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L'înformâtion et les sèrvices publyis pouor I'Île dé Jèrri

Private water supplies: pollution and testing

​​​​​​​​I think my private water supply is polluted - what do I do?

If you think your water is polluted, for instance it is discoloured ​or smelling please do not drink it and contact the States Official Analyst to have your water tested. Please note there is a charge for this service.

2015 testing costs​

  • £60.90 for chemical analysis
  • £46.20 for microbiological analysis
  • £95.55 for both the above analyses
  • £13.65 for nitrate only

All above charges are inclusive of GST.

Borehole and well water testing

Bores and, especially, wells are subject to possible pollution from pesticides, harmful bacteria and microscopic parasites such as Cryptosporidia and Giardia and they may also be high in nitrates. It is important to realise that water analysis is also only a snapshot in time (eg 1 sample in 1 year) and does not necessarily guarantee a safe supply and nitrates are likely to vary over time.

If you are pregnant and use a borehole or well for your drinking water, you may wish to have your water tested by a reputable water treatment company or the States Official Analyst.

Treating polluted water

Due to the uncertainty over the safety of private water supplies you may wish to treat the water (eg chlorine or Ultra violet (UV) light treatment) or use bottled water or connect to mains water if this is practical. Advice on treatment can be obtained from the Health Protection Department or a reputable water treatment engineer. If you decide to use a water filter, ensure it is clear in what it is designed to do. Many filters will not remove nitrates.

If you are on mains water and you want your water testing you will need to contact Jersey Water.

Why should I connect to mains water?

It is a major concern that not only do many households rely on private water supplies that are most vulnerable to pollution from agro-chemicals (eg herbicides, pesticides and insecticides) and bacterial run-off from fields, but in some cases they positively choose to do so. We recommend to those on borehole or well water to connect to mains water to prevent possible contamination.

The acceptability of nitrate concentrations in drinking water is measured against the standard set out in a European Council Directive, with 50 milligrams per litre (mg/l) being the recommended maximum concentration.

The action you may need to take will depend on whether your water is from the mains supply or from a borehole or well etc.

Nitrate concentrations - the health risks

If the nitrate concentration in mains water exceeds 50 mg/l and is between 50 - 100 mg/l consumers are of a slight increased risk to the health of certain groups, such as babies under 6 months of age who are at risk of developing Methaemoglobinaemia (' blue baby' disease where the baby is starved of oxygen). There has, however, not been a case of Methaemoglobinaemia in Jersey in the last 20 years.

If levels do exceed 50 mg/l you should use bottled water. The bottled water should also be low in nitrates. Bottled water should be still and not sparkling and also be low in sodium (ie salt under 100- mg/l).

Generally speaking, mains water is fine for babies' bottles following boiling, however you may personally wish to use bottled water.

​​Jersey Water website

Download Dr Grainger's Report: Vunerability of private drinking water from bores and wells 1995 (Jersey) (size 12kb)

Download Water Safety booklet (size 493kb)

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