Bathtub drain smell and flies

Hello everyone, this is my first post on here. I became a new homeowner about a year ago.

We have a large jetted tub in our master bath that has been a thorn in our side the past few months. We noticed that the tub (specifically the drain) elicits a very musty order that is noticeable some days and not others. When we started seeing drain flies around the bathroom, we suspected the drain as the source. We have run baking soda/vinegar/hot water through it a couple times over the past 6 months when the smell has gotten bad. But the smell always seems to return.

After the latest baking soda/vinegar cleanse about a month or two ago, we taped the drain opening shut with duct tape, and yesterday we removed the tape and noticed about a dozen dead flies stuck to it and a couple more flew out (so there is still some active breeding I'm assuming). I tried the Drano foaming stuff and the drain still smells (especially when pouring the hot water into the drain, when the smell is strongest). I'm assuming there is probably some bacteria gunk caked to the pipes that is causing the smell/fly activity. My wife is repulsed and won't even go in the bathroom at this point.

The house is 20 years old and we've only used the tub twice since we got the house (stopped using it after we knew of problem). But the smell/flies seem to keep coming even though we are not using the tub. I don't know if previous owners ever cleaned it or how much they used it.

At this point I am looking to see if anyone has other suggestions for what we could do to help remedy the smell and flies? Should we keep trying with baking soda or Drano but do it more frequently? Do I need to have it snaked somehow (I don't own a snake and not sure what tool I would need). Should we call a pro? Thanks!

 

I've had good luck with Drainbo treatment for drain flies. It takes a while to work, but it breaks down the sludge and organic matter that attract the flies. In the short term, you can pour a quart or two of boiling water down the drain; that might help.

Jetted tubs should be cleaned periodically with jetted tub or spa cleaner. You fill the tub, add the cleaner, and then activate the jets so the solution is circulated through the pipes, pump and jets.

You need to do this periodically even if you are not using the jetted system as the pipes retain water and you will get growth in them if not cleaned.