Unknown fatter waste pipe

[Robin66]

Hi DIYers. I'm in the process of my first kitchen install and have had a productive weekend gutting the kitchen. Now I need to move the sink waste across and am having trouble identifying the existing fittings.

In the lower-left of the pic below you can see the waste come up from the floor below (40mm white) then join onto a much wider grey bend, which then goes to a Tee having a ~55mm pipe going up off-pic to the sink waste. Why is the pipe going up to the sink 55mm? Can I replace this whole section with standard 40mm fittings? These fittings near the sink waste are much bulkier than the rest of the waste and I'm confused as to why.

Untitled

• Robin66
• 2 Mar 2015
• 1

 

[TeaTime]

They probably had trouble with blockages in the past and thought that increasing the waste pipe size would solve the problem.

40mm is the minimum trap size so I would have thought that connecting to the existing / running new 40mm wouldn't be an issue.

 

[Madrab]

Ive seen them using larger waste pipe when a waste disposal was installed, they have a min of 50mm, so they may have increased that. Bit silly though then running it into 40mm, kinda pointless.

If you're using a standard sink then as TT mentions, 40mm should be fine.

 

[Robin66]

Great, makes sense. thx for your help

 

[TeaTime]

Ive seen them using larger waste pipe when a waste disposal was installed, they have a min of 50mm, so they may have increased that. Bit silly though then running it into 40mm, kinda pointless.

If you're using a standard sink then as TT mentions, 40mm should be fine.

Yeah, as Madrab said, I have assumed it is just a standard sink waste now, since you haven't said otherwise.

Hope it all goes well.