to the Inspectorate and used for assessing plumbosolvency was confirmed;
the schemes audited are justified on water quality reasons; and
the Company’s proposed steps to be taken and the proposed completion dates are generally sound.
Audit trails of five samples
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:
Water quality has been monitored by appropriate techniques. There are a few improvements which could be made to sample handling and the AQC. With one exception, the Public Record has been maintained up to date.
Follow-up of response to recommendations
The Inspectorate audited the Company’s response to recommendations made during the 1999 inspection process and concluded that:
The Company has taken or is taking satisfactory action in respect of the recommendations made during the 1999 inspection;
The sampling arrangements are generally satisfactory, but there was too long a delay in resampling two of the samples;
The analytical results have appeared on the Public Record in time; and
Contraventions of regulation 3(3)(a) in respect of sampling were identified. However remedial action was to be taken speedily, so enforcement action was not necessary.
Review of procedures for operation and maintenance of the distribution network
In December 2000, Consultants Binnie, Black and Veatch working under the direction of Mr W M Waite, Principal Inspector carried a follow up investigation of the recommendations made during the 1999 audit of the Review of Procedures for Operation and Maintenance of the Distribution Network. Based on their report Mr Waite concluded that:The company responses cover most of the recommendations adequately but are considered inadequate in two areas, the flushing of large diameter mains and the routine monitoring of closed valves.
It is recommended that to provide adequate responses to those recommendations where the response has been considered inadequate, the company extend its procedures to provide the following:
Extension of its procedures to pay particular attention to the flushing of large diameter mains (Procedure and Practice for Flushing Small and Large Diameter Mains - Recommendation R4.2).
A procedure on the routine monitoring of the status of valves and on the condition of their markers (System for Classifying, Recording, Marking and Monitoring Valve Status - Recommendation R8.3).
The company addresses the issue of flushing large diameter mains but it is considered that the approach adopted requires more comprehensive guidance than is given to ensure flushing velocities are achieved.
The company has decided not to provide a specific procedure for the routine monitoring of closed valves and markers and therefore their response has been treated as inadequate. The company considers that their procedures for valve operations, reporting and recording changes in valve status and the operation of company wide district metering negate the need for the routine monitoring of valves.
Inspection of distribution system improvement programme progress In September 2000, Consultants Ewan Associates, represented by Mrs A Eggington & Mr G Shuker, working under the direction of Mr P Halton, Inspector, carried out an audit of the Company’s progress with the mains renovation set out in the distribution Undertaking submitted by the Company. Based on their report, Mr Halton concluded 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, 4 recommendations were conveyed to the Company for formal response.
Improvement programmes
One undertaking in respect of improvement programmes accepted by the Secretary of State from the Company was due for full completion or the completion of major steps during 2000 and it was completed on schedule.
The ongoing distribution system improvement programmes due for completion in 2005, which have been implemented by the Company, have been progressing satisfactorily.
Incidents
Neither of the events reported by the Company to the Inspectorate during 2000 were regarded as incidents in which drinking water quality demonstrably deteriorated.
Formal Cautions
During 2000, the assessment was completed of an incident which occurred in 1997 involving the supply of chalky water. The Company was formally cautioned for supplying water unfit for human consumption to parts of Morden in July 1997, contrary to Section 70 of the Water Industry Act 1991. The details of the offence will be kept on record and may be referred to, as appropriate, in the future.
Enforcement action
No enforcement action needed to be considered for the Company as a result of the Inspectorate's work in, or pertaining to, the calendar year 2000.
table 21.1 Sutton and East Surrey Water plc
MICROBIOLOGICAL QUALITY OF WATER LEAVING TREATMENT WORKS2000 1999 1998 Number of water treatment works 9 9 9 Works with no sampling shortfall 6 3 8 COLIFORMS Total number of determinations 2,279 2,317 2,463 - number containing coliforms 0 0 4 - % containing coliforms 0.0 0.0 0.2 Treatment works with coliforms detected 0 0 4 - % of all works 0 0 44 FAECAL COLIFORMS Total number of determinations 2,272 2,311 2,463 - 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 21.2 Sutton and East Surrey Water plc
MICROBIOLOGICAL QUALITY OF WATER IN SERVICE RESERVOIRS2000 1999 1998 Number of service reservoirs 33 34 35 Service reservoirs with no sampling shortfall 27 30 32 COLIFORMS Total number of determinations 1,768 1,787 1,862 - number containing coliforms 0 1 0 - % containing coliforms 0.0 0.1 0.0 Service reservoirs with coliforms detected 0 1 0 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 1,768 1,787 1,826 - 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 21.3 Sutton and East Surrey 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 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 (22 in 2000)* Total Contravening PCV Non-compliant No. % CBU CBU E Number in: 2000 2000 1999 1998 Coliforms 1,704 15 0.9 0 0 0 0 0 0 Faecal coliforms 1,704 1 <0.1 0 0 0 1 1 2 Colour 302 0 0.0 0 0 0 0 0 0 Turbidity 746 1 0.1 1 0 0 1 1 2 Odour 193 0 0.0 0 0 0 0 0 0 Taste 193 0 0.0 0 0 0 0 0 0 Hydrogen ion 1,704 0 0.0 0 0 0 0 0 0 Nitrate 302 0 0.0 0 0 0 0 0 0 Nitrite 492 78 15.9 0 0 0 5 5 8 Aluminium 326 0 0.0 0 0 0 0 1 0 Iron 378 1 0.3 1 0 0 1 3 6 Manganese 110 0 0.0 0 0 0 0 0 0 Lead 1,704 1 <0.1 0 0 0 1 1 1 PAH 112 0 0.0 0 0 0 0 0 0 Trihalomethanes 169 2 1.2 0 0 0 1 0 0 Total pesticides 208 0 0.0 0 0 0 0 0 0 Other pesticides 1,998 0 0.0 0 0 0 0 0 0 Tetrachloroethene 164 0 0.0 0 0 0 0 0 1 All others 4,878 0 0.0 0 0 0 0 0 0 TOTAL 17,387 99 0.6 2 - - - - - *22 zones in 1999; 23 zones in 1998.
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Drinking Water Inspectorate,
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Published 11 July 2001
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