Drain blocking

Yorkie1

I live in a 1930s semi-detached house (say, number 10) joined to number 12.

The drains run along the back of the houses, from number 2 down towards number 14 and so on. The manhole cover is about 1m from the back door.

I have a grate into which the water from the bathroom, dishwasher and washing machine pours (from pipes that end just above the grate). The sink's drainage pipe just goes down to the bottom of the under-sink cupbard; it doesn't have an above-ground external discharge pipe, so I assume it either goes down and out there, or somehow bends round the back / side of the corner cupboard to join up with the dishwasher waste?

A year ago, the water in the grate wasn't draining away, so the water spilled onto the concrete and then drained into the ground around it. I got a local firm in to unblock it. Now we're 13 months on, and it's blocked again.

I've been here 16 years and last year was the first time it's happened. There's no change in how I use the drains or machines. It's the same neighbours upstream and downstream, and I doubt they're doing anything different.

The only change is that number 8 Ii.e. the first house upstream) had an extension a year or two ago. Their ground level is 4' higher than me, and they had to move their manhole sideways so that it was still outside what was now their new extension. From memory, there was a deep tube from the manhole down to, what I presume would be, the drainage line.

I can't see how this might be related, but could it be possible?

Might there be any specific questions to ask of the local firm, when they come round later this week, which might be helpful to find the cause?

Grateful for any thoughts.

EssexExile

Surely if it's a shared drain it's up to the water company to sort it out?

Via Google:

Shared Lateral Drain: Since October 2011, most shared lateral drains (pipes that carry wastewater away from more than one property) are the responsibility of the local water company, even if they run under private land. If the blockage or fault is here, the water authority is legally required to clear it at no cost to you.

gwynlas

It sounds plausible that debris from building work is causing a blockage somewhere along the run.

I think the only way that you would find out would be by having a camera led drain survey.

Unfortunately unless other neighbourss have commented on similar then you would have to pay

Section62

https://forums.moneysavingexpert.com/discussion/6669739/drain-blocking

There's no obvious reason work on the upstream side would affect you (unless it restricted flow below self-cleansing velocity), but one of the things to consider is whether the owner/builder allowed mortar/concrete (e.g. mixer washings) to get into the drain which have solidified further down the line.

But if their drain goes into yours and yours into 12's then the drain run is probably a public sewer, so you could get the water company to investigate/clear it. The pipe from the gulley to the shared run is probably private though, and the water company may argue that as the water is coming out of the gulley then it is your problem to fix.

Yorkie1

Thanks everyone. I'll leave the appointment as it is, and ask them questions about what they see that might be the cause - and exactly where the blockage is.

Then, if it happens yet again, I'll contact the water board.

I mentioned it to my neighbour (number 8) at the weekend, and he'll see if he can find time to lift the manhole on his land and spot anything - though I'm not hopeful.

WIAWSNB

Hi Yorkie.

You say your manhole cover is just a metre from your back door? And this manhole cover is inline with the main sewer that you all share, and to which your house connects? Cool. In which case, unless your blockage is in that 1m run, it shouldn't be your issue to resolve. And if it is, then you only have 1m of pipe to investigate.

What do you see when you lift the cover? If the main lateral run from the lower-numbered houses and passing past yours is free-flowing, then it suggests that the blockage must be between your house and this manhole - a mere 1m run.

If, however, the manhole is backed up, then it's the WB's issue to resolve. And hopefully they'll find the root cause.

Picture, please?! 😶

FreeBear

I used to have an "issue" with my drain getting blocked at the point where the pipe entered an inspection chamber - 1920/30s vintage with glazed clay pipes. After sticking my head down there and feeling around (with gloves on), found there was a snot of mortar that would collect toilet paper. The issue was aggravated by a lodger that would get through a whole toilet roll (or more) per day.
Chiseled away the mortar snot as best I could, got rid of the lodger, problem solved.

Gonk1967

When does the flooding occur? is it a regular occurrence or only during certain rainfall events?

It could be possible that when the upstream neighbour had his extension built, the additional run-off from the extension roof increased the flow above the capacity of the downstream pipework.

Yorkie1

Thanks WIAWSNB - I don't have a tool to get the manhole off. But I am not working on Thursday, when they are due to come, so I will get them to lift that first and have a look down. As you say, the blockage is either:

• In the grate / gulley itself
• In the 1m run from the grate / gulley to the main lateral run (which, as you and others have pointed out, is my responsibility)
• In the main lateral run downstream from where the grate / gulley joins it, to the manhole cover
• In the main lateral run, downstream from the manhole cover

I've attached a photo below. You can see a white pipe coming in from the left, from which there is a trickle of water coming. That is the pipe from the dishwasher (and kitchen sink). There's another pipe hidden underneath it which is from the washing machine. And the bathroom water waste is the poor condition red pipe from above.

The standing water level was about 2-3" below the level of the grate when I just went out to look, before I switched the kitchen tap on (which is the trickle of water).

Yorkie1

https://forums.moneysavingexpert.com/discussion/comment/82011231#Comment_82011231

It seems to relate to when the water has discharged into the grate; the water comes from the sink / bathroom / dishwasher / washing machine.

So not to do with rainfall, as far as I can tell.

FreeBear

Water level should be 100mm (or more) below the grid,

The bottom white pipe needs a bend or shoe on it to ensure the waste water goes in to the gully. As it currently stands, water could flow in to the gap between wall and gully leading to damp. The upper white pipe could also benefit from a shoe/bend to make sure water goes where it should.