After we moved into this house I realized the drain always had standing water in it, and that it made the whole house smell like damp ickiness. It's not a sewer smell, it's just watery and a little bit moldy-laundryish.

Because of this smell, I covered up the drain with a plastic saucer.

Last week our hot water heater sprang a leak, and the water didn't go down the drain because of that plastic saucer. So the water went under the wall to soak the carpet in the bedroom. Yes, I am kicking myself. It's a bad idea to block a drain. Duh.

Now that the saucer is off, though, that smell is back. I lifted the grate and there is, of course, standing water there.

My questions: is there supposed to be water there? If so, what can I do to make it not smell? If not, what is likely the problem? The home was inspected before we bought it and the inspection says nothing about that drain.

Big thanks for any advice!

Normally when we get a complaint about foul odors originating from a floor drain it is because the water in the trap has evaporated and left the trap open but in your case the water is not evaporating.

I suspect that your floor drain is not being used so the standing water in the trap is stagnating and producing the odor.

A simple method to eliminate the problem is to pour about 1/2 gal of water down that drain once a month. That will cause the standing water to move on through the drain and leave fresh water in the trap.

After you add the water to the trap splash a couple tablespoons of laundry bleach down the drain. The bleach will mix with the standing water in the trap and kill the bacteria that causes the odor.

mineral oil is available at every drug store.

The scented stuff is 'baby oil.'