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Information and public services for the Island of Jersey

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

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Private water supplies: pollution and testing

What to do if you think your private water supply is polluted

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

2024 testing costs​ (inclusive of GST)

  • £74.03 for chemical analysis
  • £57.23 for microbiological analysis
  • £118.65 for both the above analyses

Borehole and well water testing

Boreholes, and especially wells, are subject to possible pollution from pesticides, chemicals, 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 (for example one sample in one year) and does not necessarily guarantee a safe supply and nitrates are likely to vary over time. If testing your water an 11 or 13 month cycle is recommended to, over time, get an understanding of your water quality across a year.

If you are pregnant, are breastfeeding or have young children and use a borehole or well for your drinking water, you may wish to have your water tested by the States Official Analyst or private water supplier.

Private Water Supplies - Water Safety

Treating polluted water

Due to the uncertainty over the safety of private water supplies, you may wish to treat the water with treatments such as:

  • sediment filters
  • chlorine
  • ultra violet (UV) light treatment
  • reverse osmosis

Alternatively you could use bottled water or connect to mains water. You can get advice on treatment from Environment and Consumer Protection or a reputable water treatment engineer. If you decide to use a water filter, check what it is designed to do as 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.

Reasons to connect to mains water

It is a concern that many households rely on private water supplies that are most vulnerable to pollution from chemicals used on the land, for example:

  • herbicides
  • pesticides
  • insecticides
  • domestic chemicals
  • bacterial run-off from fields or septic tanks

We recommend to those on boreholes 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, a borehole or well etc.

Possible pollutants and public advice


Per and polyfluoroalkyl substances (PFAS) are a group of man made chemicals. They are of particular interest in Jersey because of their presence in some borehole water sources.

Find more information on PFAS in Jersey.

Nitrate concentrations

If the nitrate concentration in your drinking water exceeds 50mg/l and is between 50 to 100mg/l, there could be an increased health risk to 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 in Jersey in the last 20 years.

If levels do exceed 50mg/l you should use bottled water. The bottled water should be:

  • low in nitrates
  • still and not sparkling
  • low in sodium (for instance, salt under 100mg/l)

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

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