We have received this guidance from Phiala Mehring, a local campaigner on flooding related issues, and would like to pass on her good advice to any local residents. Phiala's comments follow.
When reporting flooding it is important that you approach the correct organisation with all the relevant information:
(1) Take time and date marked photo's of the problem. It is important that these are panoramic shots as close up shoots of drains failing tend to look rather similar to one another. Please reduce the size of your photo's before emailing (otherwise they tend to clog up the recipients email account).
(2) Collect as much information as possible, for example, direction of flow, source (if you can find it), weather conditions, how widespread the problem was, etc.
(3) When phoning Thames Water, WBC or the Environment Agency you must get everyone affected to phone independently. Good neighbourly-ness in this case results in the problem only being logged once at the house of the caller i.e. if you are calling on behalf of a road, then only your property will be identified on the database as having experienced a problem.
(4) Repeat the process every time there is a problem.
Applying this process ensures that the relevant authority gets a clear picture of the problem.