The P-trap (or S-trap in older homes) under your shower is designed to prevent sewer gas from coming back up, so you shouldn’t normally experience foul odors coming from your shower drain. If you do, the vent stack that introduces air into your plumbing system may be clogged, or you may have a more severe sewer main blockage. In either case, hire a plumber to fix the issue for you.

You can unclog an AC drain line for free if you already have these household ingredients: water, vinegar, and rags. Alternatively, if you’d rather not deal with the mess, you can hire a pro to clear your drain line. If you go that route, an HVAC service call costs between $100 and $250.

If you try a drain snake and various DIY methods for unclogging drains to no avail, bring in a professional plumber to assess the situation. Also, if multiple drains in your home are backing up or you smell sewage, a visit from a plumber is best. You can expect your drain cleaning costs to fall around $250, and this can include an assessment of what’s caught in your plumbing and if there’s a larger, underlying problem. You should also consider calling a pro if you need to snake a toilet, as DIYing this could lead to a cracked fixture.

If you're dealing with a clogged sink drain, you may be able to avoid removing the drain by using a plunger to dislodge the clog. While we associate plungers with toilets, they can do the same job with your sink drain. Be gentle, though, as forceful movements can push clogs further into your plumbing system and make them more difficult to remove. Additionally, make sure you’re using a sink plunger—with a flat bottom—and not a toilet plunger—which has a smaller bottom protruding from the larger flat piece.