Water quality at treatment works, in service reservoirs and in water supply zones

To be wholesome, water must comply with the water quality standards for the parameters set out in the Water Supply (Water Quality) Regulations 1989. In 2003, the Company carried out a total of 46,817 tests on samples of water leaving its 17 water treatment works, from its 185 service reservoirs and from consumers’ taps in its 52 water supply zones. Of these, 99.93% (46,783) complied with the standards set down in the Regulations. However, 0.07% (34) tests did not meet the standards. A list of the parameters, the relevant standards and their significance can be found at the beginning of this section.

Water quality leaving treatment works

A comparison of the Company’s performance in 2003 with data for 2002 and 2001, is given below. Differences over the last three years in the number of treatment works, and in the number of tests carried out on samples from treatment works, in which coliforms or faecal coliforms were detected, were not considered significant.

During 2003, the single failure of the total coliform standard at one works was considered trivial, or unlikely to recur.

No failures of the faecal coliform standard occurred at any works.

In 2003, 1,632 regulatory samples for Cryptosporidiu m were taken at five sites. Very low numbers of oocysts were detected in 24 samples from three sites. All results were well below the treatment standard and there were no reported outbreaks of cryptosporidiosis associated with drinking water.

Water quality in service reservoirs

A comparison of the Company’s performance in 2003 with data for 2002 and 2001, is given below. In 2002, there was a significant increase in the number of service reservoirs in which total coliforms were detected. However, differences since 2002 in the number of service reservoirs, and in the number of tests carried out on samples from service reservoirs, in which coliforms or faecal coliforms were detected, were not considered significant.

During 2003, total coliforms were detected at a number of service reservoirs. However, there was no failure of the total coliform standard at any service reservoir.

The three failures of the faecal coliform standard at three service reservoirs were considered trivial or unlikely to recur.

Water quality in water supply zones

The table below shows the data for the key parameters and any other parameters where there was a failure of the standard. All other parameters were fully compliant. A comparison is also given for parameters failing the standards in 2002 and 2001.

Parameter	Total number of tests	Tests not meeting standard		Number of failures covered by Undertakings	Number of zones not complying with the standards (number of zones in 2003 = 52)*
		No	%		2003	2002	2001
Coliforms	3,087	9	0.29	0	0	0	0
Faecal coliforms	3,087	2	0.06	0	2	1	2
Colour	249	0	0.00	0	0	0	0
Turbidity	247	0	0.00	0	0	0	0
Odour	256	1	0.39	0	1	0	0
Taste	256	1	0.39	0	1	0	0
Hydrogen ion	418	0	0.00	0	0	0	0
Nitrate	425	0	0.00	0	0	0	0
Nitrite	425	0	0.00	0	0	0	0
Aluminium	333	0	0.00	0	0	1	0
Iron	490	2	0.41	2	1	4	2
Manganese	429	1	0.23	0	1	0	1
Lead	217	1	0.46	0	1	0	0
PAH	274	5	1.82	0	3	6	10
Trihalomethanes	191	0	0.00	0	0	0	0
Total pesticides	382	0	0.00	0	0	0	0
Other pesticides	1,805	0	0.00	0	0	0	0
All others	7,112	0	0.00	0	0	0	0
TOTAL	19,683	22	0.11
*52 zones in 2002 and in 2001

The fifth column indicates the number of failures in zones already covered by legally binding undertakings given by the Company. These undertakings require remedial work to be carried out to ensure compliance with the individual standard.

There have been improvements in compliance with the iron and PAH parameters reflecting improvements to the Company’s mains distribution system completed in 2002.

The new Regulations

In 2003, the Company carried out monitoring for the six new parametric values set down in the new Water Supply (Water Quality) Regulations 2000. These Regulations came into force on 25 December 2003. The results are shown in the table below.

Parameter	Total number	New standard	Tests not meeting
	of tests		the new standard
Benzene	89	1.0 µg/l	0
Bromate	1,615	10.0 µg/l	3*
1,2 dichloroethane	371	3.0 µg/l	0
Nitrite (exwater treatment works)	1,615	0.1 mg/l	0
Clostridium perfringens	204	0/100 ml	0
Enterococci	834	0/100 ml	0

*These results occurred early in 2003 and relate to water leaving one water treatment works. The Company took immediate action and there have been no subsequent results that have not met the new standard.

Compliance data for 2003 have also been analysed against the revised standards and the results are shown in the following table.

