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Water companies must take on board the lessons learned during ...
Water companies must take on board the lessons learned during

drinking water incidents, if consumers are to be protected warned the

chief inspector of the Drinking Water Inspectorate (DWI). He

commented as the DWI sent out its latest findings to the water


Water companies are obliged by law to notify the secretaries of

state for the environment and Wales if any occurrence or event might

affect the water supply such that there could be a significant health

risk to consumers. The DWI investigates all such incidents, and

takes further action to enforce standards where appropriate.

The DWI found that between January 1990 and 1996:

- there was a reduction in the number of incidents relating to

treated water reservoirs following enforcement action taken in

the early years by the DWI;

- action by the DWI may have caused a reduction in the number of

disinfection failures in recent years;

- there was an increase in the number of occasions where

consumers received discoloured ('dirty') water because of

incidents in the distribution system;

- there were continuing improvements in the system of

notifications from water companies to the DWI; and also that:

- the most common single cause of incidents in recent years was

operational deficiencies, many of which were associated with the

failure of companies to follow their own procedures.

The findings were included in one of a series of Information Letters

issued by the DWI to the water companies. The aim of these letters

is to inform the water companies of matters that DWI, as Guardians of

Drinking Water Quality, considers important. This particular

Information Letter informs water companies of lessons to be learned

arising from the Inspectorate's investigation of particular


A recent Information Letter has addressed the concerns of the DWI

about the increasing number of incidents involving 'dirty' water. In

1996, 42.1 per cent of all notified incidents were of dirty water

associated with the distribution system (e.g. because of burst

mains). This compares with 25.3 per cent of incidents in 1995.

The chief inspector of the DWI, Michael Rouse said that he aims to

reduce the number and severity of incidents in the future.


The Drinking Water Inspectorate (DWI) is a team of professionals with

wide-ranging experience and expert knowledge on all aspects of water

supply. The DWI is advised on health matters by the government's

chief medical officer.

The DWI :

- carries out technical audits of water companies;

- advises the Secretary of State on the steps required to

enforce obligations under the relevant legislation;

-investigates incidents which affect drinking water quality


-advises the Secretary of State on the prosecution of

water companies if water has been supplied which is unfit for

human consumption;

-provides technical and scientific advice to Ministers and

officials of the Department of the Environment, Transport and

the Regions and Welsh Office on drinking water policy issues;

-identifies and assesses new issues or hazards relating to

drinking water quality and initiates research as required;

-assesses and responds to consumer complaints when local

procedures have been exhausted; and

-assesses chemicals and materials used in the provision of water


DWI Information Letters are not intended as a good code of practice,

but rather inform companies of the matters that the DWI, as Guardians

of Drinking Water Quality, considers important. Information Letters

are published at intervals throughout the year.

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