Hoping someone can advice how to tackle this mystery problem.

We have had sewage smell issues in the house from last 3 summers now. The sewage smell only comes on hot ( mostly when temp is around 90F or above) and humid days. The smell is very sporadic and originates in any bathroom of the house, it then seem to spreads in most of the bathrooms but not always in all. Some parts of the house also start smelling probably because of Air circulation. The smell is mostly strongest in the basement around the area where the sump pump is. There is also a bathroom right above the sump pit area. And all the plumbing of this bathroom is exposed in the sump pit ceiling.
The smell eventually desipates after 30-40 min.
We have already resealed all our toilets, no dry traps in the house.
If it is of any co-relation...We had our house remodeled 4 years back. Got a new bathroom and an ejector pump installed in the basement. However the problem started 3 summers ago.

I have been suggested different resolution by plumbers. I am lost as to which will be a most suitable option to go with. Suggested options...
1. Get a U trap for the whole house on the main sewage line.
2. Get a smoke test done to find any cracked vent.
3. Extend the length of the bathroom vent pipes on the roof and put a 90 angle bracket.

Any kind of help and advice which route to go with will be highly appreciated.

Are there any AAV used in the house? Check those for possible malfunction and letting air out.

Only when it's hot? Or only when air conditioning is on? Is the condensate discharge line connected to the sewers and it has no trap?

Wait for the pros to chime in.

No AVV valves int he house.
Only happens on hot humid summer days.
Winter, fall, spring all good.. no smell of any kind.

The AC condesnsation line directly goes in the sump pit.

Our AC was busted for a few days. we still got the smell.



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easiest way to start is a peppermint test.

copied from the internet..

Access the drain-waste-vent pipe on your roof. Pour 2 ounces of peppermint oil into the pipe, followed by 10 quarts of hot water. Cap the vent pipe.
Remain outside for the duration of the peppermint oil test once you've poured the oil and water into the vent. The person who pours the peppermint carries the smell on his hands or clothes and won't be able to properly detect the smell if it manifests inside the home.
Send a friend or family member inside the home. Instruct him to seek out the scent of peppermint and make a note of any location where he notices this distinct odor.

if this test is inconclusive then a smoke test is the next step.
do not go adding/subtracting fittings to the piping system until you know conclusively what/where the smell is coming from.



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Any chance it's not even plumbing related?

A dead animal somewhere, rots and decays, smells worse on hot & humid days. Could be behind walls, in the attic, down in the crawlspace...

I had a dead duck once, the rotten smell, smells exactly like sewer gas.

I wonder how effective the smoke test is? Curious ... If there is a cracked pipe or an open joint behind the dry wall ... how will one find the exact loction? Where will the smoke come out from?

How does one find out if there is a dead animal?
will the the rotting smell will be there for 3 years?

Dead animal smells typically last days-weeks, not years.

The peppermint test advocated by Packy works. The warning about needing help is important: I poured the peppermint and was completely engulfed in the smell. You need an assistant with a good nose to hunt around inside.

Would you advice peppermint oil test over smoke test?

peppermint oil is available at most drug stores etc.
if you can get up on the roof without great danger then this is the simplest, easiest test to perform.
no special equipment needed.
a smoke test requires special equipment and will be much more expensive.
that's why i said start with peppermint and if that test is inadequate then go for the more expensive route.

[www.google.com]

I just spoke to plumber. listening to the entire episode, he suggests to extend the vent pipes by 3 feet. He feels there is venturi effect across the roof top. Any has any experience with this?

Yes.

Usually on commercial buildings with a parapet wall around the roof.

Usually extend sewer vent pipes above top of parapet.

Some residential houses with funky roof lines.

I have no first hand experience with these items but have seen them installed on some vent pipes.....

[odorhog.com]

if the smell originates in the bathroom as you stated then you must address why.
cracked pipe?
trap syphoning?
toilet seal?
blocked vent (very rare)?

as i said before, figure out where/why before adding or subtracting anything .

a properly vented trap is immune to the venturi effect.

??? sump pump or ejector pump ???

if (sewage) ejector pump check the integrity of the pit cover seal(s)

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Thank you to everyone who responded to this post. Specially to Packy for insisting on figuring out the cause of the problem.

It was a broken wax seal of one of the toilets which was causing the problem. This toilet was above the sump pit area so the max smell was always in the sump pit area. The AC units were picking the smell and distributing it in the house. Since the bathrooms don’t have any returns...so the smell was felt the strongest in all the bathrooms making it difficult to figure out which bathroom was the actual culprit. Once the problem toilet was isolated the solution was super simple.



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the bathrooms should NOT have returns

the bathrooms, however, are required to be VENTED by code

either:

a powered exhaust fan to outside

or

an open window


This is actually termed a 'local vent' in the plumbing code.

"A vent on the fixture side of the trap."

A vent (to outside atmosphere) on the fixture side (room side) of the trap.


@hj
This 'fine point' is how the plumbers union got the 'trim' in the bathrooms - they traded the carpenters the window for the other trim.

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



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