I think the outlet to the kitchen sink has frozen up outside, it’s a big cast iron pipe coming out the wall outside but when I empty the sink it’s all running down the wall inside the kitchen where it meets the outlet. Surely if it was blocked/frozen it should back right up into the sink?? Does this suggest dodgy plumbing into the outlet? Problem is this is all behind cabinets but I can just see this happening when I pull out the dish washer and shine a torch in there. Anything I can do other than rip out a cabinet/cut a hole in the back of one. Boiling water didn’t help but who knows where it’s frozen, under ground probably. There is a seriously old nut at the top of the bend outside but I’m guessing it’s just rust under years of paint. Any ideas??

Could be the pipe has split due to freezing.

think it’s going to be a cut out back of unit job

Dishwasher and washing machine drain hoses often just sit in an open pipe below sink level. If the water backs up it’ll come out of the pipe before the sink fills up. Could this be happening?

No it’s definitely at the wall at the outlet, it’s not making it back as far as the washing machine and dishwasher connections

Blown a gasket?

Ah. No idea then.

Disclaimer: I am not a plumber or a builder.

In general underground pipes in the UK are buried deep enough that they will stay above freezing temperatures, and any water in the vertical pipe above ground should drain into the underground pipe before it freezes.

I guess it’s possible if the ground temperatures are unusually low enough for a long enough period (or the pipes were not buried to a sufficient depth) that water could freeze in the underground pipe. I suspect it would be more likely that the cast iron pipe above ground is so cold, that water in contact with the inside face of the pipe is freezing, and building ice up in layers, progressively restricting the flow inside the pipe until it is completely blocked. If the latter, you are probably going to have to wait for outdoor temperatures to rise above freezing and for the ice in the pipe to thaw (unless you can apply heat to the pipe yourself, which is likely to be tricky and possibly risky: cast iron has a high thermal mass so will require a lot of energy for a given rise in temperature, and it does not like undergoing extremely rapid heating or cooling which can cause thermal shock and might crack it).

Same has happened to me… well almost. Water down kitchen sink is causing water to back up and out the washing machine drain and on to the kitchen floor. I tried pouring boiling water on pipe work and that hasn’t worked.

I’ve stopped using the toilet too as the last thing I want is for that to back up and onto the kitchen floor!

I am just wait till it thaws. But you could using a hair drier to try and unfreeze the pipe work.

Think I need to cut me a peep hole.

My vote is the old cast iron pipe is a different size, and someone has bodged the modern metric sink drain into it.  Now the outside pipe is frozen (or blocked) the connection is leaking.

Might be able to get better access by removing the sink/worktop rather than hacking the cabinets?

Have you checked your drains outside? If you can lift the nearest inspection chamber lid to your house, do so and check you don’t have a blockage in there.

If it is clear, frozen pipe above ground sounds likely, along with the previous bodge of plastic waste pipe into the original cast iron soil pipe.

Just leave the freezer door open.

Won’t fix the issue, but you might get some comedy cat/mouse capers to keep you amused.

If its  like my place there  might be  4″  cast iron vertical riser  with a vent at the top which doubles up as  kitchen doownstairs and bathroom upstairs , There should be a vent at the top. If you have a very long ladder and are feeling brave a kg of  dishwasher salt  poured  down might shift the ice.

Due to the specific heat  capactiy of ice V boiling water , you wont melt  a plug of ice with a kettle . Better  solution would be  a blankets wrapped round then hot tap water poured  down . Hot Tap water is around 65’c  so should not crack   the iron.

My  cistern feed O ring failed  last night and I had a flood and now and toilet-less  till I  can get to screwfix .

This pesky ‘beast from the east’ I’ve had enough of it now. A load of salt and boiling water at the hottest part of today, 1c or so, seemed to do the trick. I’ve got the fear now again tho as it’s Baltic will leave it until same time tomorrow and try again. Defo sounds like a dodgy connection into the pipe but it’s not a proper soil stack so salting it from the top isn’t an option.

Without seeing the situation no one can say for sure but I do diy for both myself & as a job I’ve seen so many shocking bodges,where lazy incompetent previous workmen/owners can’t be arsed so just do ‘minimum necessary’ even not spending money at all.

I had a bath panel that I had to smash off cos someone glued it on to cover holes up in the internal wall they couldn’t be bothered to fix,then discovered the bath had a rotten overflow pipe for god knows how many years untouched had damaged the floor I got to it in time !

Delt with a house for a friend dry rot throughout the downstairs we had to remove the whole floor & replace all the timber, cos a dick had blocked the air vents front to rear of the house ! Going down that same road lots of vents are covered over on other houses & I’ve seen this in other areas too,so a simple vent,water leak etc can lead to major problems if left not to mention the costs putting it right.

Moral of the story get it looked at & repaired properly believe me you don’t ever want to see how bad it can get.