Thread: Sewer smell at laundry

During a 1 year warranty inspection today the owner said she has on about three occasions had a strong sewer smell when she turns on the closthes washer. Key here is turns it on, not when it is draining.

Home has no roof penetrations, all AAVs terminating in the attic.
Home is on a well & septic system.
Said it seems like it happens after not using the machine for a few days.
It is not the water heater as it is in use all the time and has a re-circulating system on it.

I would think if there was not a trap, it would smell much more often. I am also wondering if the well water gets a smell to it occasionally.

Any thoughts. Thanks

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Originally Posted by Frank Bombardiere

Any thoughts. Thanks

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Trap is losing it's water seal.
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Why is the question.
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That was my first thought, however, it has happened only three times in a year and she says it happens as soon as she turns on the washer.

Originally Posted by Frank Bombardiere

That was my first thought, however, it has happened only three times in a year and she says it happens as soon as she turns on the washer.

Hot or Cold water?

Best

Ron

Those new front loading washers have been having some problems with mold and odors building up around the front seal, any chance it is one of those?

It more than likely is the well. The large empty can of the tub and the initial water blowing into it acts like an airation system for well water. The limited smell that you normally may not notice is concentarted and blows in your face. Once the water runs a little the affect goes away.

The only reason I say this is it happened to a home I built with a well. It was so faint that you could barely detect the smell with the exception of the laundry room and washer start up.

Originally Posted by Frank Bombardiere

Home has no roof penetrations, all AAVs terminating in the attic.

Not allowed.

At least ONE vent is required to vent to atmosphere outdoors.

This is what could be happening:

With all vents on AAVs and no open air vent, and AAVs are design to allow air in and not out, the sudden discharge may be pressurizing the vent system just enough to force sewer gas back through a vent.

Question: By "strong sewer smell when she turns on the clothes washer. Key here is turns it on, not when it is draining" do you mean turning it on to fill with water, or when it first starts to drain but then not when draining?

If 'turning it to fill with water', then the smell may be in the water. I.e., "Home is on a well & septic system."

Originally Posted by Frank Bombardiere

During a 1 year warranty inspection today the owner said she has on about three occasions had a strong sewer smell

Any thoughts. Thanks

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More usage than normal ( family gatherings ) that is over loading the septic system with gases bubbling back through the trap, ( more noticeable in a confined space ) with the action of the washer water displacing the gas from the washer ( if it is front load ) into the laundry room.
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Thanks for all the ideas. I believe it something to do with the well water as I just spoke to her again and she said NOT when draining but when it starts to fill. Also it is a top loader not front loader.

Jerry, Thanks for the info on DWV, I did not know that.

WAG...the washing machine is not draining completely or it may be the water left in the drain hose seeping back past the pump into the tub. After a few days that stagnant water becomes its own little microbial world. The first inrush of new water stirs that up and releases the gases.

If its an older machine its probably not worth fixing and time for a new one. Might also be time to have the well water checked.

What Richard said; There's probably some lint build-up in the pump and that smells real nasty.

Some washers have a clean-out located near the pump; get out the owners manual.

Does the water system have a filter system on it?

It may be the washing machine is not tied in with the filter system and she is getting the smell from the water.

Frank,

In case you need it, here is the code.

From the 2006 IRC. (not the entire section on AAVs, just the applicable part) (underlining is mine)

- SECTION P3114

- - AIR ADMITTANCE VALVES
- - - P3114.7 Vent required. Within each plumbing system, a minimum of one stack vent or a vent stack shall extend outdoors to the open air.

On the subject of air AAV's this is straight out of the Texas Residential Construction Commission's handout on construction. Bold is mine.

Pipes and Vents
Water pipes shall not make excessive hammering or banging sounds.

Changes in water temperature may cause a ticking sound that is normal as a result of changing temperature in the pipes.

Sewer gas odors escape the plumbing system through vent stacks or air admittance valves that are designed to allow gas to escape.

Air admittance? Admit....escape....

And we wonder why things are so screwed up!

Vent stacks don't only allow for the plumbing system in residential and commercial buildings but it provides the cities sanitary sewer sytem a way to vent.

Originally Posted by Wayne Carlisle

On the subject of air AAV's this is straight out of the Texas Residential Construction Commission's handout on construction. Bold is mine.

Pipes and Vents
Water pipes shall not make excessive hammering or banging sounds.

Changes in water temperature may cause a ticking sound that is normal as a result of changing temperature in the pipes.

Sewer gas odors escape the plumbing system through vent stacks or air admittance valves that are designed to allow gas to escape.

Air admittance? Admit....escape....

And we wonder why things are so screwed up!

Vent stacks don't only allow for the plumbing system in residential and commercial buildings but it provides the cities sanitary sewer sytem a way to vent.

Yeah, air admittance valves are designed solely to admit air, not expel air, thus the requirement for at least one vent going to outdoor air.

Well.. while hardly being an AAV, the Studor company does make something called the Maxi-Filtra. It's a black vent that resembles an AAV, except it's got a carbon filter inside of it, to permit the air to go in AND out and to get rid of the odor while doing so.

Outdoor use only.

STUDOR (R) inVENTive Technology (TM) - Air Admittance Valves

"Contains replaceable carbon filter that can last up to two years "

Great, and who is going to replace it later?

I can see it now, home owner conversation "Honey, I think you need to stop eating beans all the time, I mean, have you noticed THAT SMELL lately? Maybe your digestive system can no longer handle those beans?" "Sure sweetheart, I'll stop eating beans if it will make you happy."

(months later)

"Honey, I thought you were going to stop eating beans? It still smells, and we are having that backyard B-B-Q this weekend."

I use them in some situations. Of course, I treat the vent as though it were any typical vent -- 10 feet away, 2 feet above -- but it does work. They give you a little sticker to slap on there with the date so you know when to replace the carbon. Though, I doubt they ever WILL get replaced.