When should I stop DIY and call a plumber for a clog?

For a single slow sink, tub or shower, start with the simple tools. AAA's home-advice list of chemical-free strategies covers the usual order: a plunger, checking the P-trap, and a drain snake or a hooked wire. On hair and soap scum specifically, AAA says "a plunger may be all you need." Delta Faucet's guide for showers adds pulling the drain strainer with a screwdriver, cleaning it, and fishing hair out with a straightened wire hanger, with one warning: be careful "not to push any debris back down the shower drain, which will likely cause a bigger clog."

Our slow-draining sink page walks through the trap step by step. Give each method a fair try, then stop. A useful test is time, and it is a fair one: if you have made real progress in fifteen or twenty minutes, keep going. If the water level has not changed at all, it will not change on the tenth try either. Doing the same thing harder does not help, and forcing a snake past a real blockage can pack it tighter.

What you are clearing matters too. Bathroom clogs are mostly hair bound with soap, and a hooked wire or plastic strip reaches them well. Kitchen clogs are usually grease and food, and Phoenix Water Services calls grease the most frequent cause of sewer problems in the city. Grease hardens as it cools, so a kitchen clog that returns every few weeks is often coating the pipe farther down, where a household tool does not reach. For that pattern, see what not to put down the drain and the enzyme drain cleaner page.

Also decide how much of the job is safe for you. Kneeling under a sink with a bucket is fine. Opening a cleanout, working around a garbage disposal, or climbing onto a roof is not the same kind of task, and a mistake there costs more than a service call.

Any one of these is a reason to put the tools down:

• More than one fixture is slow. A shared line is partly blocked, not just one trap.
• Water shows up in a different fixture. If the tub gurgles or fills when you flush, or the shower backs up when the washer drains, read main line vs branch clog.
• Gurgling or a sewage smell. Both point past the trap, sometimes to a blocked vent. See why is my toilet gurgling.
• The clog keeps coming back. A drain that clears and then fails again in days has buildup farther down. See why the same drain keeps clogging.
• The snake hits a wall it cannot get past, or comes back with nothing while the water still will not move.
• You already poured a chemical cleaner and it did not work. Do not reach into that water. More on that next.

Here is the reasoning behind that list. Every fixture has its own short branch that joins a larger line. A clog in one branch affects one fixture. A clog in the larger line affects everything that joins it, and the water finds the lowest opening, which is why a tub or floor drain is often the first place a main line problem shows. If your symptoms follow the fixtures that share a line, the blockage is on that line, past the reach of a trap cleaning or a hand plunger.

A quick way to sort it out before you call: run each fixture one at a time and note which ones are slow, which gurgle, and which ones react when another fixture is used. That short list is worth more to a plumber than any description of how bad it looks.

Slow down, because the standing water may be corrosive. Poison Control explains that non-enzymatic drain cleaners contain acidic or alkaline chemicals, such as sulfuric and hydrochloric acids or sodium and potassium hydroxide. MedlinePlus says drain cleaners contain "very dangerous chemicals" that can harm you "if you swallow them, breathe them in (inhale), or if they come in contact with your skin and eyes."

If a product gets on your skin or in your eyes, MedlinePlus advises flushing with water for at least 15 minutes and getting medical help right away, and it warns against using vinegar or lemon juice to neutralize it. The national Poison Help line is 1-800-222-1222, and Poison Control also offers an online tool. Keep the product's container so you can read the label to the responder.

Then tell the plumber. It is a safety issue, not a scolding, because whoever opens the trap next may be splashed. Our is Drano bad for pipes page covers what these products do to pipes.

A backup in the lowest fixture in the house, like a floor drain or a shower, usually means the line that leaves the house is blocked. The EPA lists blockages among the causes of sanitary sewer overflows and says overflows can "back-up into homes, causing property damage and threatening public health." Stop using water in the house and do not keep flushing.

In Phoenix, the city says home or property owners are responsible for cleaning and maintaining the sewer line that runs from the house to the connection with the city main in the street or alley. The city names two main causes of sewer problems: grease, the most frequent, and tree roots. If the blockage might be in the city main, Phoenix Water Services lists 602-262-6691 during weekday business hours and 602-261-8000 after hours and on weekends and holidays. Our who is responsible for the sewer line in Phoenix page has the full breakdown.

A plumber finds where the blockage sits, tells you what it is, and clears it with equipment that reaches farther than a household snake. That can include a camera to see the pipe. If the same spot clogs again, the camera is how you find out why.

Have this ready when you call, and the visit goes faster:

• Which fixtures are slow or backed up, and which are fine.
• Whether anything gurgles, smells or bubbles when another fixture is used.
• What you have already tried, including any chemical cleaner and how much.
• Whether the problem is new, or has come and gone before.
• Any big changes lately, such as a remodel, new landscaping near the line, or a heavy storm.

Describe what you see and hear; that is enough. The point is to give the plumber a head start on where the blockage most likely sits, so the first tool they reach for is the right one.

HQ Plumbing & Air is licensed and insured, gives free estimates and upfront pricing, and answers 24/7. For an active backup, see when to call an emergency plumber.

If a chemical cleaner made things worse, see why is my drain worse after using Drano.