From 2021:
"In a regulatory position statement issued on Tuesday, the Environment Agency introduced a waiver that would mean some companies would not have to go through the third stage in the treatment of sewage if they did not have the right chemicals."
Sewage discharge rules eased over fears of chemical shortage
Wastewater plants in England offered waiver because of impact of lorry driver crisis
www.theguardian.com
Shortage of drivers down to Brexit