What it is
Mercury is a heavy metal that is toxic in all its forms. It is almost never found in UK drinking water at measurable levels, and it is offered as an add-on for supplies where there is a reason to check.
Where it comes from
Mercury reaches water from industrial discharge, old mine workings, contaminated land and, in small amounts, from atmospheric deposition. Some old dental and laboratory waste is a local source.
Why it matters
Mercury accumulates in the body and affects the kidneys and nervous system. The guideline is set low to keep lifetime intake well within safe limits. A result over it would be unusual and would be followed up with the laboratory and a resample before anything else.
What can be done about it
If confirmed, the engineer looks for the source. Reverse osmosis and specialist adsorption media remove mercury from water; a point-of-use unit at the kitchen tap protects drinking water while the source is addressed.
Information last reviewed 5 October 2026 by Pozzani Pure Water.