Press Release

Drinking Water Inspectorate
55 Whitehall
London
SW1A 2EY

Tel: 0207 270 3370
E-mail: dwi.enquiries@defra.gsi.gov.uk

5 November 2008

Inspectorate concludes Pitsford incident investigation

Today the Drinking Water Inspectorate published its independent assessment of the incident involved the issuing of a boil water notice to some 258,000 consumers living in the Northampton and Daventry area in June 2008.

The Inspectorate has concluded that the cause of the incident was a failure of basic water supply hygiene arrangements at Pitsford works operated by Anglian Water.  This oversight by the company allowed a small rabbit to gain access to a wash water tank. The consequences of this were that the entire drinking water distribution system became contaminated by a strain of the Cryptosporidium parasite which infects rabbits. Prompt action by the company ensured an appropriate and effective multi agency  health protection response.  Although a large number of consumers were inconvenienced by the need to boil their drinking water,  this precautionary advice undoubtedly played a vital role in keeping the adverse consequences for human health to a minimum.          

In concluding the investigation, Deputy Chief Inspector Marcus Rink said :-

“ my inspector is critical of this failure of basic water supply hygiene arrangements  however his assessment rightly highlights how it was Anglian Water’s own robust monitoring procedures which raised the alarm  and secured a quick and effective multi agency response” 

The enhanced health surveillance put in place following the alert subsequently found that 22 people contracted Cryptosporidiosis due to the same genotype of the Cryptosporidium parasite found in the rabbit and water samples, prior to this incident only a single case of human infection with this strain had been recorded anywhere in the world.

The Inspectorate has acted to close gaps in scientific knowledge revealed by this incident .  It has commissioned studies into the rabbit genotype of Cryptosporidium led by the UK Cryptosporidium Reference Unit , NPHS , and funded by DEFRA. 

Commenting on this work Professor Jeni Colbourne MBE,  Chief Inspector of Drinking Water,  said   “ Consumers can be assured that action has been taken to learn from this incident “.

In a stark message to the water industry she said “ my inspectors consistently reinforce  the need for close attention to be paid at all times to water supply hygiene arrangements; this incident shows how anything less than constant vigilance is unacceptable”.                                                 

Notes to Editors

1. The Drinking Water Inspectorate was set up in January 1990. Its main task is to check that water companies in England and Wales supply wholesome drinking water and in doing so comply with the requirements of the Water Supply (Water Quality) 2000  Ammendment Regulations 2007.  DWI takes enforcement action to require water companies to make water quality improvements for any non trivial breach of the regulations.  DWI also has the powers to initiate proceedings for the offences in the Regulations which relate to water treatment (Regulation 26) risk assessment notices (Regulation 28) and use of approved materials (Regulation 31). Section 70 of the Water Industry Act 1991 created the offence of supplying water which is unfit for human consumption. DWI investigates all drinking water quality incidents and since the Water Act 2003 can initiate proceedings in the name of the Chief Inspector of Drinking Water. Prosecutions under the Act or the Regulations are taken forward where there is reliable evidence that an offence has been committed, where the company does not have a defence that it took all reasonable steps and exercised all due diligence, and when such a prosecution is regarded as being in the public interest.
   
   
2. When investigating any incident, the Inspectors follow a process of careful information gathering, collation and analysis. The Chief Inspector will then make a decision on whether there is a case to be answered.
   
   
3. Cryptosporidium is a parasite (not a bacteria), the disease it causes in humans in called Cryptosporidiosis.
   
   
4. The Inspectorate was notified by Anglian Water of the presence of Cryptosporidium in treated water from the Pitsford Water treatment Works on the 25th June 2008. An incident management team was formed and the decision was made to implement a Boil Water Notice for the affected area (258,000 population).
   
   The boil water notice remained in place until 4th July 2008. Anglian water took a twin track approach to protecting public health by fitting Ultra Violet (UV) treatment at the treatment work to inactivate the parasite and by instigating a full investigation to identify and remove the cause. 
   
   This investigation revealed that a small rabbit had entered a tank storing water used in the treatment process to backwash filters. The rabbit was the source of Cryptosporidium oocycts which then found their way into the treated water.
   
   
5. The Drinking Water inspectorate independently investigated the circumstances of the incident and agreed that the sole credible explanation for the presence of the rabbit was that it entered the tank either through a damaged hatch cover or alternatively through one of two ventilators on the tank roof which were missing meshes designed to prevent the entry of insects and small animals to the tank.
   
   
6. The Incident Assessment Letter will be made available after 14.00 hrs on Wednesday 5th November. For a copy of the Incident Assessment Letter containing details of the incident and full recommendations, please contact the Drinking Water Inspectorate on 0207 270 3370

Issued by COI on behalf of the Drinking Water Inspectorate

Media contacts :

DWI – 0207 270 3370

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