Why Won’t My Toilet Flush? 6 Causes and Solutions

A toilet that won’t flush can be incredibly frustrating. Not only is it unpleasant, but it can also become a health hazard if not addressed quickly. Here we’ll explore the six most common reasons a toilet won’t flush properly and provide solutions to get it functioning again.

Clogged Toilet

A clogged toilet is often the culprit when a toilet won’t flush. There are a few key causes of toilet clogs:

Buildup of Organic Matter

Over time, organic matter like hair, grease, and food particles can build up in toilet pipes. This material collects on the sides of pipes and hardens, eventually blocking water flow. A number of factors can cause this buildup:

  • Shedding pets like cats and dogs can contribute hair that catches in pipes.
  • Cooking grease washed down drains solidifies when it cools and sticks to pipes.
  • Food waste from the garbage disposal can accumulate.

Small clogs may be cleared with a plunger. But larger blockages usually require a drain snake to break up and remove the blockage. Preventive measures like using a drain catcher and avoiding pouring grease down drains can help reduce organic buildup.

Flushable Wipes

Although marketed as flushable, most wet wipes do not break down and can cause clogged drains. When flushed, they often get tangled and collect other debris. Over time, this adds up and totally blocks pipes.

Avoid flushing anything besides toilet paper. Trash any wipes, feminine hygiene products, and other items that should not be flushed.

Toys and Foreign Objects

Children may sometimes flush toys or other items down the toilet accidentally. And foreign objects like bottles, cups, or tools can fall into the toilet bowl and get flushed down. These items can then fully or partially block drains.

Be sure to keep bathroom cabinets locked to prevent access to toys. Retrieve any dropped items immediately before flushing to avoid issues. Use a toilet auger or drain snake to fish out and remove any obstructions.

Excessive Toilet Paper

Too much toilet paper at once can also lead to clogged drains. Large wads of paper do not break down quickly and can get stuck. This problem often occurs in public restrooms where patrons use excessive amounts of toilet paper.

Be mindful not to use too many sheets of toilet paper in one flush. Public restrooms should provide signs instructing proper paper usage and have frequent janitorial checks.

Tree Roots

In some cases, tree roots infiltrating underground sewer lines are the culprit. Roots seek water sources and can grow into pipes, eventually blocking flow. This tends to occur in older homes with cracked pipes providing root access.

Root cutting, pipe replacement, or trenchless pipe relining are potential solutions for root-caused clogs. Avoid planting trees too close to home plumbing pipes to help prevent infiltration by roots.

DIY Unclogging Solutions

Several DIY methods can be effective for clearing simple toilet clogs:

  • Plunger – A forceful, repeated plunge can dislodge blockages and get water flowing again. Be sure the plunger forms a tight seal over the drain opening.
  • Auger/Snake – Hand crank augers with long cables can break up and hook debris to remove clogs manually.
  • Baking Soda and Vinegar – Baking soda followed by vinegar creates a fizzing chemical reaction that may dissolve some clogs. Allow time to work.
  • Hot Water – Boiling water poured from a kettle can melt grease blockages. Allow drain to cool before flushing waste.

For severe clogs that do not respond to DIY methods, call a professional plumber. Powerful drain machines are required to clear substantial blockages.

Leaky Flapper Valve

The flapper valve at the bottom of the toilet tank is a common source of flushing problems. This rubber seal prevents tank water from flowing into the bowl until the flush handle is pressed. If the flapper valve is compromised, it will leak and fail to seal off the tank properly. As a result, water will continuously flow into the bowl rather than filling the tank. This prevents adequate pressure and volume to flush waste.

Signs of a Leaky Flapper

  • Running toilet that will not shut off
  • Need to jiggle handle to temporarily stop running
  • Toilet turns on/fills intermittently on its own
  • Lower water level in tank
  • Higher than normal water bills

Testing and Replacing the Flapper

First confirm it is actually the flapper leaking by putting a little food dye in the tank and seeing if the colored water seeps into the bowl. If it does, the flapper needs replacement. Turn off water supply and flush out remaining water. Pry off old flapper, clean valve seat, and install a new flapper of the correct size and shape. Adjust chain length as needed and test flush. If leaking continues, the flush valve beneath the flapper may need repair.

Problems with the Fill Valve

The fill valve in the tank controls refilling with fresh water after flushing. If this mechanism is not functioning optimally, the toilet will not fill adequately to create a siphon during flushing.

Fill Valve Not Refilling Tank

Sediment buildup, a stuck float arm, or broken valve parts can prevent the fill valve from bringing in sufficient water to refill the tank. The water level will be lower than normal. Carefully inspect valve components and clean or replace worn parts as needed.

Fill Valve Stuck Open

If the fill valve does not shut off appropriately, the tank can overfill. This again prevents the correct amount of water from remaining in the tank for an effective flush siphon. The valve may be worn out and require replacement or adjusting. Ensure the float is aligned properly and moves up and down without obstruction.

