Any drain experts?

[PCoulson]

Currently the rain drain off my flat roofed garage runs via a hopper and then runs internaly into garage floor. The pipe work goes under the floor and ends up in the inspection chamber in the garden along with the floul drainage.

Ideally i would like to connect a toilet into this. Is that likley to cause me any problems? I guess i would need an air admistance valve.

I know combined systems are frowned upon but i can change to a soakaway for the rain water without reconstructing the roof or digging up my garage floor and driveway.

[Wings]

PCoulson said:

Currently the rain drain off my flat roofed garage runs via a hopper and then runs internaly into garage floor. The pipe work goes under the floor and ends up in the inspection chamber in the garden along with the floul drainage.

Ideally i would like to connect a toilet into this. Is that likley to cause me any problems? I guess i would need an air admistance valve.

I know combined systems are frowned upon but i can change to a soakaway for the rain water without reconstructing the roof or digging up my garage floor and driveway.

I do not believe the toilet, sewage can go into the same gutter, downpipe drain, so sewage toilet waste having to be separated plumbed waste outlet.

[AlmostUseful]

You’d be proposing something like a 2 pipe system, in a 2 pipe system you can have sink waste and baths etc running into a hopper at say 1st floor level, and rainwater oipesnrunning into the same. This used to be used to allow for a small amount of rainwater to give the foul system a flush down. In this type of system the toilet waste goes into a pipe which is sealed to a height above eaves level, so no gasses are vented into habitable space.

You could connect the WC into the manhole/inspection chamber, but you couldn’t utilise the hopper system.

[PCoulson]

The toilet won't be going into the hopper (why would I want a toilet on the garage roof) but will connect where the exisiting pipe goes through the garage floor.

I'm guessing the pipe from the roof would need a trap.

[Some Gump]

PCoulson said:

The toilet won't be going into the hopper (why would I want a toilet on the garage roof)

^this...

reminds me of this...

[AlmostUseful]

PCoulson said:

The toilet won't be going into the hopper (why would I want a toilet on the garage roof) but will connect where the exisiting pipe goes through the garage floor.

I'm guessing the pipe from the roof would need a trap.

I didn’t say use the hopper, I said use the hopper system. The system is the top to the bottom, until it hits the chamber.

You can’t tap a WC into it if you use the hopper system for the rainwater off the roof because you need to vent the system appropriately, and a hopper is not a suitable method.

[PCoulson]

I was think a of putting a trap on the rainwater pipe (so it doesnt act like a soli stack) and an air admittance valve on the pipe from the toilet.

[Some Gump]