It is extremely rare for drinking water to cause illness in England and Wales. The legal standards that cover drinking water quality, require water companies to ensure that water is wholesome, and that it cannot contain specified levels of certain elements or organisms, which may cause harm to human health or cause illness.
It is an offence for a water company to supply water to any premises that is unfit for human consumption. The Drinking Water Inspectorate has the power to prosecute a company, if they fail to meet this requirement.
If you believe that your drinking water is causing illness, you should consult a doctor and contact your water company in the first instance. Your water company may come to your property and take some water quality samples.
To find your local water supplier, visit the Water UK website.
The DWI is unable to comment on health matters. Any queries should be directed to a doctor or the Department of Health.