Parameter	Total number of tests	Current Standard	Number of tests not meeting current standard	Revised Standard	Number of tests not meeting revised standard
Antimony	53	10.0 µg/l	0	5.0 µg/l	0
Arsenic	131	50.0 µg/l	0	10.0 µg/l	0
Boron	53	2.0 mg/l	0	1.0 mg/l	0
Copper	52	3.0 mg/l	0	2.0 mg/l	0
Lead	217	50.0 µg/l	1	25.0 µg/l	1
				10.0 µg/l*	7
Nickel	53	50.0 µg/l	0	20.0 µg/l	0
Nitrite (at consumers taps)	425	0.1 mg/l	0	0.5 mg/l	0
PAH	274	0.2 µg/l	5	0.1 µg/l	0
Tetrachloroethene Trichloroethane	191 191	10.0 µg/l 30.0 µg/l	0 0	} 10.0 µg/l	0
* Final standard not applicable until 2013

Details of the new and revised standards can be found in chapter J ‘New Regulations and Associated Programmes of Work’.

Audit and inspection

The Company was inspected or audited by the Inspectorate or its appointed consultants on a number of occasions during 2003. Where relevant, report summaries are available in the ‘Business and Technical’ section of the Inspectorate’s website under ‘Audit and Inspection’. Details of the subject areas audited or inspected are given in the following paragraphs:

Follow up of recommendations made during the 2002 inspections or in connection with water quality incidents

Steps have been taken to implement all of the recommendations arising from the 2002 audit and inspection process and from assessments of water quality incidents.

Audit of regulatory Cryptosporidium monitoring sites

The monitoring equipment at all regulatory sites visited during the year was found to be satisfactory.

Audit of regulatory Cryptosporidium samplers

The audit of one of the samplers responsible for taking regulatory Cryptosporidium samples was satisfactory.

Inspection of laboratory analysing for Cryptosporidium

The announced audit on the Company’s Cryptosporidiu m laboratory identified four regulatory breaches as well as a number of other minor deficiencies associated with the analysis of regulatory samples. The Company’s laboratory has taken remedial action to rectify the deficiencies identified.

An unannounced audit on the Company’s Cryptosporidiu m laboratory was satisfactory.

Audit of membrane treatment plants and membrane integrity testing system

An audit of one membrane treatment site and the system of membrane integrity testing was found to be satisfactory.

Audit of progress with water treatment works improvement programmes

A desktop audit of three schemes associated with improvement programmes at water treatment works was carried out together with site visits. The schemes were for arsenic at Barrow treatment works, bromate at Littleton treatment works and Cryptosporidium at Chelvey treatment works. Progress with most of the schemes was considered satisfactory. However, the scheme for arsenic at Barrow has been delayed due to planning permission issues which are beyond the control of the Company.

Review of distribution system undertaking

Progress with the programme of mains renovation set out in the Company’s distribution system undertaking was found to be satisfactory.

Audit trails of selected microbiological test results

Vertical audits were carried out on two test results selected at random for the period September 2002 to January 2003. The Company is being required to take action on deficiencies identified with recording of analytical times on both samples and updating its method and the control value on the second sample.

Audit trails of selected nonmicrobiological test results

Vertical audits were carried out on eight test results selected at random for the period July 2002 to June 2003. The Company is being required to take action on deficiencies identified with the record of an analysis carried out by its contract laboratory and instrument records and construction of the control chart relating to another sample.

Inspection of two water treatment works and two service reservoir

Inspections were carried out at Cheddar and Stowey water treatment works and at Durdham Down Tower and Durdham Down service reservoir sites. The operation and management of the treatment works and the service reservoir were satisfactory. However, the Company was required to take, and has completed, action on two deficiencies associated with sampling and maintenance at the water tower.

Audit of sampling arrangements

An audit carried out on one sample round was satisfactory except for a deficiency in the sampling facilities at Purton water treatment works. The Company has taken action to improve this.

Audit of plumbosolvency treatment and control programmes

Progress with the programme of work for plumbosolvency treatment and control measures for lead was found to be satisfactory.

Audit of procedures relating to mains operations by company and contract staff

Audits of Company procedures were found to be satisfactory.

Incidents

The Inspectorate regarded five events notified during 2003 as incidents. Further details of these incidents are given in the table below.

Two of the incidents were fully investigated and assessed by the Inspectorate during 2003. Each was of relatively short duration and, where applicable, the Company took appropriate action to protect public health. The Company is being required to take action on a number of deficiencies identified in respect of carrying out risk assessments, internal communications, site supervision and training, notifying consumers and sampling. The remaining three incidents are under consideration.

Enforcement action

No enforcement action was considered for the Company as a result of the Inspectorate’s activities in 2003.

Improvement programmes

Water treatment works/service reservoirs

No improvement programmes at water treatment works or service reservoirs were due for completion during 2003.

Distribution

Work for the Company’s distribution system undertaking is largely complete. During 2003, three kilometres of mains were renovated. The Company is required to complete one small scheme by 30 June 2004.

Lead

The Company’s Regulation 41 programme of work to meet the revised standard for lead set down in the new Water Supply (Water Quality) Regulations 2000 has been progressing satisfactorily. Plumbosolvency treatment measures were installed at all four sites specified in the programme by 25 December 2003.