It would interesting to know what your superficial ground is made up of. (Clay, sand, gravel etc) Soakaways are not normally dug in cohesive soil. All you are creating is a deep pond. I doubt its a water main - possible, but I think unlikely. Has your pressure from the tap fallen? I suspect that the removal of the vegetation may have played a part - its possible there was historic land drains installed (and its surprising how much shrubs soak up water). The fact that the "builders" layed the turf is somewhat worrying. The bulding work I suspect is also a major cause - namely poorly designed or installed drainage or damage to existing drains. Also the building may have changed the direction of surface water run off (or indeed, ground water) in that any water that used to flood next door is now directed into yours. Other possibilities are that the building work has disturbed perched water or they released artisian water during excavtion - very unlikely though.
Whatever the cause it all points to the the new extension. Contacting a legal professional is a good start. I'm afraid I don't really subscribe to the "would you mind awfully" approach, especially with ignorant neighbours. It's stressful (and even more annoying becasue it was probably avoidable) but a solictors letter is often the only means by which people like this will take note. Best wishes to your parents & I truly wish you luck.
These are links to websites that may not necessarily help but you may find give you more info:
Highest probability from what you've said is a soakaway problem. Either they've put in a new one and it is badly built and sited, so it's discharging onto your parents' garden. Or the work has caused damage or blocked an old one. That would be my prime candidate. Especially if there was some heavy rain while the work was going on, silt and mud washing into the soakaway may have blocked it so it's no longer soaking away.
I would contact Building Control as a priority as they will have overseen the work and should have checked that appropriate measures were taken to deal with the rainwater runoff from the new work. Builders have used taken advantage of Covid restrictions to bodge their way out of some work hoping that no one will visit site to check on it. Be insistant that they confirm in writing what was done and that they have fully inspected it.
I'm having similar problems here with neighbours' sheds and hard landscaping directing water through my garden. Luckily it's doing very little harm at the moment but it seems to be a common picture that additional rainfall is overloading drainage infrastructure everywhere.
If you can keep your head, while those around you are losing theirs, you may not have grasped the seriousness of the situation.
I appreciate over 2 years has elapsed but was a satisfactory resolution obtained to this problem? I ask because I appear to have exactly the same issue: my nextdoor neighbour is building an extension part of which involved renovating his very large rear garden (in which he experienced significant flooding), cleared out all existing bushes etc, and deposited 110 tonnes of new subsoil raising the level (as well as angle) of his garden by some 30cm overall. My rather small rear garden bordering his property is now flooding for the first time in the 36 years that we've lived here, such that the bottom of my garden is permanently underwater. I'd be very interested to know how this issue progressed and as to the outcome, was a satisfactory resolution reached and if so, how.....? Thanks
I just told my neighbours about it. They were very amenable , realised they had caused the problem and sorted it. Firstly I would talk to them, they may not realise they have caused a problem. If they adopt the "its not my problem" attitude, you have the choice of going down the legal route (expensive), or putting in land drains or a pond or a soakaway on your side ( expensive)
Many thanks for your feedback and advice. I raised my concerns with my neighbour when the flooding first started but the impression I had was he didn't want to know about it. He did say he'd speak with his builder but I've had nothing back from him. The family's not living in the property so I've emailed him - I'll wait and see what response is forthcoming. I've also messaged Beebop direct.
Many years ago in a garden where I worked a builder drained a garden into a field next door. Illegal but it obviously happens with the thought hope I don't get caught. @Stewart.H.Marr I hope this problem can soon be resolved. @Beebop164 My Best Wishes to your Family I know as you get older things worry you more in this situation with good reason.
I have worked as a Gardener for 24 years. My latest garden is a new build garden on heavy clay.
Posts
Soakaways are not normally dug in cohesive soil. All you are creating is a deep pond.
I doubt its a water main - possible, but I think unlikely. Has your pressure from the tap fallen?
I suspect that the removal of the vegetation may have played a part - its possible there was historic land drains installed (and its surprising how much shrubs soak up water). The fact that the "builders" layed the turf is somewhat worrying.
The bulding work I suspect is also a major cause - namely poorly designed or installed drainage or damage to existing drains. Also the building may have changed the direction of surface water run off (or indeed, ground water) in that any water that used to flood next door is now directed into yours.
Other possibilities are that the building work has disturbed perched water or they released artisian water during excavtion - very unlikely though.
Whatever the cause it all points to the the new extension. Contacting a legal professional is a good start. I'm afraid I don't really subscribe to the "would you mind awfully" approach, especially with ignorant neighbours. It's stressful (and even more annoying becasue it was probably avoidable) but a solictors letter is often the only means by which people like this will take note. Best wishes to your parents & I truly wish you luck.
These are links to websites that may not necessarily help but you may find give you more info:
Learn more about flood risk - GOV.UK (flood-warning-information.service.gov.uk)
Geology of Britain viewer | British Geological Survey (BGS)
I'd be very interested to know how this issue progressed and as to the outcome, was a satisfactory resolution reached and if so, how.....?
Thanks
Good Luck.
@Stewart.H.Marr
Billericay - Essex
Knowledge is knowing that a tomato is a fruit.
Wisdom is not putting it in a fruit salad.
I've also messaged Beebop direct.
@Stewart.H.Marr I hope this problem can soon be resolved.
@Beebop164 My Best Wishes to your Family I know as you get older things worry you more in this situation with good reason.