UK Legal Limit
0.005 mg/L
WHO Guideline
0.003 mg/L
EU Standard
0.005 mg/L
Primary Sources
Galvanised pipes, industry
Cadmium in UK drinking water is regulated at 0.005 mg/L. The WHO guideline is 0.003 mg/L and the EU standard is 0.005 mg/L. Cadmium is a Group 1 carcinogen that accumulates in the kidneys over a lifetime. It can leach from galvanised pipes and industrial sources.
Cadmium is highly toxic to the kidneys, where it accumulates over a lifetime and can cause irreversible damage to the renal tubules. Long-term exposure is associated with kidney disease, bone demineralisation (leading to osteoporosis and fractures), and increased cancer risk — particularly lung and kidney cancer. The IARC classifies cadmium as a Group 1 carcinogen (carcinogenic to humans). Even at low levels, chronic exposure can impair calcium metabolism and weaken bones, particularly in post-menopausal women.
Cadmium in UK drinking water can leach from galvanised steel pipes and fittings, cadmium-containing solders, and some older plumbing components. Industrial sources include zinc smelting, battery manufacturing, electroplating, and waste incineration, which can contaminate surface water and groundwater. Agricultural use of phosphate fertilisers (which contain trace cadmium) and sewage sludge spreading can also contribute to cadmium in source water over time.
| Jurisdiction | Limit / Guideline | Notes |
|---|---|---|
| UK (DWI) | 0.005 mg/L | Regulated under the Water Supply (Water Quality) Regulations 2016 |
| WHO | 0.003 mg/L | World Health Organization Guidelines for Drinking-water Quality |
| EU | 0.005 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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