Dodgy kitchen plumbing ?

I've done a recce online and can't figure this out so hoping someone can shed some light.
Have always had problem with the kitchen sink draining unreliably, it's a double sink with an offshoot to dishwasher. The plumbing is not pukka (no it was not me who did it) and has some issues, however not sure if this entirely accounts for the problem - pipes that I can see are not all properly downwards sloping for instance. Also much of the pipework is behind kitchen units, grrrr.
Problem is I can't really get the problem to stay consistent. It drains well for a while after being sorted (snaking, plunging, cleaned out the p bend etc) and then starts draining slowly. Am v careful about gunk getting down it so don't think that's the problem.
What I'm wondering is, is it an air vent issue? It doesn't have one as far as I can see. Or does the overflow grill thingy in the sink act as an air vent?

Here is a photo, please no snarky comments about messy undersink area I'd just finished reaming it all out and chucked things back.



Cheers
GG

 

Before you start taking things apart there GG check your drains and pipework outside, they may be blocking and causing back up. I flush my drains regularly with a water jet on my hose which helps keep them clear as the 'runaway' doesn't slope very much.

 

I had all sorts of problems with mine, washing machine was vomiting back up into the shower.

Then I found a tea bag was blocking the outside drain Problem solved.

 

I've had a 12' snake from the sewer outfall outside under the drain cover wotsit beside the house and that was pretty much ok except from a few bits of sludge, ceramic outflow pipe seems very clean itself. It's a fair way from tap to outside where it meets the sewage drain so there could be an odd section of pipe my snake doesn't reach, but in general not found a serious blockage.

Cheers
GG

 

Cor, a 12 foot long snake! I've only rescued an 18 inch long grass snake from the gulley outside my kitchen (+ a few frogs).

 

Sorry, not wanting to treat you like an idiot but have you checked the flow through the drains as the blockage could be where you can't get to it. Fill the sink up, pull the plug and then dash outside to check the flow, also flush your loo and check again, it's surprising where a blockage can turn up and affect other places.

You say the dishwasher empties there, what about your washing machine? Using powders in machines is one of the worst culprits for blockages, I changed to gels/ liquids some years ago which doesn't gunge up like powders.

 

Another thought.....do you use a dishwasher cleaner regularly to flush it's system through?

 

All good ideas Sheal and a while since I've gone through each section of the pipework to check. I think I'll do some testing again as you suggest and check further down the sewer pipe which is where the washing machine drains in. Have to wait for the weather to clear first.

I am still wondering about the air vent question though ...

thanks for suggestions all.
GG

 

I think the overflow vent will provide air intake but you could try squirting some bleach or similar into it just to check it's clear.

I think if you have an issue with the pipes under the sink it's got to be the one from the right, that looks to me as if it's sloping down and that's where you'll get any build up. I presume you've checked the 'trap' at the base of it?

 

Thanks Sheal and FC. I think you might have a point there FC on the reconfiguration (btw nice little diagram there!), but typical lazy sod that I am, was hoping for a quick fix. I think I might have the required elbow joints already so ...
Before I do that I'm going to really test the system from the top, bottom and a halfway point that I can get to and then decide what to do. Of course, should have done this ages ago

Cheers again
GG

 

Good write up FC
GG it does not matter what clearance you make, you will have to correct the plumbing to FC drawing, or you are trying to drain water up hill, All of it will not drain out of the pipe and you are going to have one real bad smell, direct from the drains outside if you do not fit the U bend

Jack McH

 

I'm wondering why the this additional fitting has been used (that lowers the horizontal pipework so it falls to the wrong direction).

I can't see how close the copper water supply and waste pipes are to one another, but it appears as if the pipe may have had to be lowered to keep the nut on the T fitting from conflicting with the copper pipe behind.

Is that the case? If so then it might explain the bodge up.

 

Well, status update, but thanks for everyone chipping in with useful ideas.

Scrungee - that additional fitting, yes it does look unnecesary, it is the sink outlet thread to Tee adaptor, I can only think they put it there because the Tee looks to be the wrong size (slightly larger) than the rest of the pumbing up there - what I need is a Tee section like the one on the left.... Anyway before tackling that pipework I thought I'd have a proper systematic examination of problem, I'd not really wanted to do this as I was afeared that the problem might be where the pipe goes underground for quite a few feet before it reaches the sewer outflow. I digress.

Halfway between sink and outflow the outlet pipe is accessible via a joint in the sunroom (an extension). Disconnected that, turned sink hot tap on and let it flow into bucket, top notch flow, so no serious probs there.

For the second lower section of the pipe, snaked yet again from sewer outlet and got 12' up and plenty of silty stuff and also plenty of white putty like stuff which niffs a bit, the putty-like stuff came away in bits with some large pieces about size of a thumb, it has a putty like consistency and is greasy, holds it shape until worked between fingers. Not sure what this is. Veggie household here but as I said this flow has been problematic since we moved in so who knows whats been chucked down there in the past. Anyway reamed it out good style while running hot water.
Tried to snake it from sun room connection towards sewer pipe but it was tricky going but felt perhaps a few obstructions, but didn't get the snake in as far as I'd like.

Put everything back together and ran hot water down it for a good while and it is flowing like a good 'un with no backup at all into sink.

I'm hoping this is a solution but I'm fairly certain there are difficult to get to bits of the pipe (it's a long run, I guess about 30ft of pipe from sink to where it joins the sewer section that runs alongside house - crazy I know but house is c1900 build with extensions) which are gunked up. I'm going to look for some sort of cleaning option.

Anyway, fingers crossed it is on the mend.

Thanks once again for all the help.

GG