19 SOUTH WEST WATER SERVICES LIMITED
Introduction
South West Water Ltd supplies on average about 446 Ml/d of water to about 1.5 million consumers in an area approximating to the counties of Devon and Cornwall. Approximately 90% of the Company’s water supplies come from surface water sources. The remaining 10% comes from boreholes. The Company has 36 treatment works, and distributes water through 15,000 km of pipes and 351 service reservoirs to 81 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 118,951 determinations in 2000. Of these, 99.85% demonstrated compliance with the relevant PCV, but 179 showed a contravention to have occurred.
Coliforms were not detected at 26 (72%) of the Company's 36 water treatment works. At 349 (99%) of the Company's 351 service reservoirs, coliforms were absent from at least 95% of samples. Of the Company's 81 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 all of its treatment works in 2000.
Table 19.1 shows the Company's performance in 2000, with data for 1999 and 1998 for comparison. There has been a significant increase since 1999 in the number of treatment works in which coliforms were detected. All other differences at treatment works are not considered significant.
All contraventions of the standards at works are considered trivial or unlikely to recur.
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 19.2 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 were detected are not considered significant.
All contraventions of the standards at service reservoirs are considered trivial or unlikely to recur as a result of action taken by the Company.
Water quality in water supply zones
The Company complied with the required sampling frequencies for all parameters in all zones.
Table 19.3 shows the Company's performance in 2000, with data for 1999 and 1998 for comparison. There has been a significant reduction since 1999 in the number of zones failing to comply with the standard for PAH. All other differences in zones are not considered significant.
All contraventions of the standards in zones are considered trivial or unlikely to recur as a result of actions taken by the Company, or are covered by undertakings.
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 recent data submitted to the Inspectorate and used for assessing plumbosolvency needs was generally confirmed;
of the schemes audited some of the schemes are justified on water quality reasons for inclusion in the Company’s programme of works for plumbosolvency measures; 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:
The sampling and analytical arrangements are generally satisfactory, although the method for manganese may not be reliable enough. The analytical results have appeared on the Public Record in time. The Company’s response to breaches of the PCV is not as rapid as it might be.
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:
that to provide adequate responses to those responses to recommendations that are considered inadequate, the company extend its procedures to provide the following:
- For mains isolation for burst repair, guidance should be given on the impact assessment of alternative supplies and liaison with other company departments to avoid activity conflicts (Procedure for the Routine Operation of Valves – Recommendation R2.1);
- Guidance on the removal of air during recharging of mains following completion of the maintenance or repair, on the flushing locations, on flushing discharge rates, on timing as to when the main should be brought back into service and on the speed of valve operation (Procedure for the Routine Operation of Valves – Recommendation R2.2 and Avoidance of Rapid Fluctuations in Flow that Could Disturb Sediment – Recommendation R9.1);
- Guidance on pre planning flushing operations including selection criteria, network model assessment, diameter limit for flushing, flushing velocities, valving to concentrate flows, flushing sequence, timing of operation and consumers affected (Policy for the Pre-emptive Flushing of mains and its Implementation – Recommendation R3.1);
- Guidance on the notification which should accompany pre-emptive flushing operations including consumers affected, local authorities and within the company itself (Policy for the Pre-emptive Flushing of mains and its Implementation – Recommendation R3.2);
- Guidance on the implementation and monitoring of pre-emptive flushing operations to include a written statement, hydrant flushing durations and sampling requirements (Policy for the Pre-emptive Flushing of mains and its Implementation – Recommendation R3.3);
- Guidance on the maximum diameter of main that can be flushed by normal means (Procedure and Practice for Flushing Small and Large Diameter Mains – Recommendation R4.1);
- Guidance on the difficulties of flushing large diameter mains and on effective procedures for doing so (Procedure and Practice for Flushing Small and Large Diameter Mains – Recommendation R4.2);
- Guidance on the assessment of potential discolouration problems from major pre planned operations through the application of network modelling (Use of Computer Modelling and Other Techniques to Assess Potential Discolouration Problems from Pre Planned Operations – Recommendation R7.1);
- A system for routinely monitoring the status of valves and the condition of their site markers (System for Classifying, Recording, Marking and Monitoring Valve Status – Recommendation R8.1)
Inspection of distribution system improvement programme progress
In August 2000, Consultants Parkman Ltd, represented by Mr G Carlisle, 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 Mr Carlisle’s 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, 14 recommendations were conveyed to the Company for formal response. The Company is taking action or has already taken action on all of the recommendations.
