Blocked Waste Water Drain

[sammey]

Hi Guys,
I really hope someone can advise as I'm at the end of my tether!

The waste water drain at the rear of my house drains waste water via three pipes from my bath, washing machine, dishwasher and sinks. It's been slow to drain for some time and I should have taken action earlier but it's now completely blocked.

So far attempts to clear it have completely failed - I've tried a one-shot chemical treatment, metal drain snake, and the angle is too acute to get a drain rod down it. To make matters worse I took up the manhole cover in the garage (which is in line with the sewage line) for the street and it's been made redundant / blocked. It seems likely this was done when the extension was build in the early 70's. We are a semi-detached house at the top of the drainage line of four houses. Our immediate neighbours 'downstream' from us do have a manhole cover, but theirs seems to be running perfectly on inspection.

Would it be possible to clear the blockage from my neighbours manhole, or is the only other option to try and clear the drain with a high pressure jet applied directly into the drain itself?

Any advice would be most appreciated!

 

[Hugh Jaleak]

Depends where the pipe goes upstream from the neighbours manhole. If the gulley connects via a branch, and the blockage is upstream of the branch then rods or a jetting hose wont be able to turn into the branch pipe to reach it.

I'd try plunging the gulley forcefully to see if the pressure you create will move anything. Having used chemicals be extremely careful if you try this. If this doesn't work then jetting hose from the gulley is the other option. If engaging a contractor warn them you have used chemicals!!!

What exactly has been done to the original manhole under the garage?

 

[ChrisR]

The waste water drain

Which pipe do you mean? A 110mm soil pipe is unlikely to block. If it's 40mm, if necessary cut it and use a compression coupler afterwards.

 

[sammey]

Hi many thanks for the post and advice!

I did try plunging quite forcefully with a plunger on a rod before popping the chemicals in for quite some time. It did draw out some toilet paper / sewage etc. but the blockage didn't clear up and I wasn't quite sure why it would be drawing sewage / foul through the waste water drain? If you think it's worth giving it another go I will do (with care as advised).

On removing the manhole cover I saw a pipe , one end of which had been stuffed with plastic sheeting to block it, and the other end of the pipe ran under the house, in line with the main sewage line (as far as I could tell) but was dry. I put the drain rod a couple of meters into the pipe and it came out covered in mud! I don't know if this terrible drawing helps illustrate what I mean but I've attached it just in case. Thanks again!

View media item 29068

 

[ChrisR]

We don't know how your drains are organised, so I'm still not clear what pipe you're talking about. Basins and sinks are separate from loo sewage until they join the big stack pipe. Or, the two could be separate until they get to the manhole. The blockage is likely to be in the smaller pipe. Measure it - 42mm or so??
Is the loo backed up as well?

Builders to all sorts to block old pipes, a plastic bag full of *&£@! is about average!

 

[sammey]

Hi Chris, thanks for your patience. I'm not familiar with the terms, but the blocked drain in question is at least 110mm in diameter I'd say. It goes vertically down into the ground outside the house, and makes a sharp 90 degree turn under the house foundations towards the bathroom / loo. It's served by three plastic waste water pipes around 42mm I'd say that lead from the sinks, washing machine, dishwasher etc. It's the large external drain that's blocked and overflowing not the thinner plastic pipes leading to it.

The loo is working fine - so no problems there. When the loo is flushed, the level of un-drained water in the blocked drain rises and falls. Hard plunging of the drainpipe brought out some toilet refuse so as you say the two are connected, but I'm at a loss as to where the block must be if the loo / sewage isn't backing up but the waste water is? Thanks again!

 

[Hugh Jaleak]

Site seems to be working again....

Assuming loo is upstairs? Blockage is affecting the loo by the sound of things, if the level in the gulley is rising and falling, thats because the water from the loo when flushed is altering the pressure in the drain behind the blockage. Can you amend the drawing to show where the 110mm pipe from the loo goes into the ground?

If you could indicate where the pipes from the neighbours manhole go, and the direction of flow that might help too.

 

[sammey]

Hi Hugh,

Actually the loo is downstairs (I probably should have mentioned that). Thanks so much for your help - I'll try and organise a more detailed diagram this weekend.

 

[molsden]

Just followed Hugh Jaleak's suggestions of plunging our outside drain which was permanently blocked and hay presto! we have drainage. Great place to look for tips. :