Discuss Moving Pipes Undersink for Dishwasher in the General DIY Plumbing Forum area at Plumbers Forums

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Hello

I am looking to install a slimline dishwasher (integrated) into a cupboard in my kitchen.

The depth of the dishwasher is 550mm and the depth of my cupboard is larger than this. The issue, however, is that the waste pipe which leads from the sink (next door cupboard) comes out quite a bit, decreasing the depth space within the cupboard I want to put the dishwasher in. This makes the actual depth of the cupboard (to the pipe) 510mm, so 40mm short for fitting the dishwasher.

There's quite a bit of space behind the pipe itself (and backboard of the cupboard). So I was wondering if anyone had any ideas on whether it would be feasible for me to push these pipes back closer to the wall?

My initial thought was to change the two 90 degree angle joints to 45 degree angles to reduce the depth it protrudes into the cupboard. If anyone was able to give feedback on this / let me know other ideas, that'd be amazing.

There is a support beam that runs between the two cupboards, hence the need to bring the pipes out a bit in the non-sink cupboard.

I've attached pictures of the pipe in the dishwasher cupboard I want to move back, and the cupboard it leads into (with the sink).

Any help would be much appreciated.

Thanks!
 

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Isn't there just a 20mm waste pipe from the dishwasher?
Can you not just bring that through the side of the cupboard into the sink waste area and connect it to a drain there on the upstream side of the trap.
Our traps have nipples that are suited to this, I almost sure you would have the same.
 
Isn't there just a 20mm waste pipe from the dishwasher?
Can you not just bring that through the side of the cupboard into the sink waste area and connect it to a drain there on the upstream side of the trap.
Our traps have nipples that are suited to this, I almost sure you would have the same.
The issue is that the actual dishwasher is too deep by 4cm once it reaches the white pipes shown in the picture. Therefore, I am trying to increase the depth in that cupboard by somehow making the pipes further back towards the back wall, so the dishwasher fits without poking out!
 
Tbh it’s not an easy job all the pipes have to be sunk flush in the wall
 
I was considering a pipe like the grey one attached to this to sit more flush to the wooden support. Or perhaps two of the 45 angled white ones (shown in the pictures too) to replace the 90 degree.
1000030871.jpg
 

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What do you foresee as the issues that not make it an easy job?

I was thinking I could get 2 X 45 degrees to replace the 2 X 90 degrees joints, then under the sink make them a bit deeper too to ensure they're pushed back in line... does that seem feasible?

Just working in kitchen cupboard and chasing in the waste without destroying the back as you will have to go into the block / brick wall 50mm
 
Just working in kitchen cupboard and chasing in the waste without destroying the back as you will have to go into the block / brick wall 50mm
I think I'd only need to move back 40mm. I measured and if I can move the white pipes back that much, they will only reach the front of the wooden support beam, rather than having to go into the wall etc.
 
I think I'd only need to move back 40mm. I measured and if I can move the white pipes back that much, they will only reach the front of the wooden support beam, rather than having to go into the wall etc.

Looks like it’s a clip off in the second and third picture?
 
Is this the two 90 degree angle joints you're referring to that I want to push deeper into the cupboard?

Where’s the dishwasher going in the cupboard with the 90s and metal plate or the next cupboard to the right ?
 
The dishwasher is going in the cupboard with the metal plate and 90s, not the undersink one. Therefore, I want to push the pipes deeper in this cupboard (appreciate the undersink cupboard pipes will have to go back too subsequently).

Is it the full cupboard width the dishwasher?
 
Is it the full cupboard width the dishwasher?
The dishwasher will fit width wide and height wise. Width wise, there's 10-20mm wiggle room. The only issue really is the depth of 40mm due to the protruding pipes. If they could go back (which there is room for before they get close to the wall) then it will fit! Just wondering how to go about that...
 
Does your chosen dishwasher have a service void at the bottom across the rear? Some do, some don't.
Just wondered if by chance your waste pipe eventually descends to floor level, whether you could run it low down?
 
Does your chosen dishwasher have a service void at the bottom across the rear? Some do, some don't.
Just wondered if by chance your waste pipe eventually descends to floor level, whether you could run it low down?
I'm unsure about this, as I haven't bought it yet unless I can ensure it fits!

So, you're saying that with some models, there might be a void in the rear of the dishwasher low down that the white waste pipes I want to be shallower could potentially fit into, without the need to do much other than make them lower?

Having looked at a diagram, it does appear to have a void low down on the rear (picture attached). However, I think this would be lower than where it eventually goes out the wall. Therefore, I am assuming that this wouldn't work, as presumably (I am guessing) you would want the pipes running in a general downwards direction from the sink to their final destination, whilst this would be lower than where it goes into the wall?
 

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So, you're saying that with some models, there might be a void in the rear of the dishwasher low down that the white waste pipes I want to be shallower could potentially fit into, without the need to do much other than make them lower?
Yes, the bottom back of the machine is recessed a little, much like the front is for the plinth. I guess primarily for the water and waste pipes from the machine, but you could have your 4cm there?
But if you can't get the far end of the waste down to floor level, with enough fall, this is a non-starter!
Example:
IMG_0539.jpeg
 
Yes, the bottom back of the machine is recessed a little, much like the front is for the plinth. I guess primarily for the water and waste pipes from the machine, but you could have your 4cm there?
But if you can't get the far end of the waste down to floor level, with enough fall, this is a non-starter!
Example:
View attachment 94291
Perfect, thanks for this.

