My problem is I am getting a very bad septic smell from my downstairs bathroom.My investigating has determined that the trap is not staying full of water.My question is does the plumbing vent belong before the trap or should it be after the trap.My sinks in both our bathrooms do not vent before the trap and I do not get smells from those or any other drains in the house.
All help appreciated
Yours smelly big fig:eek:

Dear smelly big fig, why don't you follow the rule of thumb with the other drains that you don't get a smell from. Would this be a big undertaking should you corrrect it ?

I will probably get shot down from some of our experts, but I couldn't resist your sign off name so that's why I answered. :)

I have been considering this but am not sure if this will vacumn lock the drain.Also worried that this may cause other drain problems through out the house.Thanks for your response any ideas from all would be great!
Big fig out:cool:

Most likely you vent line is blocked and need to be snaked. When the line is not getting its vent air your trap seal will be siphoned out.

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My question is does the plumbing vent belong before the trap or should it be after the trap.

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The vent should install downstream,(after) from the trap. If you have one installed before the trap tyen you have a unvented fixture and the suction caused by the drainage could very well lower the trap seal to the point of allowing sewer gas to escape. Regards, Tom