Bad smell in bathroom

[Charlie Smith]

Hi,

I am new here but just thought i would ask some advice before going ahead trying to fix my probelm.I started getting a bad sewage type smell in my bathroom last week then noticed a patch on my downstairs ceiling directly below my toilet.This morning i cut out a patch in the ceiling and found a small grey pipe going into a larger brown one around 4inch i think.It looks like my sink and bath waste tying into my toilet waste through a rubber seal.It looks like the rubber seal is loose and toilet waste is dripping out and was nearly through the plasterboard.I ran a bath last night and the smell cleared after the bath drained so i thought it was a bit of stale water in pipes.The smell was back again this morning.The pipe then goes to a septic tank although i noticed there is no vent..should there be one?I was just wondering is the solution as simple as pushing the seal back in tight.Any advice would be appreciated thanks.
Charlie

 

[snowhead]

There should be a vent somewhere in the system.

That's not a good way of joining withing a floor on the horizontal.

 

[chris watkins]

Charlie, anybody who uses below ground drainage pipe & that type of rubber seal inside a floor void is going to have made many other mistakes, without access to the whole installation it is not going to be possible to help you other than to suggest that you get a good plumber around to have a look & quote for the work required.

 

[Charlie Smith]

Thanks for your replies.I am going to get a plumber round to go over the whole house.I was thinking it didnt look good but wanted to make sure.This isnt the first problem we have had with the plumbing and the house is only 5 years old.
thanks again Charlie.