DIY Doctor

Blocked Drains

Postby JeffB » Sat May 08, 2010 7:52 am

I have fitted a new toilet system on the ground floor which has the standard 6ltr flush. Since then the underground sewer pipe has blocked twice. (too bigger job for Mr Muscle drain cleaner) so I have had to clear it. I think it is because the amount of water in the flush (6 ltr) is now not sufficient to flush the waste away to the main street sewer. It has been sugested that I need a "High level syphon" which should solve the problem. Any advice please. Many thanks.
Last edited by JeffB on Mon May 10, 2010 3:25 pm, edited 1 time in total.
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Postby Dave From Leeds » Sun May 09, 2010 3:29 am

Hi Jeff,

I assume that the following should read NOT sufficient rather than NOW.

"I think it is because the amount of water in the flush (6 ltr) is now sufficient to flush the waste away to the main street sewer."

Don't know the answer but I'm due to replace my syphon loo by one of these dual flush 6 litre affairs in the next three months. mind you, mine's upstairs.
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Postby JeffB » Mon May 10, 2010 3:24 pm

Hi Dave from Leeds

Thank's for your reply.

Shame you don't have a fix maybe some one else can help and advise on a solution. Thx

PS You were correct is should have been "NOT Sufficient"
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Postby Barry Bunsen » Tue May 11, 2010 8:34 am

I may have misunderstood the problem but couldnt you check if the 6 litre volume of water is causing the problem by temporarily flushing with a bucket of water to see if the problem clears up. There could be a gradient issue or a partial blockage which needs sorting. Was everything working well with the old flush?
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Postby htg engineer » Tue May 11, 2010 6:37 pm

A 6L flush should be ample.

So probably a problem with the drains, not enough fall - partial blockage.

Whether you go for getting a drain specialist to check with camera or opt for a larger cistern (cheaper option) is up to you.

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Postby JeffB » Tue May 18, 2010 1:15 pm

Hi Barry & htg Engineer.

Many thanks for your replys... I have to say I feel tyhe problem is with the flush as I never had this problem until the 6 ltr flush was fitted .. whilst I agree there could be damage there has been nothing visible on the surface to suggest damage. No cracks in the ground No trees near by so I do feel the problem is the lack of flush. I am still monitoring the manholes to see if I can detect a problem. Many thanks JeffB
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Postby BigRod-BidefordDevon » Sun May 22, 2011 2:54 pm

Hi, I have come across this a number of times over the years and every time it has been due to debris inside the drain from the old toilet being taken out.

There have been three main causes, the first being pieces of ceramic where the pan has been broken out with a hammer. The second has been where a piece of clay collar has broken off the drain itself where the pan has been cemented in and the third is the rubber ring ring seals from the pan connector.

You would be surprised how often I have received a call after plumbers have replaced a pan to find one the above has been causing frequent blockages.

I have one question though, did u follow the instruction for installing the cistern, some have to be adjusted inside to allow for tank or pressure filling. Others have an adjustment for water volume, these may have an effect on the efficient filling/flushing of waste. However the amount of water used or not used should not be the cause blockages within the underground drain.

Obviously this is not going to be easy for you to address, not having a drainage camera, what I would suggest before u go to to much expense and inconvenience is to flush out the drain.

Either, take out the pan and then push drain rods fitted with a plunger head up from the manhole to the bend beneath the the pan and see if any debri is pushed up to allow removal. You may even be able to fell if there are any faults (i.e. offset joints) along the drain. Or borrow/hire a drainage bung, place this at the manhole end of the drain and fill the pipe with water by flushing the toilet until the drain is filled. Remove the bung and allow the water to flow at full bore, this should flush out any debri but make sure u have a spade placed in the manhole channel because u do not want the debri to wash further downstream.

I have seen many drains that have none existance falls or even slight backfalls and multiple offset joints where the occupior has never had blocked drains occur. I have also surveyed many many drains with severe faults that do not display and fault at ground surface.

Hope this helps

Best of luck

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