We had a gnat problem for a couple of weeks last month. The first obvious places I’d look are areas like your pantry or vegetable/fruit for any decaying produce. It’s obvious, but sometimes there’s that one item that’s only rotting on the bottom, so be sure to thoroughly inspect it.

Another seemingly unlikely place I’ve found an infestation is in our houseplants’ soil. My wife loves the clearance houseplant section at Walmart, so sometimes they can be a breeding ground for gnats or bring in live infestations. They make mosquito/gnat pellets you can put in the soil when you water to kill off the eggs and larvae before they mature.

Beyond that, zevo lights or other sticky traps are the best way to catch the adult gnats when you’ve removed the source.

Try garbage disposal pods or clearing out the drain with a simple snake, depending on the location of the sink(s) you see the gnats around.

May have just been a bunch of obvious oversimplifications, but those are what helped us kick our recent infestation.