The decision follows the completion of a detailed investigation
by the Inspectorate into the outbreak of cryptosporidiosis which took
place in the north London area in March 1997. The investigation
associated with the water supplied from Clay Lane Water Treatment
Works and, in light of the judge's ruling in the Torbay case, whether
a prosecution case should be commenced. It has been decided not to
proceed with a prosecution.
A full report has been prepared which is publicly available. The
detailed recommendations are to be considered by the Expert Group on
Cryptosporidium in Water Supplies, a body set up following this
The Water Company installed in 1997 additional treatment at the
Clay Lane works to remove cryptosporidium oocysts from the water.
Michael Rouse, chief inspector of the Drinking Water Inspectorate, said:
'The inspectorate has reached this decision following a detailed
investigation into the cryptosporidium outbreak in north London, and
careful consideration of whether a successful prosecution could be
'The law as presently interpreted rules out the possibility of
proceeding in the only way which has so far been identified as
reasonably practical. I can understand that the consumers affected
will be disappointed that we are not able to pursue a prosecution.
'It is now important to study the lessons to be learnt from this
case in order to help prevent similar outbreaks from occurring.
'The source water circumstances of this case have not been
observed before and I look forward to seeing the recommendations of
the expert group on any additional safeguards that are considered
1. The inspectorate has investigated the outbreak of
cryptosporidiosis which affected a large number of people in parts of
north London in March last year and its report is available on
request. Detailed recommendations in the report will be considered
by the Expert Group on Cryptosporidium in Water Supplies. This
Expert Group was set up in response to the incident which occurred at
a water works treating ground water sources.
2. In September 1997 the inspectorate initiated a prosecution against
South West Water relating to an incident in 1995 involving an
outbreak of cryptosporidiosis in the Torbay area. At Bristol crown
court the judge, in his discretion, decreed that the Report of the
Outbreak Control Team was inadmissible. This report was part of the
evidence to be presented by the Inspectorate in support of the
prosecution of the company for allegedly supplying water unfit for
3. The inspectorate considers additional powers are necessary in
support of the necessary strong regulation of drinking water quality
in the protection of public health and a consultation document was
issued on 6 May on proposed new regulations for monitoring and
treatment of supplies of highest risk from cryptosporidium.
4. Cryptosporidiosis, which is the illness arising from exposure to
cryptosporidium, is a self limiting condition in most adults,
although unpleasant, and can last for several weeks. However,
infants, the elderly and the immuno-compromised are at greater risk
than the general population.
5. Cryptosporidium is a microscopic parasite found in man and animals
which has been recognised relatively recently as a cause of
diarrhoea. It can be spread by contact with animals and people and
by food and water. Properly operated water treatment processes are
effective in removing it but cannot entirely eliminate the risk.
6. The Drinking Water Inspectorate was set up on 2 January 1990. Its
main task is to check that water companies in England and Wales
supply wholesome water and comply with the requirements of the Water