Underground drain... blocked or broken?

16 Aug 2012
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United Kingdom
Good Morning All,

Got a problem with the rain water drain for my house. I bought the house in Oct 2012, and has been on rent since. The tenent happens to casually mention that the drain has been blocked and water overflows out of the drain... and also the kitchen walls are a bit damp...

Going to give as much info as i know, relevant or not, it may help!

So layout is as follows:

The kitchen waste (sink, washing machine etc) all go into the drain on the right.

The gutter at roof level comes down into the drain in the middle (labeled as rain water).

According to my purchase survey, the toilet waste goes to the back, and long the back gardens, while the rain water goes to the front.

Now the floor height in the garden seems to have been raised some time in the past, where the original kitchen and rain water drain level is, is approx 5 inches lower then the current ground level.

The kitchen waste water drain is clean and water is freely flowing.

The man hole at the back i *think* is for toilet waste, though I couldn't check (toilet broken but that's a different story!)
It only has one feeder and one exit from what i can see by lifting the cover up, and based on survey paperwork, it suggests the sewage goes to the man hole at the back.

So back to the rain water drain, as stated, its approx 5 inches below what was the original level.

The drain itself is square, but sat at and offset - its at about a 60 degree angel from the opening.

It was covered in muck (tile sand/mud etc). I cleared this out to the drain cover level, and made some holes in the muck through the drain itself. Screwdriver went though the spaces easily, and spun freely inside, so im guessing that the drain itself at the top level isn't blocked. Tried to lift the drain cover, and it seems stuck, enough for me not to be able to pull it off with the tools i had available.

Water still fills up in to the drain when raining, and doesn't drain.

I cleared out some of the mud around the drain unit itself, its sitting in mud, and when i happened to touch a particular corner, all the water up to the drain cover level went down this hole...

So at present, I've got water filled in the actual drain unit, which isn't flowing away... I've got a cover which isn't budging.

I can only think that either the trap at the bottom of the drain is blocked, or that the drain pipe itself is broken/blocked...

Tried to contact Thames water to find out if they have any detailed drawing of where the pipe goes but got a response stating that they have nothing detailed, I've had a look at the front of the house for any man hole covers, and come up blank... nothing within the near vicinity of the house that i can find.

I'm guessing that the blocked water, and the gap on the side of the drain where the water is escaping into the soil, is then coming back though the wall as damp, which is aided by the fact that the previous owner seems to have rendered over the dpc, or has built up the garden area over the dpc...

So short of digging out the drain, and then possibly the pipe itself, any one got any ideas as to how i can check/clear the blockage? Can i push the rain water to the kitchen waste drain as a temporary solution while i dig/investigate?
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Scrape all of the crap away from around the gulley cover, and remove it (some cast iron covers have 'lugs' that perform as hinges) and get in there with the marigolds, wet vac or whatever....after that, its over to Andy :p
John :)
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The property is in Rayners Lane - HA2, think the problem isnt the weight of the cover, its *may* have got render/cement in it which has caused it to jam shut.. gonna go back with a bigger screwdriver when i get a chance and clear out the much around the joints and see if it budges... Problem was i went while it was drizzling so water was filling in while i was trying to clear it out!
Just to update and close this off,

Eventually with a hammer and chisel, i manged to pry off the grill part of the drain off.

Was full of water to the top, but also about 7" of mud below to the bottom of the trap!

Cleared it all out, along with pebbles and stones from the pebble dash from the wall, cleared out the outlet of the drain that lead to the trap. Stuck a hosepipe down it, and seems all clear!

I did clean up the grill, it shrunk by about 2 cm once it was cleaned - Was covered in rust, render and stones!

Will keep an eye on it but thankfully a cheap resolution!

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