3 BRISTOL WATER PLC
Introduction
Bristol Water plc supplies on average about 290 Ml/d of water to about 1,086,000 consumers in the Bristol conurbation and the surrounding parts of Somerset, Gloucestershire and Wiltshire. Up to 60% of the Company’s water supplies come from surface water abstracted from the River Severn via the Gloucestershire and Sharpness canal. Springs and surface water from impounding reservoirs in the Mendips supply between 25% and 45% of supply, depending upon available storage in the impounding reservoirs. The remainder comes from groundwater sources, springs, wells and boreholes (about 25% of supply). The Company has 15 treatment works on 15 sites, and distributes water through 6,500 km of pipes and 181 service reservoirs to 52 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 43,287 determinations in 2000. Of these, 99.90% demonstrated compliance with the relevant PCV, but 42 showed a contravention to have occurred.
Coliforms were not detected at 11 (73%) of the Company's 15 water treatment works. At all of the Company's 181 service reservoirs, coliforms were absent from at least 95% of samples. Of the Company's 52 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 its treatment works in 2000.
Table 3.1 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 one works has resulted in the consideration of enforcement action, as shown in table 3.4. 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 99 of its 181 service reservoirs in 2000. Shortfalls at the other 82 are regarded as trivial due to the fuel crisis and exceptional weather conditions preventing the samples being taken.
Table 3.2 shows the Company's performance in 2000, with data 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 in all zones.
Table 3.3 shows the Company's performance in 2000, with data 1999 and 1998 for comparison. Differences over the last three are not considered significant.
All contraventions of the standards in zones are considered or are covered by undertakings.
Inspection
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.
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.
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’s responses to all the recommendations are considered adequate and there are therefore no further recommendations arising from this follow up audit;
Inspection of distribution system improvement programme progress
In October 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 Mrs Eggington & Mr Shuker’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, four recommendations were conveyed to the Company.
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 2002, which have been implemented by the Company, have been progressing satisfactorily.
Incidents
None of the three events reported by the Company to the Inspectorate during 2000 were regarded as incidents in which drinking water quality demonstrably deteriorated.
Enforcement action
Table 3.4 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 3.1 Bristol Water Plc
MICROBIOLOGICAL QUALITY OF WATER LEAVING TREATMENT WORKS2000 1999 1998 Number of water treatment works 15 23 23 Works with no sampling shortfall 15 23 23 COLIFORMS Total number of determinations 3,037 3,438 3,580 - number containing coliforms 5 1 6 - % containing coliforms 0.2 >0.1 0.2 Treatment works with coliforms detected 4 1 5 - % of all works 27 4 22 FAECAL COLIFORMS Total number of determinations 3,035 3,438 3,580 - 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 3.2
MICROBIOLOGICAL QUALITY OF WATER IN SERVICE RESERVOIRS2000 1999 1998 Number of service reservoirs 181 183 186 Service reservoirs with no sampling shortfall 82 183 186 COLIFORMS Total number of determinations 9,117 9,169 9,193 - number containing coliforms 8 12 6 - % containing coliforms <0.1 0.1 0.1 Service reservoirs with coliforms detected 7 12 6 Service reservoirs with coliforms detected in more than 5% of samples 0 0 0 - % of all service reservoirs 0.0 0.0 0.0 FAECAL COLIFORMS Total number of determinations 9,117 9,169 9,193 - number containing faecal coliforms 2 2 1 - % containing faecal coliforms <0.1 <0.1 <0.1 Service reservoirs with faecal coliforms detected 2 2 1 - % of all service reservoirs 1.1 1 1
Sampling shortfalls at the service reservoirs were due to the fuel crisis and exceptional weather conditions.
table 3.3 Bristol Warter 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 (52 in 2000)* Total Contravening PCV Non-compliant No. % CBU CBU E Number in: 2000 2000 1999 1998 Coliforms 2,997 11 0.4 0 0 0 0 0 0 Faecal coliforms 2,997 0 0.0 0 0 0 0 1 0 Colour 240 0 0.0 0 0 0 0 0 0 Turbidity 260 0 0.0 0 0 0 0 0 0 Odour 253 0 0.0 0 0 0 0 0 0 Taste 241 0 0.0 0 0 0 0 0 0 Hydrogen ion 414 0 0.0 0 0 0 0 0 0 Nitrate 418 0 0 0 0 0 0 0 5 Nitrite 419 0 0.0 0 0 0 0 0 0 Aluminium 302 0 0.0 0 0 0 0 0 0 Iron 556 3 0.5 2 20 0 3 5 5 Manganese 451 0 0.0 0 0 0 0 1 0 Lead 212 0 0.0 0 0 0 0 0 0 PAH 303 13 4.3 9 13 0 8 10 7 Trihalomethanes 162 0 0.0 0 0 0 0 0 0 Total pesticides 337 0 0.0 0 0 0 0 0 0 Other pesticides 1,512 0 0.0 0 0 0 0 0 0 All others 6,907 0 0.0 0 0 0 0 0 0 TOTAL 18,981 27 0.14 11 - - - - - *52 zones in 1999; 52 zones in 1998.
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Published 11 July 2001
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