Exclusive: Firms made more than £340m last year from processing industrial and commercial wastewater at sewage works that are unable to remove many chemical pollutants

Water companies in the UK made more than £340m in revenue last year by pouring billions of litres of industrial and commercial wastewater into sewage treatment works that experts say are not designed to remove most chemicals, leaving pollutants to pass into rivers, seas and farmland.

Water companies are required by law to take industrial wastewater and issue permits called “trade-effluent consents” that allow businesses to send it to sewage works, though water companies can refuse applications.