Improvement programmes
No undertakings in respect of improvement programmes accepted by the Secretary of State from the Company were due for full completion or the completion of major steps during 2000.
The ongoing distribution system improvement programmes due for completion in 2010, which have been implemented by the Company, have been progressing satisfactorily.
Incidents
Seven events notified during 2000 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. Six of the incidents have been assessed by DWI. Each was of short duration and the Company took remedial action. One was due to the supply of discoloured water in Paignton, three involved loss of supply Exeter and Bude in October and Heybrook Bay in April, one was due to taste and odour, one was due to microbiological failures in distribution and one involved the issue of advice following a burst. Ten recommendations were made to the Company mainly regarding operations and procedures.
One assessment from the year 2000 remains outstanding.
No other events regarded as constituting incidents came to the attention of the Inspectorate in 2000.
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 19.1 South West Water Services Limited
MICROBIOLOGICAL QUALITY OF WATER LEAVING TREATMENT WORKS2000 1999 1998 Number of water treatment works 36 40 41 Works with no sampling shortfall 36 40 41 COLIFORMS Total number of determinations 8,085 8,289 8,337 - number containing coliforms 10 4 12 - % containing coliforms 0.1 <0.1 0.1 Treatment works with coliforms detected 10 3 11 - % of all works 27.8 8 27 FAECAL COLIFORMS Total number of determinations 8,086 8,289 8,342 - number containing faecal coliforms 1 1 3 - % containing faecal coliforms <0.1 <0.1 <0.1 Treatment works with faecal coliforms detected 1 1 1 - % of all works 2.8 2 7
table 19.2 South West Water Services Limited
MICROBIOLOGICAL QUALITY OF WATER IN SERVICE RESERVOIRS2000 1999 1998 Number of service reservoirs 351 346 348 Service reservoirs with no sampling shortfall 351 346 348 COLIFORMS Total number of determinations 18,495 18,862 18,949 - number containing coliforms 35 31 27 - % containing coliforms 0.2 0.2 0.1 Service reservoirs with coliforms detected 30 28 26 Service reservoirs with coliforms detected in more than 5% of samples 2 1 0 - % of all service reservoirs 0.6 <0.1 0 FAECAL COLIFORMS Total number of determinations 18,510 18,862 18,961 - number containing faecal coliforms 5 6 5 - % containing faecal coliforms <0.1 <0.1 <0.1 Service reservoirs with faecal coliforms detected 5 6 5 - % of all service reservoirs 1.4 2 1
table 19.3 South East Water Services Limited
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 (81 in 2000)* Total Contravening PCV Non-compliant No. % CBU CBU E Number in: 2000 2000 1999 1998 Coliforms 4,701 16 0.3 0 0 0 0 0 0 Faecal coliforms 4,702 2 <0.1 0 0 0 2 3 3 Colour 2,625 0 0.0 0 0 0 0 0 0 Turbidity 2,622 1 <0.1 0 4 0 1 8 1 Odour 755 0 0.0 0 0 0 0 0 0 Taste 754 0 0.0 0 0 0 0 0 1 Hydrogen ion 2,623 3 0.1 0 3 0 3 6 2 Nitrate 1,160 0 0.0 0 0 0 0 0 0 Nitrite 1,160 0 0.0 0 0 0 0 0 1 Aluminium 2,628 0 0.0 0 0 0 0 1 0 Iron 2,626 75 2.9 70 81 0 37 39 45 Manganese 2,628 8 0.3 6 81 0 8 9 14 Lead 432 3 0.7 3 4 0 2 3 6 PAH 412 20 4.9 17 51 0 11 27 28 Trihalomethanes 331 0 0.0 0 0 0 0 0 0 Total pesticides 464 0 0.0 0 0 0 0 0 0 Other pesticides 16,506 0 0.0 0 0 0 0 0 0 All others 18,646 0 0.0 0 0 0 0 0 0 TOTAL 65,775 128 0.2 96 - - - - - *81 zones in 1999; 82 zones in 1998.
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Published 11 July 2001
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