Chief Inspector's Report 2002
14 Severn Trent Water Limited
| Overall Water Quality supplied by Severn Trent Water Limited in 2002 | |||||||||||||||||||||||
|
|||||||||||||||||||||||
|
|
||||||||||||||||||||||
Water Quality at Treatment Works, in Service Reservoirs and in Water Supply Zones
To be wholesome, water must comply with the standards for the parameters set out in the Water Supply (Water Quality) Regulations 1989. In 2002, the Company carried out a total of 282,799 tests on samples taken at water treatment works, from service reservoirs and in water supply zones and of these, 99.91% complied with the relevant water quality standards set down in the Regulations. 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
2002 |
2001 |
2000 |
||
| Number of water treatment works | 162 |
179 |
164 |
|
| COLIFORMS | ||||
| Total number of tests | 15,009 |
14,551 |
15,571 |
|
| - | number containing coliforms | 15 |
9 |
15 |
| - | % containing coliforms | 0.10% |
0.06% |
0.10% |
| Treatment works with coliforms detected | 10 |
7 |
11 |
|
| - | % of all works with coliforms detected | 6.17% |
3.91% |
6.71% |
| FAECAL COLIFORMS | ||||
| Total number of tests | 15,009 |
14,551 |
15,571 |
|
| - | number containing faecal coliforms | 1 |
1 |
0 |
| - | % containing faecal coliforms | 0.01% |
0.01% |
0.00% |
| Treatment works with faecal coliforms detected | 1 |
1 |
0 |
|
| - | % of all works with faecal coliforms detected | 0.62% |
0.56% |
0.00% |
Failures of the coliform standard at nine works in 2002 were considered trivial. Coliform and faecal coliform failures at the remaining treatment works are covered by an undertaking. 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.
In 2002, 2,908 regulatory samples for Cryptosporidium were taken at eight sites. Very low numbers of oocysts were detected in 15 samples from five sites. All results were well below the treatment standard and there were no reported outbreaks of cryptosporidiosis.
Water Quality in Service Reservoirs
2002 |
2001 |
2000 |
||
| Number of service reservoirs | 605 |
623 |
614 |
|
| COLIFORMS | ||||
| Total number of tests | 31,213 |
31,324 |
31,241 |
|
| - | number containing coliforms | 32 |
45 |
44 |
| - | % containing coliforms | 0.10% |
0.14% |
0.14% |
| Service reservoirs with coliforms detected | 32 |
39 |
37 |
|
| Service reservoirs with coliforms detected | 0 |
0 |
0 |
|
| in more than 5% of tests | ||||
| - | % of all service reservoirs with coliforms detected | 0.00% |
0.00% |
0.00% |
| FAECAL COLIFORMS | ||||
| Total number of tests | 31,213 |
31,324 |
31,241 |
|
| - | number containing faecal coliforms | 6 |
3 |
4 |
| - | % containing faecal coliforms | 0.02% |
0.01% |
0.01% |
| Service reservoirs with faecal coliforms detected | 6 |
3 |
4 |
|
| - | % of all service reservoirs with faecal coliforms detected | 0.99% |
0.48% |
0.65% |
The failures of the coliform standard at 32 service reservoirs were considered trivial. The Company is taking action towards preventing failure recurring at six of these service reservoirs. Differences over the last three years 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.
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.
| Parameter | Total number of tests |
Tests not meeting the prescribed concentration or value |
Number of failures covered by Undertakings |
Number of zones not complying with the standards |
|||
No |
% |
2002 |
2001 |
2000 |
|||
| Coliforms | 19,598 |
93 |
0.47 |
23 |
0 |
0 |
0 |
| Faecal coliforms | 19,598 |
5 |
0.00 |
1 |
5 |
5 |
5 |
| Colour | 1,307 |
0 |
0.00 |
0 |
0 |
0 |
0 |
| Turbidity | 4,571 |
0 |
0.00 |
0 |
0 |
0 |
3 |
| Odour | 1,116 |
0 |
0.00 |
0 |
0 |
0 |
0 |
| Taste | 1,262 |
0 |
0.00 |
0 |
0 |
0 |
1 |
| Hydrogen ion | 1,554 |
0 |
0.00 |
0 |
0 |
0 |
0 |
| Nitrate | 5,287 |
1 |
0.02 |
0 |
1 |
1 |
0 |
| Nitrite | 1,542 |
5 |
0.32 |
0 |
3 |
2 |
2 |
| Aluminium | 1,589 |
1 |
0.06 |
0 |
1 |
3 |
2 |
| Iron | 5,619 |
37 |
0.66 |
16 |
25 |
23 |
20 |
| Manganese | 1,611 |
7 |
0.43 |
0 |
3 |
1 |
3 |
| Lead | 721 |
4 |
0.55 |
0 |
4 |
3 |
2 |
| PAH | 1,133 |
40 |
3.53 |
0 |
21 |
20 |
17 |
| Trihalomethanes | 684 |
0 |
0.00 |
0 |
0 |
0 |
0 |
| Total pesticides | 861 |
0 |
0.00 |
0 |
0 |
0 |
0 |
| Other pesticides | 54,794 |
0 |
0.00 |
0 |
0 |
0 |
0 |
| Benzo 3,4 Pyrene | 1,127 |
1 |
0.09 |
0 |
0 |
0 |
0 |
| Sulphate | 1,035 |
0 |
0.00 |
0 |
0 |
1 |
0 |
| All others | 62,438 |
0 |
0.00 |
0 |
0 |
0 |
0 |
| TOTAL | 187,447 |
194 |
0.10% |
40 |
|||
| 285 zones in 2002, 285 zones in 2001, 286 zones in 2000 | |||||||
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.
