Skip to main content


Pharmaceutical residues in drinking water

Water suppliers in the UK place the highest priority and spend billions every year to provide the very best quality drinking water to their customers.

The measures UK suppliers take to treat drinking water ensure that the quality meets and exceeds the standards recommended by the World Health Organization and set by the UK's drinking water regulators.

Pharmaceutical residues may be found in very low quantities in water used as sources for drinking water. These residues get into the water sources mainly after being excreted by patients taking prescribed and non-prescribed medicines. Some residues may reach water sources after being excreted by farm animals.

The levels of these residues are thousands of times below the level associated with adverse effects in animals and hundreds of thousands of times below human therapeutic doses.

It is not practical to set formal regulatory standard for pharmaceutical residues in water (either raw water or tap water) at this stage until further research on the costs and benefits of doing so, supported by robust science, is available.

The public can also help by only disposing of unused pharmaceuticals through approved routes and not throwing them down the toilet or drains.