Having looked at a diagram, it does appear to have a void low down on the rear (picture attached). However, I think this would be lower than where it eventually goes out the wall. Therefore, I am assuming that this wouldn't work, as presumably (I am guessing) you would want the pipes running in a general downwards direction from the sink to their final destination, whilst this would be lower than where it goes into the wall?

Also, do you have any views on what the wooden beam actually does at the back and whether I could cut into this a bit?
 
Perfect, thanks for this.

Having looked at a diagram, it does appear to have a void low down on the rear (picture attached). However, I think this would be lower than where it eventually goes out the wall. Therefore, I am assuming that this wouldn't work, as presumably (I am guessing) you would want the pipes running in a general downwards direction from the sink to their final destination,
Correct
Also, do you have any views on what the wooden beam actually does at the back and whether I could cut into this a bit?
You would need to establish it's not a vital load bearing support for something above, which might involve some investigation. Don't cut it without knowing why it's there!
Could you establish if it's just part of studwork supporting the kitchen wall (eg plasterboard). Does that beam carry on up above the cabinets - can you see it?
It does look as if you could gain your 4cm without having to cut very much into it, as long as you didn't have to accommodate that solvent pipe joint as well!
 
Correct

You would need to establish it's not a vital load bearing support for something above, which might involve some investigation. Don't cut it without knowing why it's there!
Could you establish if it's just part of studwork supporting the kitchen wall (eg plasterboard). Does that beam carry on up above the cabinets - can you see it?
It does look as if you could gain your 4cm without having to cut very much into it, as long as you didn't have to accommodate that solvent pipe joint as well!
Thanks again for the reply. I've had a plumber come over to estimate the cost if I feel this is not something I'm able to do.

They've suggested that they could push it back with two well-angled 45's, or perhaps one 45 and one conversion bend 45 (but which apparently had less angle wiggle room). They said they don't think they'd even need to go into the wood and that it would clear the copper pipe.

In terms of considering whether to do this myself or not, would the two 45's be the ones in the picture attached - and if so, how would they attach together as the ends appear to be the same size?

They've also said I'd probably want 2 X new traps (one with a spigot), as well as a dishwasher T-joint on the copper pipe (picture attached).
 
In terms of considering whether to do this myself or not, would the two 45's be the ones in the picture attached
Possibly, but can't confirm that's what your plumber was thinking. That sort of thing perhaps with the first elbow mostly in the left hand cupboard, but there's a coupling where you might want to put it, so the existing T etc will probably be scrapped and re-done to suit the offset required.
and if so, how would they attach together as the ends appear to be the same size?
With a short piece of pipe!

You will need two spigots altogether. You could replace the single one on the right with a twin one (see pic below), but there's not much room for the pipes and coupling the hoses.

What with needing to add a valve to the copper pipe (don't use a ghastly DIY screw on the pipe gizmo please!), and unforgiving solvent weld fittings (which are the best to use, but in my limited experience you need to be sure the whole assembly is right before you start with the adhesive!), coupled with not a lot of room to work, I'd be inclined to leave it to a plumber if you get a fair quote!

IMG_0543.jpeg
 
Possibly, but can't confirm that's what your plumber was thinking. That sort of thing perhaps with the first elbow mostly in the left hand cupboard, but there's a coupling where you might want to put it, so the existing T etc will probably be scrapped and re-done to suit the offset required.

With a short piece of pipe!

You will need two spigots altogether. You could replace the single one on the right with a twin one (see pic below), but there's not much room for the pipes and coupling the hoses.

What with needing to add a valve to the copper pipe (don't use a ghastly DIY screw on the pipe gizmo please!), and unforgiving solvent weld fittings (which are the best to use, but in my limited experience you need to be sure the whole assembly is right before you start with the adhesive!), coupled with not a lot of room to work, I'd be inclined to leave it to a plumber if you get a fair quote!

View attachment 94293
Ahh yeah, fair enough - thanks for your help with this.

One thing I did wonder was around the washing machine tee valve. I'm planning on getting one, as shown in the picture.

Would this replace the valve currently on the cold water pipe (the one without the black lever), or would I need to cut the pipe and add it as an addition further up?
 

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Ahh yeah, fair enough - thanks for your help with this.

One thing I did wonder was around the washing machine tee valve. I'm planning on getting one, as shown in the picture.
That's fine.
Would this replace the valve currently on the cold water pipe (the one without the black lever), or would I need to cut the pipe and add it as an addition further up?
The latter. The black one is presumably the hot?? And the one on the right with the slot (which seems to be about 80% closed) is the cold? I'm guessing they are to allow the taps to be serviced without having to turn the water off for the whole house.
Cut whichever is the cold feed in a place convenient for the dishwasher hose, and where it will reach!

The valve on the right looks of some age, and in my experience, when old they can leak after you operate them. Let's hope that's the hot then!
Do you know why the right valve is largely shut - is that an attempt to reduce the flow because the hot and cold pressures are different? (If so a better way is to use a pressure reducing valve)
 
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