H. The Cryptosporidium Regulations
Following outbreaks of cryptosporidiosis in 1995 and 1997, additional regulatory measures to protect public health were introduced.
The Regulations
The Water Supply (Water Quality) (Amendment) Regulations 1999 came into force on 30 June 1999. In England these have been incorporated into the new Water Supply (Water Quality) Regulations 2000.
They set a treatment standard of an average of less than one oocyst in 10 litres of water supplied from a treatment works.
The Cryptosporidium Regulations specified continuous sampling of not less than 40 litres per hour of treated water going into supply. The Regulations require physical removal of oocysts and the treatment standard does not take into account different species of Cryptosporidium, nor whether any oocysts detected are viable, i.e. alive and potentially able to cause infection, or not.
Implementing the Regulations
Water companies were required to carry out a risk assessment for each of their water treatment works by 30 September 1999.
The assessments established whether there was a significant risk of breaching the standard.
Guidance on risk assessment was issued with the Regulations and has been posted on the Inspectorate’s web site.
The significant risk classification does not imply a breach of the standard but rather that there is potential for a significant number of Cryptosporidium oocysts to be present at times in the treated water.
For works identified as at significant risk, water companies must treat the water to ensure that the standard is met. They must also demonstrate compliance by continuously monitoring the water leaving the works and reporting the results of the daily analysis.
332 out of the 1481 treatment works in England and Wales were identified as being at significant risk. Of the 332 at significant risk, 158 were works treating surface water and 174 were groundwater abstractions.
Regulatory monitoring is required to demonstrate that the treatment standard is being met. Monitoring at the highest risk sites began on 1 April 2000 and monitoring has commenced at other works, in accordance with a programme agreed with the Inspectorate.
As an alternative to continuous monitoring, a water utility may install treatment plant capable of continuously removing or retaining particles greater than one-micron diameter.
Improvement Programmes
Where such water treatment works have been identified as at significant risk under the Regulations and current treatment is considered to be inadequate, the Inspectorate has agreed an improvement programme with the water company for appropriate treatment to be installed or in some cases for the source to be abandoned or changed.
Until treatment is installed or other action taken, water companies are encouraged to monitor the treated water continuously and report these operational results to the Inspectorate. However, these data are not included in the regulatory results reported below.
Analysis of Samples
The protocol issued with the Regulations lays down the requirements for the laboratory facilities and analytical method that must be used for compliance testing.
Analysis can only be carried out at laboratories approved by the Inspectorate and these are subject to unannounced inspections. Samples must be analysed within three days of being taken, unless there has been a significant increase in turbidity of the water being sampled or some other indication that the number of Cryptosporidium oocysts in the water may have increased. In this case, analysis must be completed within a day of the sample being taken.
Strict rules are laid down for all aspects of sampling and analysis to permit the use of the analytical results as evidence in a Court of Law. Full details of all approved procedures have been posted on the Inspectorate’s web site.
All regulatory sampling points and analytical laboratories were audited at least once during the year 2000.
Sample Results
Regulatory monitoring results are available for the first nine months operation of the Regulations, from 1 April 2000 to 31 December 2000.
During this period 36,916 samples have been taken from 188 sites. Oocysts have been detected in 2,755 (7.46%) samples taken from 108 (57.4%) sites.
The great majority of detections, 91%, have been in the range 0.01 - 0.10 oocysts per 10 litres. Seven results from two sites have contravened the standard, the highest count was 4.91 oocyst per 10 litres.
Outbreaks of cryptosporidiosis have not been associated with these breaches and the Inspectorate is unaware of any increase in illness in areas supplied by those sites being monitored under the Regulations.
It is too early to draw firm conclusions from the results because not all sites have yet come on stream for continuous monitoring and others have yet to complete a full year’s seasonal conditions.
However, a lot of very useful data have been collected already and early indications are that treated drinking water is not a major source of exposure of the population to Cryptosporidium oocysts.
[ Previous ] [ Contents ] [ Next ]
| A - Z Index | Business and Technical | Consumer Information | Contacting us |
| DWI Home Page | News | Product Approval | Search our site | Wales |
Drinking Water Inspectorate,
Floor 2/A1, Ashdown House, 123 Victoria Street, London, SW1E 6DE
Telephone : 020 7944 5956 - Facsimile : 020 7944 5969
E-mail: dwi_enquiries@detr.gov.uk
Published 11 July 2001
Return to Publications and Reports Index
Return to Drinking Water Inspectorate Home Page
Department for Environment, Food & Rural Affairs (DEFRA)Home Page
The National Assembly for Wales / Cynulliad Cenedlaethol Cymru Home Page
Web site terms
© Crown copyright 2001