What should the fall be for waste pipes

[morningcloud]

Hi Guys

I’ve a few questions and hope someone out there can help, all are for a domestic system not commercial.


What is the minimum and what is the preferred fall ratio for a toilet waste 110mm pipe?

I understand if its too steep solids can be left behind in the pipe, likewise if its too slight a fall.


What is the minimum and what is the preferred fall ratio for each of the following:

Basin waste 1¼" / 32mm pipe

Bath waste 1½" / 40mm pipe

Shower waste 1½" / 40mm pipe

My thanks to anyone who can help

 

[Burger]

Hi Guys

I’ve a few questions and hope someone out there can help, all are for a domestic system not commercial.


What is the minimum and what is the preferred fall ratio for a toilet waste 110mm pipe?

I understand if its too steep solids can be left behind in the pipe, likewise if its too slight a fall.


What is the minimum and what is the preferred fall ratio for each of the following:

Basin waste 1¼" / 32mm pipe

Bath waste 1½" / 40mm pipe

Shower waste 1½" / 40mm pipe

My thanks to anyone who can help

All of what you should need answers to should be in here.

Approved Document H | Part H - Drainage and Waste Disposal | Planning Portal

 

[WC1]

By the book its Basin 32 = 22mm /m (max1.7m run to stack)
Bath or shower 40 = 18 -90 mm/m max 3m to stack
It's the longer 110mm runs that fall is critical.
Deburring and smooth transition also important as fall imo

 

[ShaunCorbs]

11/4-2” 15mm a m

4” 15mm- 25mm a m depending on if your fixed by anything

 

[rpm]

By the book its Basin 32 = 22mm /m (max1.7m run to stack)
Bath or shower 40 = 18 -90 mm/m max 3m to stack
It's the longer 110mm runs that fall is critical.
Deburring and smooth transition also important as fall imo

11/4-2” 15mm a m

4” 15mm- 25mm a m depending on if your fixed by anything

Cant decide if that helps morningcloud or not.

 

[ShaunCorbs]

Mine are plumbing spec eg 1-40 and 1-110

 

[morningcloud]

Mine are plumbing spec eg 1-40 and 1-110

Hi Guys

Thank you all for your relies in particular the link CBW1982 posted.

Looking at “Diagram 3 Branch Connections” it looks as though my pipe runs are well within those limits ie. Basin 0.75 metres, Bath 2.7 metres, shower 1.8 metres and the Toilet itself 1.4 metres.