A library of our most recent documents as well as the historic Dee Valley Water documents.
As Hafren Dyfrdwy was formed in the middle of the five year period, you will find documents here for Dee Valley Water, Severn Trent and Hafren Dyfrdwy.
Our latest 2023 reports
Read our 2023 Annual Performance Report and Methodology Statement.
Event Duration Monitor (EDM) Data
You can find our Event Duration Monitor (EDM) report here.
Each line covers a single storm overflow showing spill frequency, duration of spill and percentage of reporting period the EDM was operational.
Comments have been added to highlight key information regarding the data supplied.
The period of reporting starts from the 1st April 2020 to align with the updated Natural Resources Wales permits.