The Drinking Water Inspectorate (DWI), an independent body, is one of the three water industry regulators. It checks water companies in England and Wales supply wholesome water and comply with the water supply (water quality) regulations 1991.

DWI marked its tenth anniversary this year and it is appropriate to consider the improvements since the introduction of drinking water quality regulations;

  • DWI initiates enforcement action when there is a breach of standards. More than 2,800 enforcement actions have been taken over the last ten years. As a result, quality has improved continuously from 1992 to 1999,
  • the latest figures revealed that of approximately 2.8M tests performed in 1999, 99.82% met the required standards. The number of failed tests is now just one-tenth of the 1992 total,
  • pesticides have been all but eliminated from drinking water. In 1999, of the 641,000 tests carried out, 99.99% met the standard.

In addition to its inspection and enforcement functions, DWI investigates incidents and can initiate a prosecution if water unfit for human consumption has been supplied. However, prosecutions, compared with enforcement action, are relatively rare, there having been just 24 in the ten-year period. DWI also supports the committee on chemicals and materials.

A current and important activity is the implementation of the new Cryptosporidium regulations. These regulations, which came into force on 1 April 2000, have introduced a treatment standard of less than one Cryptosporidium oocyst per ten litres water, with continuous sampling to check treatment works are functioning effectively. Exceedance of the standard is a criminal offence but with a due diligence defence provision.

Early results are showing, as expected, that although the majority of daily samples contain no oocysts, low levels are present on occasions. During April and May, 134 monitoring sites came on stream and 6,336 samples were taken. In all 5,649 (89%) samples contained no Cryptosporidium oocysts. The remaining samples, which came from 60% of sites, contained some oocysts, generally at very low levels. There were no reported cases of illness in the community associated with any of these detections of oocysts.

We lead the world in protection against Cryptosporidium. This is the first country to introduce specific regulations and have continuous sampling in place. Through the enhanced monitoring, water companies are able to optimise the operation of their treatment plants and take early action if there are indications of problems. This allows public health risks to be kept to a minimum.

The continuing improvement in drinking water quality is excellent news for consumers. However, we cannot be complacent. In this new era of competition and possible re-structuring of water companies, DWI will remain vigilant in protecting public health and enforcing standards.

Michael Rouse, chief inspector, Drinking Water Inspectorate

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