Sewers

What stops sewer gas form entering the home?

We have been having sewer gas come into the house . We do not have a basement but we have a building where a floor drain is connected to the house drains. I am not sure where itis coming from but I do smell it coming from the air/heating vents. Any suggestions why we are having this problem and how can it be fixed?

Public Comments

1. Sewer gas is kept from entering the home by the trap that is in the drain line. The trap has water "trapped" in it forming a barrier between the sewer gases and your home.
2. To make sure that the trap on your drains are not the culprit, simply sniff the air directly above a drain to see if sewer gas is present. Sewer gas is prevented from coming into homes by using 'traps', or special pipes that hold a small amount of standing water in them to seal the drains from the sewer. If you find no hint of sewer gas at your drains, I would suspect the Heat and air system, or hvac. Since you think it is coming from your HVAC system I would guess that you may have a mold or mildew problem caused by excessive moisture. Some of these can smell somewhat like sewer gas, and can be a bigger problem if not dealt with properly. The problem can be in the plenum, duct work or evaporator area of your system. I would call a licensed HVAC professional to locate the problem and give you recommendations based on what he finds in your particular case.
3. P-traps-- make sure the drains you hardly ever use have water in them by dumping a bucket of water in each drain. If it's not the traps then it could be a leak underground that is just permeating the house
4. probably out side air, put a cover over the drain where the building is
5. do you have a sink/bath or shower in the house that is a long way from the wall it goes through to the drain, if so it may be that the long run of the plastic pipe is sagging in the middle so water remains in there after the plug has been pulled. Caused by the hot water running through the pipe. Pull up the floor boards and check the run of the pipe and chock it up where it's required
6. Every drain to the sewer should have a 'U' bend which is filled with water and prevents the gases venting back into the house, even the bath and shower will have these, although they will be shallow traps. You are going to have to inspect every outlet and try to eliminate them. If the house is fairly new I would expect to find something wrong with a later addition - like a bodged up washing machine connection. I am concerned you have a smell coming from the heating vents as this can be possibly a serious health risk. I think you need an expert in to identify the smell - hydrogen sulphide- methane- carbon monoxide etc and this will narrow the search. I have hired gas detectors in the past from specialist construction hire companies. You may even have a dead anilmal de-composing in the air duct
7. Keep water in your floor drain. It has a trap and that will stop it.