Anonymous wrote:If it rains and our humidifier is not on, the basement will smell musty. As soon as I turn on the humidifier, the smell goes away.

Could that be your issue?

Also run water in the drain down there and make sure your toilet is properly connected and not leaking gaseous odors.

do you mean de-humidifier?

Anonymous wrote:Check the crock for the sump pump, there’s a bacteria that feeds on iron (or something in dirt) that makes a sulfur/gassy smell, happens at our place this time every year. Some bleach based bathroom cleaner sprayed all around the interior of the pit takes care of it till next year.

Yep.

We moved into a house in the Wolf Trap area this spring that is on well water. The water is full of that iron eating bacteria. My whole house, but especially the basement, has a bad musty old house smell. I hadn't figured out what to do.

I'll try what you suggested today, and report back.

(not OP)

Anonymous wrote:np here. So if you never find the dead mouse, does the smell go away eventually?

Yes. Something died in our wall, and the smell eventually went away. Ah, home ownership is so fun!!

If it rains and our humidifier is not on, the basement will smell musty. As soon as I turn on the humidifier, the smell goes away.

Could that be your issue?

Also run water in the drain down there and make sure your toilet is properly connected and not leaking gaseous odors.

Check the crock for the sump pump, there’s a bacteria that feeds on iron (or something in dirt) that makes a sulfur/gassy smell, happens at our place this time every year. Some bleach based bathroom cleaner sprayed all around the interior of the pit takes care of it till next year.

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:OP here - my husband just reminded me that we recently got a humidifier installed in our basement. Could that be it?

I think this is probably a misunderstanding.

Whoops I misstated it. It’s a humidifier attached to an HVAC system installed in a basement furnace room.

Have you had an HVAC company check the humidifier? Could have mold/mildew.

I am surprised you have an HVAC humidifier if you live in the DC area as it's not dry here.

We have one because in winter the humidity gets to 30% and that's too dry. It uses HOT water to prevent mold.
We use a dehumidifier in summer.

Op if you can turn off all the lights and darken the basement you can use a blacklight flashlight and see where things were spilled.

Anonymous wrote:

Anonymous wrote:Another long shot since you said someone was living there with children- maybe some sort of spill or pee in the carpet?

Cat pee is the worst.

That's more of an ammonia smell whereas this situation is musty. I think the lead contender at this stage is the HVAC humidifier. May have mildew and need to be sanitized.

OP, please keep us posted.

Anonymous wrote:Another long shot since you said someone was living there with children- maybe some sort of spill or pee in the carpet?

Cat pee is the worst.