Low Water Pressure

Inadequate home water pressure either from utility issues or old pipes and fixtures can also inhibit proper tank filling. Check pressure at other faucets and contact your utility company if an overall pressure problem exists. For isolated low pressure at the toilet fill valve, check for blockages or limescale in the valve/tubing and replace any corroded fittings.

Malfunctioning Flush Handle

Problems with the flush handle mechanism can impact flushing even when other tank components are in working order. Troubleshoot these key issues:

Loose Handle

If the flush handle is loose or disconnected, it cannot appropriately lift and drop the flapper to release water. Tighten the handle if it jiggles and has worked loose. Realign or reattach any disconnected handle parts.

Chain or Lever Broken

The chain or lever connecting the flush handle to the flapper may become detached or damaged. When broken, the handle cannot engage the flapper valve. Assess if simple repairs like reattaching a chain are possible, or if replacement parts are required.

Stuck Handle

Calcium deposits can cause the flush handle to stick and not fully drop down after flushing. Apply penetrating oil and work the handle to break loose mineral deposits. Replace if the handle or tank internals appear too corroded to operate smoothly.

Weak or Damaged Flush Siphon

Problems with the siphoning mechanism in the toilet bowl can also impede flushing. Water must siphon forcefully into the rim channels to create a strong flush.

Missing or Cracked Tank Bolts

Loose bolts or cracks in the tank bowl allow water to leak rather than flushing properly. Check bolts and reseal any cracks in the tank. Replace bolts and tank parts if damage is too severe. Applying tank sealant can help.

Warped Tank or Bowl

The tank and bowl must align precisely to maintain the siphon effect. If either component is warped, the toilet cannot flush effectively. Inspect for distortion or shifting and determine if realignment is possible or if replacement is required.

Obstructed Jet Holes

Small holes in the rim, called jets, help siphon water into the bowl from the tank. Mineral deposits or debris can partially block these holes and reduce siphon strength. Use a small wire brush to clear any blockages.

Plumbing Vent Obstruction

For the toilet siphon to initiate properly, air must be able to enter the waste line as water flows down. If the plumbing vent allowing this air entry becomes blocked, siphoning action is hindered.

Check the roof and ensure any vent stacks are cleared of debris, leaves, ice, or other obstructions. A professional plumber can snake a vent stack to remove more significant blockages. Proper venting should then allow flushing to resume normally.

When to Call a Plumber for Flushing Problems

While several DIY troubleshooting methods may get your toilet flushing again, some situations require a professional:

  • Chronic, recurring clogs that you cannot clear or that quickly redevelop
  • Leaks between the tank and bowl or at the base of the toilet
  • Major cracks, shifting, or distortion of the tank or bowl
  • Inability to replace flapper valve or fill valve properly
  • Roots or other extreme blockages in drain pipes
  • Sewer line backup suggesting larger line issues
  • Multiple plumbing fixtures with flow problems indicating vent blockage

A licensed plumber has the skills, experience, and heavy-duty equipment needed to address severe clogging, structural damage, venting problems, and other complex toilet repair issues.

Frequently Asked Questions About Toilet Flushing Problems

Why does my toilet have low water in the bowl?

A low water level usually means the tank is not filling sufficiently to reach the normal line. This is often due to issues with the flapper valve leaking or fill valve not closing appropriately. It can also result from low water supply flow.

Why does my toilet tank fill up slowly?

A slow-filling tank points to low water pressure, partial blockage in the fill valve or connecting tube, or problems with the home’s incoming water supply. Inspect these areas, clear any obstructions, and contact the utility if pressure is low at all fixtures.

Why does my toilet keep running?

Continuous running or cycling on and off is most commonly caused by a leaky, worn out flapper valve that should be replaced. The fill valve could also be sticking open and may need cleaning or replacing.

Why does my toilet gurgle when flushed?

Gurgling sounds point to a blocked vent, a toilet drain blockage, or an issue with the trapway. Make sure vents are clear, try plunging the toilet, and check for clogs. If no obstructions are found, the trapway shape may need diagnosis.

Why does my toilet bowl refill slowly?

Slow bowl refilling after flushing suggests low water supply pressure. Check other fixtures to compare. Remove and clean the fill valve inlet screen if debris is limiting flow. If pressure is low throughout the home, talk to the utility company.

Why is there a delay before my toilet bowl starts to fill?

A pause before refilling begins is normal. The flush valve must close completely before the fill valve activates. But an abnormally long delay before filling could mean worn or faulty tank components need replacement.


A toilet that will not flush properly can dampen anyone’s day. But while frustrating, most flushing issues can be resolved with a little detective work to pinpoint the cause. The most common culprits include clogged drains, leaky flappers, and fill valve defects. But all toilet tank and bowl components must work in harmony for flushing to succeed. With patience and the right tools, many flushing troubles can be repaired DIY-style. Know when to call in a professional for major underlying plumbing problems. Stay calm, investigate methodically, and get your toilet flushing like a champ again.