Slope of bath waste into soil stack too steep?

[denso13]

The trap seal, depth of water in the trap (not quite).

 

[Madrab]

The head o

By that you mean the highest point?

No, the head of a waste/drain etc is the furthest upstream point of a run.

 

[SJRSJR]

The trap seal, depth of water in the trap (not quite).

Thank you, that’s good to know.

No, the head of a waste/drain etc is the furthest upstream point of a run.

So where they both join the swept tee, horizontally the bath waste is about 15cm longer than the basin waste but if you add in its vertical the basin edges it.

 

[Madrab]

So where they both join the swept tee.

No - it's the furthermost point away from the soil pipe connection in any given waste run

As suggested that would be a test and see, if the bath was to be used and the bath full of water was to be let go then is there enough of a vacuum being created in that 150mm of pipe, before the basin connection, to pull the bath trap seal when it empties. When a bath, sink, basin etc is emptied, the gurgling that is sometimes heard when it finishes is air being drawn in down through the trap by the vacuum that is created by the slug of water running down the waste pipe. If the water seal is emptied enough it can then let drain smells back into the room through the trap.

 

[denso13]

So where they both join the swept tee, horizontally the bath waste is about 15cm longer than the basin waste but if you add in its vertical the basin edges it.

You can fit one on the bath and basin, just to be sure.

 

[Madrab]

I don't think I could do it with the bath, it comes with its own trap

You could always see if you can change the bath trap to an anti vac, depending on how it's configured and whether it can actually be changed

 

[SJRSJR]

So I've added 2 45 degree bends and the slope is okay, so thank you @denso13

On the subject of a rodding point. I plan to put one on the outside wall where the pipe turns towards the soil stack. I know it's meant to point downstream towards the soil stack, however that's only just over a metre (with the two bends). Inside there's a 2m run of 40mm into 50mm which will be under the floor with no access, so I'm wondering if it would make more sense to put the rodding point on that stretch. It would be pushing against the flow but it would at least be accessible if it was blocked. If the outside run got blocked I could at least take it apart. Any thoughts? Thanks.

 

[denso13]

Either way is fine, do what you prefer. Very unlikely to block in the first place.

 

[Madrab]

The usual approach would be to align the rodding point in the direction to any section that a snake wouldn't be able to easily reach from the outlet end.

In other words if there was a blockage in the basin waste run to the tee, if swept elbows are used then invariably the snake would get down the run from the basin end and be able to get round the bend to the tee. Same with the bath waste run, that would be able to get all the way down the straight run to the external bend/tee. So the only other section would be the external run to the stack but if access isn't easy and it can be disassembled then no concern there either

As suggested though, if it's all kept nice and clean (flush with a could of kettles of boiling water once a month and clean the traps/wastes every 6 months) then unlikely it will ever block.