The Drinking Water Inspectorate (DWI) said the actions taken to protect the works were adequate, but the speed taken to restore the works was not in its Incident Assessment Letter, issued today.
Mythe was overwhelmed in the floods, cutting drinking water to around 140,000 people in July and August 2007.
The Chief Inspector of Drinking Water, Professor Jeni Colbourne MBE said:
"My inspectors were generally satisfied with the actions taken by Severn Trent Water to reinstate the Mythe Water Treatment Works but the piped supply could have been restored more quickly and the delay was due to a decision to issue a health and safety notice prepared by the Gloucestershire PCT prior to the operation of valves to restore the water supply."
In the future, the Health Protection Agency (HPA) and DWI will prepare and issue joint guidance on issuing consumer warning notices.