Stinky Laundry Room? Stinky Bathroom? Check Your Traps.

By
Home Inspector with Structure Tech Home Inspections

Have you noticed any foul odors in your basement that you just can't get to the bottom of?  It might be sewer gases coming in to your home.  Every plumbing fixture needs to be equipped with a trap, which is basically a dip in a pipe that water fills up.  This water sitting in the trap is what prevents sewer gases from coming in to your home.  The photo below shows a "P-trap" - this is the type of trap you'll find below sinks, showers, and bath tubs.

P-trap explained

Toilets have their own built in traps, and so do floor drains.  The trap on a floor drain is located below the surface of the floor - the photo below shows a floor drain as seen from the side.

Floor Drain

The problem that home inspectors often find in basements is that floor drains or other plumbing fixtures in the basement never have any water flowing to them, so the water in the trap eventually dries out and allows stinky, hazardous sewer gas to come in to the home.  Because of this, abandoned or shut off plumbing fixtures are always listed as a hazard or required repair on Truth-In-Sale of Housing evaluation reports in Minneapolis, Saint Paul, and the rest of the surrounding cities.

P-trap with no water

Floor drains are the most frequent offenders.  If a floor drain doesn't have water flowing to it on a regular basis, the water in the trap will dry out.  A few common things that regularly drain to floor drains and help prevent the traps from drying out are AC condensate drain lines, high efficiency furnace condensate drain lines, humidifier drain lines, dehumidifier drain lines, HRV drain lines, and water softener discharge lines.  If you don't have anything draining to your floor drain on a regular basic, the water in the trap may evaporate.

rv antifreeze

One fix is to pour some RV antifreeze in to the drain.  RV antifreeze is cheap, sold everywhere, safe for the environment, and it won't evaporate.  It's made just for this kind of thing.  Another option is to periodically pour some water down the drain; you'll obviously need to do this on a regular basis, but it's free and easy to do.
 
Basement toilets are another frequent offender.  These are typically found in old Minneapolis and Saint Paul homes, and it consists of a toilet sitting out in the middle of the basement, with no privacy offered.  These toilets don't get much use, and the water in the bowl eventually dries out.

If you have an abandoned toilet in your basement, have it removed and have the opening to the sewer capped off.

Abandoned standpipes can be another source of sewer gases.  A standpipe is a stand-alone trap that typically receives the discharge water from a washing machine.  If the washing machine gets moved and is not longer discharging to the standpipe, the water will eventually evaporate.

Standpipe diagram

The fix for an abandoned standpipe is to cap it off or remove it.

Infrequently used bathrooms are the final common offender.  In larger homes with guest bathrooms that never get used, the water in the sink, toilet, or tub / shower can evaporate.

As with floor drains, the fix is to pour some RV antifreeze in to the fixtures, or remember to run some water through them every few months.  Easy.

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Re-Bloggged 2 times:

Re-Blogged By Re-Blogged At
  1. Evelyn Kennedy 08/22/2012 04:17 PM
  2. Harry F. D'Elia 08/25/2012 11:37 AM
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Topic:
Home Improvement
Location:
Minnesota Hennepin County Minneapolis
Groups:
Home Inspector's Corner
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Minnesota Real Estate
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Tags:
sewer gas
dry floor drain
dry trap
purpose of trap
ptraps
ptrap
plumbing traps
stinky plumbing fixtures

Comments 32 New Comment

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Rainmaker
229,341
Reuben Saltzman
Minneapolis Home Inspections
Structure Tech Home Inspections

Margaret - if you use the shower twice a day, antifreeze isn't going to help.  Try looking down the drain with a flashlight; can you see water in there?  If not, you might not have a trap.  If that's the case, you'll be looking at a more extensive (and expensive) repair.

Charles - I think it must have been time for that plumber to retire ;)

Andrew - no thanks :)

Sandy - If you ever find pink stuff in the toilets at bank owned properties... you'll remember this.

Jay -  well, yeah... but that just goes without saying, right?  I mean, duct tape will fix anything :)

August 22, 2012 06:20 PM
Rainmaker
229,341
Reuben Saltzman
Minneapolis Home Inspections
Structure Tech Home Inspections

Donald - I'm familiar with those trap primers, but I've never actually seen one in the wild.  Have you?

Erica - me too!

Myrl - thanks.

Evelyn - glad to help, thanks!

August 22, 2012 06:22 PM
Rainer
344,044
Bill Reddington
Destin Florida Real Estate
Re/max Southern Realty

Common sense says make sure there is water in the toilet or drain. Same situation if a disposal hasn't been run in a while.

August 22, 2012 09:10 PM
Rainmaker
616,410
James Quarello
Connecticut Home Inspector
JRV Home Inspection Services, LLC

Like Don said, a trap primer. I have recommend them, but haven't seen one "in the wild". 

August 23, 2012 04:21 AM
Rainmaker
1,660,309
William Feela
Realtor, Whispering Pines Realty 651-674-5999 No.
WHISPERING PINES REALTY

This is one of the things I also tell my clients.  If it has not been used as of late, dump some water in it. The Anti-freeze is a great idea.

August 25, 2012 12:04 PM
Anonymous
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Rainmaker
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Reuben Saltzman

Minneapolis Home Inspections
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Home inspection topics in the Minneapolis / Saint Paul area.