My en-suite shower sometimes emits a sewer smell. This is particularly noticeable if a full sink of water is emptied or there is a strong wind outside. I think both of these cause the water in the shower trap to be sucked out, leaving no seal between the shower and the riser pipe. The shower trap is a small one, should I fit a deeper one or perhaps fit two traps?

It's illegal to double trap a fixture. Do you hear any sounds out of the shower trap when draining or flushing? Any other traps smelly? Remove the strainer and measure how much water's in the trap. Let me know, Tom

Hi Tom, thanks for info. There are no sounds from the shower trap and no other traps smell,including the sink(hand basin).
The shower trap is very small and there is hardly any water in it.I appreciate the legal point and will heed your knowledge. Once again my thanks ,Dave

Is this shower on a slab? If so we have lots of work to do. If not it's a piece of cake to replace the trap. Back to you, tom

Hi Tom, have now taken shower tray out and will be putting a new one in. It will be on a plinth so there will be room for a deeper trap, hope you can concur that will be OK ,thanks Dave

You're elevating your shower base on blocks? Was it that way before? So the shower is on a slab? Back to you. Yom

You're elevating your shower base on blocks? Was it that way before? So the shower is on a slab? Back to you. Yom

Hi Tom, yes it was on a slab and will be again, there is room to put a deeper trap in ,what I really need to know is it likely that a deeper trap will fix the issue, before final fix and tiling takes place, regards Dave

Here's what I would try first before replacing the trap. Remove the strainer andn shine a light down into the trap. Have someone flush the toilet. Does the water level in the trap bounce up and down?
Now, while the strainer's off run a snake down the drain. Tonight. Pour as halve gallon of bleach and let it set overnight. Next morning flush it out with as large pan of boiling water.
Let me know what happened with the traps water level. Good luck. Tom