Advice needed about smell in hallway or downstairs loo.

hi all
i have a bad smell on downstairs loo and it is starting to drive me insane so really could do with some advice.

-i think it is like a damp/stale water smell but some believe it is sewer smell. its not particulary unbearable or anything that is why i am convinced it is not sewer. to be honest cant b convinced either way!

here are the facts:

-i have replaced toilet sink and fittings.
-i have checked the vent stack outside house and it goes past roof level with no apparent blockages
-sink trap always full of water
-its one off house on biocycle unit



only other things i can think of are these, would appreciate advice:

1.-one of the plumbers that was looking into it found a small leak on the waste pipe that connect the back of the toilet to the main plastic waste pipe out to biocyle. he relaced all of this and no leak since. however, just under where the leak was, was a hole that was never cemented/filled in. im guessing alot of water leaked down here over the months. its is a gritty silty clay-ey hole. maybe i was silly, but in an effort to rid the smell (as i convinced myself it was from this hole) i cemented over it. i thought for a while the smell got a bit better but maybe that was in my head. i also note black damp speckles on the wall near the hole. So,

-could that damp hole be the source of the smell? would concrete over it not seal it?

2. i have porous travertine tiles on the floor, could wet damp and other guck seep through these and cause a smell?they were never sealed

3. could i have a cracked sewer pipe underneath the floor. would the smell permeate through concrete? i believe a peppermint test will tell me this which i am conducting tomorrow.

any other advice wud be so appreciated!

soil vent pipe should go above eaves level

if the smell persists, get a specialist company with a camera scope, place it through the drain system to check if you still have a leak

Its probably absolutely nothing to do with either of these two points but just in case I'll mention them:

Today I went to my Mother's and cleared out the drain tray at the back of her fridge/freezer above the condenser unit. As I arrived into the hall the smell similar to a sewerage one was absolutely disgusting. The smell came and went presumably something to do with the fridge reaching temperature and going on/off. If your kitchen with fridge/freezer is anywhere nearby it could be this. I followed these instructions from the manual:

11. Make sure that the special plastic container (drain tray) at the back of the appliance which collects defrost water is clean at all times. If you want to remove the tray to clean it follow the instructions below:
• Switch off at the socket outlet and pull out the mains plug.
• Push the lug down with the tip of a screw driver & pull out with a jerk movement.
• Clean the drain tray and wipe it dry.
• Reassemble, reversing the sequence and operations.



Some years ago there was a terrible smell in one of our bedrooms and it could be described as similar to a fishy or sewerage smell. When the light was turned on it got a lot worse. It turned out that the unit for the light holder needed to be replaced. I think I've read something about the bakelite is causing the problem.


Hope you find the source of the problem as they things can be extremely annoying

do you have a shower in your downstairs loo?

no shower , just toilet and sink.

Would second what Marion said about the light fitting. Had a similar problem and was blaming sinks, bathrooms, toilets but never thought it could be related to a light fitting but sure enough that was the problem. Once fitting was replaced smell was gone for good.

We had an issue with our shower drain recently. I could get a distinct sewage smell every time I stood outside the bathroom door on the landing. I tried various potions but nothing worked. Eventually I tried some (as in maybe a quarter of the pack) of soda crystals poured into the shower trap, left for a five or ten minutes, and rinsed with boiling water.

Smell disappeared.