Question to the Department for Environment, Food and Rural Affairs:

To ask the Secretary of State for Environment, Food and Rural Affairs, whether his Department has made an assessment of the potential merits of introducing of mandatory quaternary water treatment of wastewater.

Defra currently has no plans to introduce and make quaternary treatment mandatory for domestic wastewater treatment. Where it is deemed necessary as an additional wastewater treatment process, costs and benefits will be assessed, and stakeholder consultations will be performed through the normal routes.