Thames Water "Hydraulic Overload" sewer flooding

Quiet_penguin

I'm not quite sure where to post this but I'm hoping somebody may have some expertise or insight to offer. 

Our small terrace row has a shared sewer line which runs to the main sewer line on our road - both owned by Thames Water.  In times of heavy rain, there is a history of our passage way flooding and the drains backing up so that foul water stands around 20cm deep and flows down our passage way, into our poor neighbour's home (they have been flooded out by foul water on 3 occasions since 2021) and into an open water stream which runs along the village green.   The water flares up for about 30 mins, does its damage and then dies down.  We have had a series of Lanes Engineers acting for Thames Water who come out and say it's 'hydraulic overload' and there's nothing they can do.   

Our local MP intervened last year and Thames Water eventually conceded they had a problem (only after a volcano of sewage also erupted on the green one morning)  They emailed us to say they had made "patch repairs" to the main sewage line.  All was ok until this weekend when the same thing happened again.  Again, Lanes Engineers have visited (5 times) to tell us a) they can't check the main sewer line because they don't have the right equipment and a Network Engineer will be required to do that b) Thames Water won't do anything because Hyrdraulic Overload is considered an act of god?!  We cannot get a Network Engineer to come out at all - we are promised call backs, appointments and many other things but nothing ever happens.  Last night it happened again - 3 days after the previous incident - entering my neighbours property and meaning all of us had to be out with buckets bailing out the passage way full of sewage water at 11pm at night.   Again a Lanes Engineer has visited (after 28 mins on hold to their emergency number) and a 7 hour wait overnight - surprise surprise - he tells us only a Network Engineer can help.  Thanks to the interventions again of our local MP we do have a Case Worker at Thames Water to whom I will send all the videos I took last night of sewage flowing into open water...but I am afraid I am losing faith that Thames Water will ever do anything and thinking perhaps we, as a group of neighbours, need to do something and put in some kind of private drainage solution for rain water that will help.  I fear that the main sewage line is ultimately the culprit and anything we do will be insufficient but I wondered if anybody had any advice on practical solutions or what our rights are here? 

Jonboy_1984

Do your rainwater gutters feed into the sewer, or are they a newer installation that goes to soak-aways under your gardens?

If they are older ones that feed into sewers then either getting them converted to soakaways or fitting waterbutts* to each downpipe would reduce the overload.

*you would need to half empty them if they were full and more rain is forecast

Section62

Quiet_penguin said:

...b) Thames Water won't do anything because Hyrdraulic Overload is considered an act of god?! ....

Nonsense.

As TW have carried out some repairs on the main sewer, my guess would be this is defective and at times of rainfall some kind of blockage or restriction is causing the flow to back up and exit via the lowest effective point.  That may well be the shared sewer serving your properties.

In other words, the flooding ins't necessarily caused by the water entering your sewer from the gutters and drains etc, but rather from water in the main pipe finding its way back up and exiting onto your property.  In the first instance I don't think doing anything about your own rainwater will make much difference.

Potentially one way of resolving a situation like this is to fit a flap-valve on your shared sewer so the flow cannot go from the main sewer back into your pipes.  Generally drainage engineers will resist fitting these to foul or combined sewers because 'stuff' can get caught in them and cause blockages (which in this case TW would be responsibile for the consequences of).

This is a case where traditionally the solution would have been one of those evil 'overflows' we see so much about in the news.  An overflow pipe would be constructed from the foul sewer into the stream, so when conditions meant the main foul sewer was under 'Hydraulic Overload', the excess flow would be diverted directly to the stream, rather than ending up in the stream via people's houses and gardens. The logic being that if the sewage is going to end up in the stream anyway, then better it gets thee without causing inconvenience and damage to people and property.

TW cannot use an "act of god" excuse over this. A one-off event which exceeds the design capacity of the sewer is one thing, but repeated failures points to an issue with the sewer (collapse or blockage).  They have a responsibility to ensure that sewage which enters their system is properly managed and disposed of.  If it comes out of the pipes into your properties then it simply isn't good enough for them to blame god.

Speak to your TW case worker and let them know you won't be fobbed of with "act of god" or "climate change" excuses.  They need to get their network engineer investigating why the main sewer - out of the blue - has started causing this problem, and if they have carried out "patch repairs" then why didn't this resolve the issue.

I would also make contact with the Environment Agency - they aren't as effective as they used to be, but complaining to them about what amount to sewage spills might eventually get someone to take notice and do something about it.