Rainwater drainage

littleteapot

Hi all, I own a 1930s mid-terraced house which is built on clay soil. They are known to have shallow foundations (only about 2 feet according to my neighbour) so there are many signs of minor historic movement (mostly small cracks in the internal walls and ceilings). However I became more concerned when I noticed a crack in the exterior render a couple of weeks ago whilst weeding. I'm not sure how long it has been there, maybe I just didn't notice it before.

Whilst it was raining heavily this weekend I came back in the car and when getting out of the car I noticed the flowerbed at the front of the house flooded and water bubbling up where the downpipe goes into the ground.

I'm assuming the pipe in the ground leading to the soakaway is blocked and needs cleaning out.

I also noticed that my house has the only downpipe - collecting water from all four houses in the terrace. Seems a poor design to me but looking at the other blocks of 4 houses in the street they are all the same.

Thanks in advance for any thoughts or advice.

ThisIsWeird

No idea about the crack. But it does sound as tho' the drain is compromised somehow.
If it's an original 1930s drain, then I suspect it simply joins the main sewer system, so it could be that the gulley - the bit in the ground the DP goes in to - just needs a clean. That should be easy to check.
If instead it's a soakaway, then it should be well away from the house - at least 5m is the current requirement, I understand.
How does the land terrain lie - no chance there's a ditch running at the back of the garden, or anything like that?!
It might seem unfair that only one house has the shared DP, but that's the way it often is - and you mustn't change that without agreement. But, check yours and a neighb's deeds (£5) and see if they have a shared responsibility for its upkeep - it would certainly be the morally fair outcome.
It could even be that the increased, higher intensity, rainfalls we seem to be getting these days will simply overwhelm even a fully-functioning system, in which case you and your neighb's may need to discuss a way forward on this - potentially tricky.
I can't see insurance being interested, as if it's down to a blocked drain, then that will surely be considered a lack of maintenance.
Suggest read deeds first.

littleteapot

Thanks, I hadn't considered that it might join the main sewer. I guess they did things differently back then. I know that nowadays it isn't permitted to route rainwater into the sewer system.

The downpipe goes right down into the soil. There isn't any visible gulley. So I guess I'll need to hand-dig around the downpipe until I see where it goes. There are no inspection covers in front of my house nor any others in the street, so that leaves only 3 possible ways for it to go:

1. Into a local soakaway (unlikely based on what @ThisIsWeird suggests as there is only about 7m between wall and pavement/road so meeting the 5m requirement may be tricky).

2. Underground pipe going to the rainwater drain in the road

3. Underground pipe going under the house to the sewer that runs along the back of the house (Surely they wouldn't have been stupid enough to build it like this but anything's possible!)

Yep I was well aware that I am not permitted to alter the arrangement but I will do the deeds check as suggested to find if there is a shared responsibility.

FreeBear

ThisIsWeird said: If instead it's a soakaway, then it should be well away from the house - at least 5m is the current requirement, I understand.

Regulations say a soakaway should be a minimum of 5m from a building or road, and a minimum of 2.5m from a boundary - Note the use of the word "should". So it is a recommendation, not a mandatory requirement.

OP - If you are digging up the drain, you will probably find the underground pipe blocked with roots. Once you've managed to unblock it, I'd suggest fitting a debris gully at the bottom of the down pipe - Makes it easier to monitor, and traps a lot of the muck before it gets in to the drain/soakaway.

littleteapot

FreeBear said:

ThisIsWeird said: If instead it's a soakaway, then it should be well away from the house - at least 5m is the current requirement, I understand.

Regulations say a soakaway should be a minimum of 5m from a building or road, and a minimum of 2.5m from a boundary - Note the use of the word "should". So it is a recommendation, not a mandatory requirement.

OP - If you are digging up the drain, you will probably find the underground pipe blocked with roots. Once you've managed to unblock it, I'd suggest fitting a debris gully at the bottom of the down pipe - Makes it easier to monitor, and traps a lot of the muck before it gets in to the drain/soakaway.

That's an excellent idea. I was going to dig out next weekend to inspect, so I will install one of those if I manage to find and resolve the problem. Hopefully it is just small roots and other debris. Failing any obvious issue or simple remedy I'll get a drainage expert with an inspection camera to investigate at whatever cost that comes. I certainly don't want to delay and end up with more serious problems (if there aren't already).

More likely though there is further damage as the council have trees at regular intervals along the pavement, one of which is roughly in-line with this downpipe and so given that the council no longer bother to keep their trees under control, it's roots are likely to have infiltrated and damaged any underground pipework or soakaway.

FreeBear

Dig a bit more out - It would be interesting to see what those two clay pipes are for and where they go off to. They might be vital foul water pipes, or they could just be rubbish left over from the last time someone was digging a hole there.

Certainly, the water from that downpipe needs to be piped well away from your house - I don't subscribe to the notion that "it has been like that for years, and won't cause any problems". Just do a search for "sink holes opening up in gardens", and You'll see it can be a big problem. Even if you don't get a sink hole, there is a good chance that the foundations will be affected at some point in the future.

CSI_Yorkshire

FreeBear said:

Dig a bit more out - It would be interesting to see what those two clay pipes are for and where they go off to. They might be vital foul water pipes, or they could just be rubbish left over from the last time someone was digging a hole there.

Certainly, the water from that downpipe needs to be piped well away from your house - I don't subscribe to the notion that "it has been like that for years, and won't cause any problems". Just do a search for "sink holes opening up in gardens", and You'll see it can be a big problem. Even if you don't get a sink hole, there is a good chance that the foundations will be affected at some point in the future.

"It hasn't broken yet" isn't really good evidence for future longevity.

Certainly, "I haven't died yet" doesn't make me immortal.

ic

You said this downspout handled your neighbours water too?  In which case you should get your local water board out to sort it - its their responsibility to look after any shared drains - at their cost.

littleteapot

ic said:

You said this downspout handled your neighbours water too?  In which case you should get your local water board out to sort it - its their responsibility to look after any shared drains - at their cost.

I thought that only applied where the guttering downpipe is connected to the sewer system - not when it terminates in a soakaway within the boundary of the property(s)?