UK Legal Limit
0.05 mg/L (total chromium)
WHO Guideline
0.05 mg/L
EU Standard
0.025 mg/L (from 2036)
Primary Sources
Chrome plating, tanning
Chromium in UK drinking water is regulated at 0.05 mg/L (total chromium). The WHO guideline is 0.05 mg/L and the EU standard is 0.025 mg/L (from 2036). Hexavalent chromium is carcinogenic. The EU will tighten its standard to 0.025 mg/L from 2036 — half the current UK limit.
Hexavalent chromium (Cr-VI) is classified as a Group 1 carcinogen by the IARC when inhaled, and ingestion through drinking water has been linked to stomach and intestinal cancer in animal studies and some human epidemiological research. Chronic exposure to Cr-VI in drinking water may also cause liver and kidney damage, reproductive harm, and allergic skin reactions. Trivalent chromium (Cr-III) is far less toxic and is actually an essential trace nutrient involved in glucose metabolism. The challenge for regulators is that standard testing measures total chromium without distinguishing the toxic hexavalent form.
Chromium enters UK water sources from both natural and industrial origins. Natural weathering of chromium-containing rocks contributes low background levels. Industrial sources are more significant and include chrome plating facilities, leather tanning operations, textile dyeing, stainless steel manufacturing, and wood preservation using chromated copper arsenate. Legacy contamination from historical industrial sites can persist in groundwater for decades. Some older cooling water systems also used chromium-based corrosion inhibitors.
| Jurisdiction | Limit / Guideline | Notes |
|---|---|---|
| UK (DWI) | 0.05 mg/L (total chromium) | Regulated under the Water Supply (Water Quality) Regulations 2016 |
| WHO | 0.05 mg/L | World Health Organization Guidelines for Drinking-water Quality |
| EU | 0.025 mg/L (from 2036) | 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.
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.
Activated carbon
Porous carbon material (from charcoal or coconut shell) that adsorbs contaminants as water passes through. Best for organic compounds and some heavy metals.
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