Slow utility sink - is a pump the answer?

[RonSwanson]

Hi

I'm wondering if anyone can recommend an under-sink drainage pump which would help drain a utility sink on a long horizontal run, in the UK?

Background:
I have a problem with the sink in our utility room draining slowly. Because of this, when the connected washing machine pumps out waste water, it fills the sink first before draining away.

I've checked for blockages in the pipework above the floor, but it seems the issue is below. It's been rodded and had drain-cleaning acid put down without much effect. I don't have good access the waste pipes, but I can see it's a fairly long run - around 10m including a right-angled bend. There's very little fall on the waste pipe from what I can tell.

Ideally the entire pipe run would be replaced with a larger diameter, and a decent fall but since I can't do that, I'm wondering if the solution would be to get some sort of pump. They seem fairly common in the US for basement laundry but not so much in the UK. Price is obviously important too. I doubt it needs to be very powerful.

Thanks

 

[Elkato531]

Saniflo do one. Think its the sanivite but check the website. On such a long run with inadequate fall, the pipe may have sagged somewhere causing water to sit in the pipe rather than drain properly away. If possible, the best bet is to sort the waste pipe correctly.

 

[oldbutnotdead]

10m of small bore pipe with no fall is asking for trouble. The pump idea might or might not work- they're really designed to lift the waste water a couple of metres (and then let gravity do its job) rather than to effectively pressurise a poor drain. It might be worth trying an air admittance valve (after the sink), the best bet would be to redo the waste pipe in the correct size with the correct fall. If you can't do that because its a rented property (and the landlord has supplied the washing machine in that location) then get on to the landlord and get him to fix it.

 

[Madrab]

If the pump in the washing machine backs up into the sink then another pump wont shift it any quicker, it cant drain fast enough to start with so adding another pump will just cause more problems, you need to find the restriction and get it cleared.

A 10m waste run is not ideal either and should really be looked at to see if it could be shortened.

 

[Ian H]

Are there not any drains closer than 10mtrs?

 

[just pumps]

As Madrab say`s adding a pump is not the answer you are just wasting money and storing up problems.

 

[RonSwanson]

Thanks for all the replies. A lot to think about.

The reason I can't replace the pipe is down to cost. We had a new kitchen and floor fitted fairly recently, before we had discovered the extent of the problem. The utility room is effectively an extension to the rest of the house so is separated from the kitchen by an external wall, with two rows of brick (laid end-on). The direct line to the nearest stack is 5 metres, but that would be through both walls and under the new floor. The crawl space under the utility room is around 1 foot below joists, so 18 inches below floor. I have no access to the crawl space in the main part of the house.

The pipe goes ~5m to the front of the house, turns 90 degrees and meets the kitchen sink waste 2.5 metres further on, and then goes to the stack. We had no issues with the kitchen sink (and connected dishwasher).

There's a rain water drain about 2 metres away but they're separate systems where we are.

We had a durgo valve fitted but it made no real difference.

I was hoping a pump which is designed to pump vertically would be able to move the water along, but I guess it's normally pumping into an empty pipe rather than one which has water sitting.

So, if a pump isn't the answer and I can't replace the pipe, I'm stuck pretty much stuck with it?

 

[oldbutnotdead]

Can't work out the layout from your description- a sketch would help (I do mean sketch- back of an envelope, photo on phone, post).....is there any access to outside from the utility room, ideally on the same side of the house as the stack (it might be possible to put an additional drain in to meet the stack underground, it might be possible to run a new bit of 40mm at a higher level into the stack then use a pump to get the waste up to that higher level).

EDIT If none of the above are possible then it would be worth trying a pump- rather than having a highish pressure one that can shift the sudden volumes emitted by washer/sink you would do better with a sump (50 litres or so) and a low pressure pump (high pressure and pushfit waste are not going to combine well). Since you're on grey water a fairly cheap submersible would be worth a go, going to be cheaper than ripping the kitchen out. If that works then you'd need some careful bodgery to stop the sump stinking after a few days but that bridge can be crossed if you get to it.

 

[RonSwanson]

The stacks are internal to the house with no visible signs of them or drains on the outside.

I've drawn up a diagram of the layout - more detail than requested but useful anyway. I think the ideal route would have been to go under the dining room, as long as both the sink and stack were in between the space between joists (I can't tell). Regardless, the dining room had a wooden floor laid at the same time as the kitchen so also can't be lifted without significant expense.

The only accessible space under floor is under the utility room and on the right-side of the kitchen.

 

[oldbutnotdead]

That's a very posh sketch. And very helpful for looking at options. From your description and the sketch the problem bit is the 4.5 metres under the utility room (assuming the kitchen sink drains properly).
First (low cost but high pain in the bum job)- if you can get under the utility room floor, do so and check that pipe for sags- think someone else mentioned it, good odds it isn't clipped adequately so there'll be a low point causing an airlock causing your problems. If that is the case there are ways to clip it without having to access the full length (long bit of 3 x 2 with gutter clips prefixed slid under the floor and fixed at both ends would work, there are all sorts of bodges available, really depends how long a bit of stick you can thread under that floor)
Second option- if you can get access to the outside of the wall to the right of the utility room/bottom of the kitchen- could be a pump (cheapest way would be a 25 litre tank under the sink in the utility room with a submersible pump and float switch)- output via hosepipe going up to the utility room ceiling then (using your sketch orientation), east across and through the outside wall then south to the corner then west outside the kitchen wall then finally north into the stack pipe. There would be issues with stagnant water which would need addressing but don't worry about them yet.
Third option (being realistic) is to live with it until the next kitchen/dining room refit (usually mandated by the other half) and put in proper sized pipework.

 

[RonSwanson]

I've been down before to check the 4.5m length for sags. It was sagging in places so I added supports but it didn't really help. The pipe's obviously been like that for a while and has warped to that shape but I managed to get it more or less straight. The drop on the 4.5m length isn't great, but I think the problem might be where it turns. I'm not convinced that the drop from the turn to the kitchen sink is very good and it might sag a little too (I can only see it from the end through a narrow gap, so not a great view). If I was to raise it at the turn, it would make the drop from the utility room sink worse, so it's a catch 22. The only real way to fix it under floor would be to drill holes in the joists that it crosses, to allow a more gradual slope and that sounds like a bad idea.

I think, as you say, I might just have to live with it for now.

Thanks for your input