Kitchen sink - water doesnt flow!

[nixon]

Hi guys,

I hope you can help me- I have been struggling with our kitchen sink for about a year now and still we haven't solved our problem.

This might be a bit of a saga - I'm assuming the more info I provide the easier it will be to fix!

Here are some general notes:

Drain seems to be blocked - a plumber came to unblock it and he used a wet vac to suck up the mess. About 10 vac fulls later (he was getting up rancid rotting food from the pipe) he recommended a man with a high pressure hose.

Nice guy with a van + hose turns up - jets the pipe from the outside, sticks a camera up the pipe and all is clear, but sink still not emptying. Sticks a rotary spring type clearer to a drill and goes down the pipe from the sink and eventually it clears.

Recently I've rodded from the outside and had no luck. Stuck a spring type clearer down (10m in length), felt no blockage and still the thing won't clear.

This leads me to asking for your help - do I simply have a blocked pipe or is this due to a vacuum/syphon or some other concept that I am unaware of?

Diagrams!

Under the sink:

I've noticed that the dishwasher is attached via a hose + jubilee clips. Do we need a proper one way valve here? Could it cause a vacuum?

Plan view:

As you can see we have a join under the floor - I cant see it (all concreted) however the waste from upstairs flows fine. Rodding from the outside normally means my rods go upstairs and not to the kitchen sink.

The only thing I can't work out is what sort of join exists under the floor where the pipe from the kitchen sink goes into the ground. Is there some sort of U-bend fitted into the ground that could be blocking? The house is about 8 years old if that helps.

Any help whatsoever would be very much appreciated

 

[theheatinghelper]

this is one of them jobs youve just gotta keep plugging away at. Presuming youve took the trap off and checked to see if there is any crap in it. i do a little thingy just to see if it is blocked..........whhoooohhaaa something just come to me.. have you seen if the over flow from the sink its self .........if theres a black pipe.. is that clear ????

if you take off the sink waste ... ( i know this is a bit dirty ) get ya lips around the pipe and blow. you`ll soon see if its blocked, ive done this before and with my own almighty ( bad) breath ive cleared a few blockages like this !!!!!!!!!!!!!!

 

[Burnerman]

I'm not to certain what I'm looking at from your plan view, but it would seem that the kitchen waste drain enters the downcomer from upstairs, and its on that joint where the blockage is.
Rodding or jetting from outside seems to allow the rods to go upstairs, rather than along the kitchen waste...fair enough.
I think, if it was mine, I'd disconnect the drain from the sink entirely, and use one of your spring type clearers to ensure that you can access the downcomer completely.
John

 

[nixon]

hi theheatinghelper and John, thanks for the replies!

I regularly take off most of the under sink pipes so I am left with a single pipe (that goes down, makes a right angle turn then finally drops under the floor) and I've tried a whole bottle of one shot (!) before, the garden hose (which had limited success) however I dont really want to blow down there!

What seems to make no sense is that the main pipe can be completely clear - as can the entire "under the sink" complex. I've even renewed it all just to make sure as I had a couple of leaky seals - yet something between the kitchen floor and the main pipe seems to be in the way.

I guess I'm asking this:

john - you could be right, however when the guy with the high pressure hose came (this was about 6 months ago), that entire straight was 100% clear yet the sink was still blocked!

 

[Burnerman]

OK thats clearer, thanks.
There's no need for a U bend to be where you suggest, but as the kitchen waste travels to the right, with hopefully a slight fall, does it then connect into a vertical soil pipe? If so, thats where the blockage is.
Using a nice flexible hose pipe is a good idea to 'mouse' its way along the pipe, but I wouldn't push water down it until I was happy that the exit was free!
John

 

[nixon]

awesome, thanks John!
I shall investigate more tomorrow. Since rodding would work if I could just get the flipping rods to hit the blockage I'll have to go with alternative methods! Im thinking the wet vac route since that seemed to work once before. Do you have any tips on keeping things running well?

 

[Hugh Jaleak]

This is a guess, but from the diagram you've posted the stack from the upstairs W.C. 'tees' into the 110mm pipe running under the house. I am wondering if there is an inadequate fall on the horizonzontal run, leading to some of the waste from the stack backing up towards the sink. I appreciate it was clear when the CCTV survey was done, but if the sink waste is clear up to the point it enters the 110mm under the floor I cant think of any other reason.

Its possible theres a 'soft' blockage of paper, water and solids in the pipe, not enough to stall a spring or rods, but enough to cause a plug which traps the air in the pipe and causes the sink to back up. (The water is trying to compress the air trapped in the pipe upon discharge and cant, so wont drain properly.) I cant see rods doing that sharp a 90deg turn to go up the stack personally, jetter could but I suspect gravity will let it carry on horizontally until it has no other option. It may be worth trying a 'half moon' scraper on the rods, see what they pull out from beyond the upstairs branch. Any amount of solids would indicate a build up in that section of pipe. Personally I think stack connections should be at the head of the drain, and any branches added afterwards so any possibility of backflow is eliminated.

Did your drains man CCTV the pipes before he jetted them? TBH if its bad drainage design then there's little you can do IMO to keep things moving, other than plenty of water down the sink. Fine, unless you're on a water meter.....

