Guidance: Water companies: control of chemicals used for dosing at waste water treatment works

This guide is for water companies who want to carry out chemical dosing at waste water treatment works (WWTW).

The Environment Agency regulates WWTW by assessing the quality of the waste water they discharge against set compliance limits. This guide explains how we set limits and control the substances used for chemical dosing.

This guide covers dosing:

• with iron and aluminium salts
• with polyelectrolytes
• for pH adjustment