Septic smell in new home

[Ryan Hampton]

I purchased a new 3bd 2bath Norris by Clayton manufactured double wide home in September 2024.

Installed:
1,000 gallon plastic tank
(3) 6ftx90ft perforated pipe and gravel leach beds **Not chambers
Distribution box with levelers
****NO GRAY WATER BED it is plumbed into the septic tank as well.

From day one in the house, when we wash clothes we have a septic smell that fills the house and outside with a strong odor. The smell is at its strongest by our 3rd load of laundry. So here’s a kicker somedays we can wash 100 loads and never smell a thing inside or out. It is my un-educated guess that the odor is determined by whatever the biometric pressure is that day. It does NOT happen when we:
Use Shower
Use the Bathtubs
Use Dishwasher
Use vanity sinks
Use kitchen sink

I’m all out of ideas on how to get rid of this awful smell, besides to just taking all gray water off of my septic system. So absolutely any help at all will be greatly appreciated! I will list below everything I’ve checked so far.

All sinks have in-line vents.
All roof vents seem to be clear.
All lines have appropriate drop all the way to the septic tank.
The clean out does not have water in it.

​

 

[MicEd69]

It could be the relatively high discharge rate from your washing machine is sucking some of the P-traps dry. Air Admittance Valves are not a good choice, IMHO. I'm assuming your washing machine is drained through a open standpipe, correct? Verify that the washing machine standpipe is properly vented. If it has an AAV, verify it is working properly and is of adequate size.

 

[Aggie83]

In my last house, our kitchen sink was vented by a 'vent loop' and we never had any problems with draining. This was a loop of pipe under the sink and the closest true 'vent' was 30 feet away.

 

[Aggie83]

And call the home manufacturer-- surely some type of warranty situation?