Should toilet waste pipe have gradient from toilet to wall?

[happypeter]

Hi,
I’m about to install a new toilet and make a new hole in the wall. I can’t figure out if the new hole should be completely level with the toilet pan waste, or slightly lower to create a gradient.

When pushed against the wall the toilet waste connection is 25cm from the wall, the wall itself is 26cm thick…so 51cm until it reaches the outside waste pipe.

Where should I drill the hole? :O

many thanks!

 

[Madrab]

the ideal fall on waste pipe is around 25mm in a metre (1:40)

 

[Steady]

You can drill your hole level with the pan spigot if you want.
what happens if you put too much of a gradient on that first length of pipe from the pan is your first soil elbow outside the wall looks p***ed.So unless it’s a huge long run from the pan to the stack just drill it level and it will be fine

 

[Madrab]

If you want the pan to empty it's contents correctly then the outflow pipe connecting the spigot to the main run must have a fall on it so there is no resistance to the initial flow.
Any resistance to that outflow, after the pan bend, can allow solids to be left in the pan, especially with some new toilets with their narrow bends and reduced water flush volume.

 

[happypeter]

Thanks level it is

 

[Madrab]

Best of luck with that

 

[Steady]

assuming you are going straight out of the wall 4 inches or so behind the pan you can drill a hole level with the pan spigot -so long as you use the right size core drill (127 mm for 110mm soil ) You can then create a very slight fall from the pan connector. You don’t need to drill the hole lower than the pan spigot in these circumstances.