UK water firms face chemical distribution supply chain issues
The decision comes in response to problems in the chemical supply chain caused by the lorry driver shortage that has hit other sectors like the food supply chain.
Water UK said there was no shortage of chemicals, but just distribution problems.
The Environment Agency issued a regulatory statement authorising "a temporary reduction in the dosage used to treat waste water".
The Chemical Business Association (CBA), which represents chemical businesses within the supply chain, had expressed concern that its members were struggling to get chemicals into the logistics network and to water companies because of a shortage of HGV drivers.
"Our member companies have been reporting ever increasing difficulties in sourcing and maintaining deliveries into the chemical supply chain, all of which we have been highlighting to government, said Tim Doggett, chief executive of the CBA.
"Inevitably these issues are now beginning to impact the our water supply. As such we're now calling on government for urgent and increased action to help tackle these issues."
A spokesperson for Water UK said: "We are currently experiencing some disruption to the supply in England of ferric sulphate, a chemical used at some drinking and waste water treatment sites.
"This will not affect the supply of drinking water. As a precaution, however, we are monitoring the situation due to the use of ferric sulphate in some waste treatment works.
"We are working closely with government and our chemical suppliers to ensure disruption is minimised.