 

[Burnerman]

I completely agree with the above - I don't think there's enough fall in the pipe from kitchen to downcomer. This sort of testifies from your first post about the chap with the vacuum pulling out food debris. The fall on a drain is quite scientific really - it needs to be enough so that solids are carried along with the liquid to keep things clear.
Anyway, assuming that the thing clears eventually.....minimise what solids go down the sink, don't use a waste disposal unit if there is one, get plenty of water down there and a good dose of bleach from time to time does keep things wholesome. I'm not sure how effective such treatments such as 'plug unblocker' would be over such a long pipe run.
John

 

[nixon]

Once again, thank you for the replies (what an awesome forum!).
I spent some time investigating and this is what we have found:

Disconnected everything from under the sink and got the wet vac on there. It pulled up at least 20 litres of foul water.
I flushed some toilets from the upstairs and they still flow ok.
I got the garden hose and directed water into the pipes at the sink end - filled up about 20 litres until it backed up into the sink.
Turned the wet vac on blow which was rather stupid - it blew the pipe off where it enters the ground in the kitchen!

Anyway, moving on.... I know that it seems we have a double (or even triple) trapped drains! We have a bottle type trap under the sink, a U bend also under the sink and then a trap in the ground under the kitchen. This explains why the jet washer cleared the main pipe but the kitchen sink was still blocked (and then why aggressiving rodding with a spring type thingy finally did the trick).

This trap in the ground holds water, yet seems to be so "sloppy" that its really hard to get any water through it.

This drain is now at a point where it is passing a very small amount of water (takes about 10 minutes to drain a half full sink).

The current advice from a plumber is getting someone in to dig up the trap in the ground and to replace it with a normal join (i.e. not a trap).

This got me thinking - are double traps allowed?!

 

[Burnerman]

You know where you blew the pipe off, where it enters the kitchen floor? Is there any mileage in getting your wet vac in at that point, and sucking clear more grot?
You say there must be another trap under the floor? I've never heard of that one.....I'm wondering if it has had anything to do with previous works on the house.
You are keeping us entertained - at your expense!! Good luck with it.
John

 

[Nige F]

You know where you blew the pipe off, where it enters the kitchen floor? Is there any mileage in getting your wet vac in at that point, and sucking clear more grot?
You say there must be another trap under the floor? I've never heard of that one.....I'm wondering if it has had anything to do with previous works on the house.
You are keeping us entertained - at your expense!! Good luck with it.
John

hidden trap on the drain ...more to do with an eejit who put it in when the place was built

 

[nixon]

You know where you blew the pipe off, where it enters the kitchen floor? Is there any mileage in getting your wet vac in at that point, and sucking clear more grot?
You say there must be another trap under the floor? I've never heard of that one.....I'm wondering if it has had anything to do with previous works on the house.
You are keeping us entertained - at your expense!! Good luck with it.
John

hidden trap on the drain ...more to do with an eejit who put it in when the place was built

this is my fear! im fairly sure when drain-cam-man appeared his little tv showed the main pipe and then a bend downwards. Also when i put the thinner spring thingy down the pipe it certainly does get caught a number times (which maybe a bend).

I'll stick me wet vac into the hole int he ground and see what we get - this is very entertaining indeed!!!

I was hoping someone might say "omg its so illegal get it done under the NHBC"... i know that might be a lot of effort but im willing to explore all of the options.

 

[Hugh Jaleak]

I'd be extremely surprised is there's a 'U'bend under the floor but always a first time! There was another thread on here not so long ago about similar issues with poorly designed drains under a house. I assume from th NHBC remark this is a fairly modern property??

 

[nixon]

yes its about 7 years old. i might shove my webcam and a torch down there and see what I can find! :O

 

[Homesafe]

Once again, thank you for the replies (what an awesome forum!).
I spent some time investigating and this is what we have found:

Disconnected everything from under the sink and got the wet vac on there. It pulled up at least 20 litres of foul water.
I flushed some toilets from the upstairs and they still flow ok.
I got the garden hose and directed water into the pipes at the sink end - filled up about 20 litres until it backed up into the sink.
Turned the wet vac on blow which was rather stupid - it blew the pipe off where it enters the ground in the kitchen!

Anyway, moving on.... I know that it seems we have a double (or even triple) trapped drains! We have a bottle type trap under the sink, a U bend also under the sink and then a trap in the ground under the kitchen. This explains why the jet washer cleared the main pipe but the kitchen sink was still blocked (and then why aggressiving rodding with a spring type thingy finally did the trick).

This trap in the ground holds water, yet seems to be so "sloppy" that its really hard to get any water through it.

This drain is now at a point where it is passing a very small amount of water (takes about 10 minutes to drain a half full sink).

The current advice from a plumber is getting someone in to dig up the trap in the ground and to replace it with a normal join (i.e. not a trap).

This got me thinking - are double traps allowed?!

The trap you refer to can be pumped quite viciously with a mop(old style ) and it will clear it.

i had a similar problem and the mop trick sorted it.

it is just grease and other **** that gets the drians to block up.

hope you sort it