My shower periodically has sewer smell (comes and goes). I have cleaned out the drain and snaked it - no clogs. I look down in the drain and there is clear water thus the P-trap is not dry. I have also snaked the roof vent. After doing all this I still get sewer smell in the shower periodically. May be time for a professional but is there something I am missing or overlooking? If time for professional does anyone have a recommendation for Keller area? Thanks for any feedback.

Do you live near a lake or river bottom (low elevation); or is your house located on higher ground?

Question...do you live near the sewer main where the wind could create a vacuum? I had this issue at a previous house of mine, when we would get a strong SW wind, it would create a vacuum that pushed it into our house. It didn't happen a lot, but did have a plumber tell me we could get specialized valves installed to block the back flow of pressure. Then around a year or so living there, something occurred that made the city replumb their ducts and it went away.

No - do not live near lake or river. House is same elevation as all neighboring houses. Sewer main runs out in the street. I have three bathrooms (two down and one up) and only one of the downstairs has the sewer smell and it is furthest bathroom from sewer main. Thanks

I run some of this through mine periodically and it helps.
https://www.amazon.com/enzyme-drain-cleaner/s?k=enzyme+drain+cleaner

Some times a partial clog down the line causes a toilet flush to suck the water from a p-trap.

Before you call a plumber, use some drain cleaner that dissolves hair. I have some friends that have wives with long hair and they have said the hair acts like a wick and will empty the water out of the trap.

Try to see if it’s only happening on/with certain wind directions.

Thanks for the responses all!

I have used enzyme cleaners. I have done the baking soda/vinegar cleanse numerous times. I have cleaned out the drain. Water crystal clear when look down drain into P-trap. I have snaked the drain (25 ft. long snake). I have snaked the vent. Water does not back up into the shower. Wind direction seems to have no affect. Unless there is something I am missing, only thing I can figure now is there is a leak somewhere past the P-trap (P-trap always has water so not the P-trap). If there is a leak past the P-trap, I do not know how smell is getting into shower. No wet soil outside the wall. Shower and drain is sealed. I am at a loss.

Pour a gallon of bleach in the drain and let it sit for 24 to 48 hours.

Its possible that all this work and attention on the drain is just wasting time. Can you put a rubber plug in the shower drain or something that seals it really well? If you plug it and the smell goes away, that will tell you for sure it is coming up through the drain pipe. If you still get the smell, its coming from somewhere else.

Could be as simple as a bacteria buildup on the drain and lines. As suggested by RR, use bleach.

So, just out of curiosity, how often is this shower used? How often is this bathroom used? If the bathroom is a guest bathroom that is rarely used, the smell may not be coming from the shower line. It could be coming from the toilet...Have you flushed it lately? Or even the sink, but I'd suspect the toilet first...the p-trap under the sink could be dry. I'd run water through all the fixtures every 2 weeks to just put new water in the traps.

Also, do you have gas lines running in the house?

I get that occasionally from my master bathroom sink but I have an aerobic septic system. When it happens I pour enough hydrogen peroxide in it to fill the ptrap and let it sit for awhile.