The UK’s rivers contain a cocktail of chemicals and stimulants including caffeine, antidepressants and painkillers from water company sewage releases, polluting freshwaters at levels which can pose a risk to aquatic life, testing has found.

Results from three days of testing in rivers by 4,531 volunteers for the environmental research group Earthwatch showed that, in addition to the chemical mix in rivers, 61% of fresh waters in the UK were in a poor state because of high levels of the nutrients phosphate and nitrate, the source of which is sewage effluent and agricultural runoff. England had the worst level of poor water quality in rivers, with 67% of freshwater samples showing high levels of nitrate and phosphate.

“Our rivers have been historically stressed by farming and are being pushed to the brink by outdated and inadequate sewage treatment works,” Earthwatch said.