UK Legal Limit
0.2 mg/L
WHO Guideline
0.2 mg/L
EU Standard
0.2 mg/L
Primary Sources
Water treatment process
Aluminium in UK drinking water is regulated at 0.2 mg/L. The WHO guideline is 0.2 mg/L and the EU standard is 0.2 mg/L. Most aluminium in UK tap water comes from aluminium sulphate added during treatment. A debated link to Alzheimer's disease remains inconclusive.
The health effects of aluminium in drinking water have been debated for decades, with particular attention on a possible link to Alzheimer's disease. Some epidemiological studies have found an association between elevated aluminium in drinking water and increased risk of cognitive decline, though the evidence remains inconclusive and contested. Aluminium is not classified as a carcinogen. At very high levels, aluminium can cause gastrointestinal irritation, and it may accumulate in bone tissue in people with impaired kidney function.
The main source of aluminium in UK drinking water is the aluminium sulphate (alum) used as a coagulant in water treatment. When treatment works are operating correctly, most aluminium is removed along with the particles it binds to. However, operational upsets, rapid changes in raw water quality (such as after storms), and suboptimal pH control can lead to elevated residual aluminium in treated water. Natural aluminium from soil and rock dissolution also contributes to levels in raw water sources.
| Jurisdiction | Limit / Guideline | Notes |
|---|---|---|
| UK (DWI) | 0.2 mg/L | Regulated under the Water Supply (Water Quality) Regulations 2016 |
| WHO | 0.2 mg/L | World Health Organization Guidelines for Drinking-water Quality |
| EU | 0.2 mg/L | EU Drinking Water Directive (2020/2184). The UK no longer automatically mirrors EU standards post-Brexit. |
Reverse osmosis
A membrane filtration process that removes up to 99% of contaminants by forcing water through a semi-permeable membrane under pressure. Highly effective but produces some wastewater.
Distillation
Water is boiled and the steam condensed, leaving most contaminants behind. Highly effective but slow and energy-intensive — typically used in countertop units.
Ion exchange
Replaces unwanted ions (such as nitrate or lead) with harmless ones using resin beads. Effective and widely used in both whole-house and point-of-use systems.
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