Why Does My Toilet Keep Clogging?

A toilet that keeps clogging usually has one of three problems: what is being flushed, a toilet that cannot push enough water, or a blockage past the toilet in the vent or the main sewer line. If other drains in the house are slow or gurgle too, the problem is the line, not the toilet.

What makes a toilet keep clogging?

Most repeat clogs come from seven causes. The first four rows are the most common and the cheapest to fix.

A small object is a common hidden cause. A toy, a comb or a toothbrush can lodge in the curve of the trap. Water still gets past it, so the toilet seems fine, but paper catches on it every few days.

Is it the toilet or the sewer line?

It is the sewer line if more than one drain is affected, and the toilet if the problem stays in that one fixture. You can check in about five minutes:

1. Flush the toilet and watch the nearest tub or shower drain. Water rising or gurgling there points to the main line.
2. Run the bathroom sink for a minute. If the toilet bubbles or its water level moves, the line past the toilet is restricted.
3. Check the other bathrooms. Slow drains in more than one room mean the main line.
4. Think about how the clog clears. If an auger clears it and it comes back within days, something is narrowing the pipe past the toilet.
5. If only this toilet clogs and every other drain runs fast, the problem is the toilet itself.

A clog in the main line is the one that can back sewage into a tub or onto the floor, so do not keep plunging if several fixtures are involved. Our guide to unclogging a toilet without a plunger covers the one-toilet case.

How do you fix a toilet that keeps clogging?

Fix the toilet first, then the habits, then look past the toilet. In order:

1. Clear it properly. Use a flange plunger, the kind with a soft sleeve that seals into the bowl. A flat cup plunger cannot seal a toilet. See which plunger fits which drain.
2. Run a toilet auger. A toilet auger reaches about 3 to 6 feet and pulls out objects a plunger only pushes deeper.
3. Check the flush. Lift the tank lid. The water should sit about an inch below the rim of the overflow tube, and the flapper chain should have a little slack. A short chain or low water makes a weak flush that leaves waste in the trap. Our guide to a toilet not flushing all the way walks through each part.
4. Change what goes down. Nothing but toilet paper and human waste.
5. Skip chemical drain cleaners. They rarely reach a clog in a toilet trap, and the next person who plunges gets splashed with them.

If the clogs continue after all five, the cause is past the toilet.

Can “flushable” wipes clog a toilet?

Yes. Wipes marked flushable still clog pipes. The North Texas Municipal Water District, which serves Plano, Frisco, McKinney, Allen and Richardson, warns homeowners that “unlike toilet paper, these stronger wipes don’t breakdown quickly. The result: wipes clogging pipes!” Its rule is to flush only the three Ps: pee, poop and paper.

Wipes rarely stop in the toilet itself. They pass the trap, then snag on roots, scale or a rough joint further down the line and build into a clog that returns every few weeks.

Should I replace an old low-flow toilet that keeps clogging?

If it was made in the 1990s and clogs with normal use, yes. The U.S. EPA says 1990s low-flow toilets “were sometimes associated with performance issues (e.g., requiring double flushing).” Newer toilets with the WaterSense label use 1.28 gallons per flush or less and, in EPA’s words, “far outperform traditional toilets from the 1980s and 1990s.”

This is the honest answer a plumber should give you. If the toilet itself is the weak link, no amount of drain cleaning will fix it, and replacing the toilet is the repair.

When is a toilet that keeps clogging a sewer line problem?

It is a sewer line problem when the clogs come back even though the toilet flushes well and nothing unusual is being flushed. In Dallas-Fort Worth the usual causes are:

• Tree roots growing into the joints of the line from the yard. See what kills sewer roots and what fixes them.
• Scale inside cast iron. Homes built before the 1980s often have cast iron drains, which scale from the inside and narrow the pipe until paper catches.
• A belly, a sag where the pipe has lost its slope and holds water and waste.

Plunging and snaking cannot fix any of these. A cable punches a hole through the blockage and the line closes again, which is why a drain keeps clogging after it gets snaked. A sewer camera inspection shows exactly what is inside the pipe, and you keep the footage.

How much does it cost to fix a toilet that keeps clogging?

It depends on where the problem is. Nuflow DFW’s starting prices:

We are not the right call for a toilet that clogs once after a heavy flush and clears with a plunger. That is a habit fix, not a service call. Call when the clogs keep coming back, when more than one drain is involved, or when the camera is the only way to see what is going on.

Call (469) 701-0597, Monday to Friday, 9 to 6, or schedule online.

FAQ

Why does my toilet clog every time I poop?

Usually a weak flush or a partial blockage in the trap. Low tank water or a short flapper chain cuts the flush short, and an object caught in the trap snags solids. If a toilet auger and a tank adjustment do not fix it, an older low-flow toilet is the likely cause.

Can a clogged vent make a toilet keep clogging?

Yes. A blocked roof vent starves the drain of air, so the flush loses force and the toilet may gurgle. A clogged main line causes the same symptoms, so rule that out first. Here is how to tell if your plumbing vent is clogged.

Will a clogged toilet unclog itself?

Sometimes, if the clog is only toilet paper, which softens in water over a few hours. Wipes, paper towels and objects do not break down, so they stay put until they are pulled out.

How do I keep my toilet from clogging?

Flush only toilet paper and waste, use less paper per flush, keep the tank adjusted for a full flush, and keep a trash can in the bathroom for everything else. If clogs still return, have the line checked.