What it is
Aluminium is the most common metal in the earth's crust. It dissolves into acidic water from soils and rocks, and it is also used as a coagulant in some water treatment.
Where it comes from
In private supplies aluminium comes mainly from acidic water passing through peaty or granitic ground. In treated water it can come from coagulant carried over when a treatment stage is not working well.
Why it matters
The UK guideline is set at a level that prevents discolouration and deposits. Aluminium at drinking-water levels is not considered a significant health risk by UK or WHO guidance, although it is kept under review. Very high levels can make water cloudy and leave white deposits.
What can be done about it
Where the cause is acidic water, correcting the pH reduces the aluminium it carries. Fine particulate aluminium is removed by filtration; dissolved aluminium by reverse osmosis if needed.
Information last reviewed 5 October 2026 by Pozzani Pure Water.