The New Regulations
In 2002, the Company carried out monitoring for the six new parametric values set down in the new Water Supply (Water Quality) Regulations 2000. These Regulations come into force on 25 December 2003. The results are shown in the table below.
| Parameter | Total number of tests |
New standard |
Tests not meeting the new standard |
| Benzene | 692 |
1.0 µg/l |
0 |
| Bromate | 341 |
10.0 µg/l |
0 |
| 1,2 dichloroethane | 692 |
3.0 µg/l |
0 |
| Nitrite (ex-water treatment works) | 687 |
0.1 mg/l |
0 |
| Clostridium perfringens | 258 |
0/100 ml |
2 |
| Enterococci | 1,158 |
0/100 ml |
0 |
Compliance data for 2002 has also been analysed against the revised standards and the results are shown in the following table.
| Parameter | Total number or tests |
Current Standard |
Number of tests not meeting current standard |
Revised Standard |
Number of tests not meeting revised standard |
|||
| Antimony | 255 |
10.0 µg/l |
0 |
5.0 µg/l |
0 |
|||
| Arsenic | 255 |
50.0 µg/l |
0 |
10.0 µg/l |
6 |
|||
| Boron | 255 |
2.0 mg/l |
0 |
1.0 mg/l |
0 |
|||
| Copper | 291 |
3.0 mg/l |
0 |
2.0 mg/l |
0 |
|||
| Lead | 721 |
50.0 µg/l |
4 |
25.0 µg/l1 |
29 |
|||
10.0 µg/l2 |
87 |
|||||||
| Nickel | 267 |
50.0 µg/l |
0 |
20.0 µg/l |
0 |
|||
| Nitrite (at consumers' taps) | 1,542 |
0.1 mg/l |
5 |
0.5 mg/l |
0 |
|||
| PAH | 1,133 |
0.2 µg/l |
40 |
0.1 µg/l |
0 |
|||
| Tetrachloroethene | 274 |
30.0 µg/l |
|
10.0 µg/l
|
0
|
|||
| Trichloroethene | 260 |
10.0 µg/l |
Details of the new and revised standards, and the reasons for the revisions where applicable, can be found in chapter J "New Regulations and Associated Programmes of Work".
1 From 25.12.03
2 From 25.12.13
Company Audit and Inspection
The Company was inspected or audited by the Inspectorate or its appointed consultants on a number of occasions during 2002. Where relevant, report summaries are available in the 'Business and Technical' section of the Inspectorate's web site under 'Audit and Inspection'.
| Audit or Inspection | Date |
| Audit of regulatory Cryptosporidium sampling sites | Various dates throughout the year |
| Audit of regulatory Cryptosporidium samplers | January 2002 |
| Audit of laboratory analysing for Cryptosporidium | January 2002 |
| Audit of progress with regulatory programmes of work | March 2002 |
| Audit of sampling arrangements | September 2002 |
| Inspection of one water treatment works and one service reservoir | September 2002 |
| Review of distribution system undertaking | September 2002 |
| Audit of response to selected consumer complaints | October 2002 |
| Audit trails of 15 test results | November 2002 |
| Inspection of in situ lining of mains | November 2002 |
| Audit of analytical requirements for nitrate and nitrate | November 2002 |
A number of recommendations were made in respect of action required to avoid the risk of a breach of a regulatory duty. These recommendations were mainly in relation to the audit trails, in situ lining of mains, sampling arrangements and progress with regulatory programmes of work.
Incidents
The Inspectorate regarded two of the events notified during 2002 by the Company as incidents. For further details on the classification of incidents, see chapter C "Events affecting Water Quality" in Part 3.
Both of the incidents have been assessed by the Inspectorate. Each was of short duration and the Company has taken appropriate remedial action. A number of recommendations were made on notification procedures.
The Inspectorate completed the assessment of one incident which occurred in 2000.
| Nature of incident | No. of incidents |
Assessment completed |
Area affected |
Population potentially affected |
Supply of |
2 |
Yes |
Kempsey (April); |
1,530 |
discoloured water
|
Yes |
Draycott (July) |
2,860 |
Enforcement Action
No enforcement action was considered for the Company as a result of the Inspectorate activities during 2002.
Undertakings and other Improvement Programmes
Water treatment works and service reservoirs
One undertaking was due for completion during 2002. This was to install treatment at Strensham to remove lead. The programme was completed on schedule.
Two Regulation 41 programmes of work to meet the new and revised standards set down in the new Water Supply (Water Quality) Regulations 2000 were due for completion in 2002. These were to install treatment at Eyton and Oakley Farm to remove nitrate. One programme was completed on schedule. The other programme has been delayed because the preferred treatment solution was still progressing through the Regulation 25 approval process.
Nine statements of intent to reduce the risk of Cryptosporidium breaching the treatment standards were due for completion during 2002. Five of these schemes were delivered during 2002, and two others were substantially completed. The remaining schemes will be delivered in 2003.
One statement of intent for parameters other than Cryptosporidium was due for completion during 2002. This programme was completed on schedule.
Distribution
The ongoing distribution system undertaking has been progressing satisfactorily. During 2002, 430 km of mains have been renovated. The Company is required to renovate a further 583 km of mains by January 2004.
Lead
The Company has a Regulation 41 programme of work to meet the revised standard for lead set down in the new Water Supply (Water Quality) Regulations 2000, which will come into force on 25 December 2003. Progress with the delivery of the programme is monitored by the Inspectorate and has been satisfactory.
