Why Is My Toilet Slow to Fill?

Have you noticed that your toilet is taking longer to refill after flushing? This is a common toilet issue with multiple possible causes. Thankfully, none of them are major concerns or expensive to correct. Follow this guide to get your slow toilet flowing properly again. 

How to Address a Slow-Filling Toilet 

Finding out why your toilet is slow to fill is the first step toward fixing it. Consider these potential reasons and the best way to handle each one. 

Partially Closed Water Supply Valve 

Look behind the toilet for the water supply hook-up attached to the wall. You’ll notice a valve connecting to it, which helps you to turn off the water when your toilet is being repaired or replaced. Make sure this value is open by turning it to the left. 

Problems with the Fill Valve or Tube 

The fill valve, which you’ll find close to the top of a vertical tube-shaped part in the toilet tank, regulates the water level flowing into the tank. A toilet fill valve may break down, clog or slip out of alignment after years of use, stopping the tank from filling right. Follow these tips to adjust, clear out or fix the fill valve: 

  • Find the fill valve: Remove the toilet tank lid and find the fill valve inside. It’s commonly secured on the left side with a tailpiece extending through the bottom of the tank and connecting to the supply tube and shut-off valve. 
  • Adjust the fill valve: Make sure the fill valve is secure and evenly connected to the tube. Adjust the fill valve height if required by twisting the adjustment knob (typical to newer toilets) or find a flathead screwdriver and loosen the adjustment screw (required for older toilets). Then, ensure that the water level is about one inch below the top of the overflow tube. 
  • Wash the fill valve: To take out mineral accumulation and other gunk from the valve, first shut off the water behind the toilet and remove the fill cap. After that, slowly turn the water back on, cupping your hand over the valve to avoid getting sprayed. Allow the water to flow for a few seconds to flush out dirt. Next, scrub away mineral buildup on the fill cap. If you detect cracks or significant wear and tear, replace the valve. 
  • Clean the valve tube: Dirt lodged in the valve tube could also be to blame. Turn off the water supply and remove the valve hardware. Next, run a thin wire or bottle brush down the tube. Open the water supply slightly to flush away the remaining residue. Re-install the valve hardware and confirm if the toilet fills properly. 

Waterlogged Float Ball 

The float ball in older toilet models rises with the water level, closing the fill valve once the tank is full. If the float ball is filled with water, it keeps the tank from filling correctly. 

Remove the tank lid and peek inside. A partially sunken float ball might be waterlogged. Prior to replacing the ball, check the float arm it’s attached to. If the arm is pointed too low in the tank, bend it up a little bit to raise the ball’s height. 

If that does not do the trick, you may be able to install a new float ball. Just remember that this is an older toilet design, so it may be better to update the existing tank parts or switch out the toilet completely. 

Blocked Plumbing Vent 

Your home plumbing system uses vents that allow air to enter the pipes. If they become clogged, tension may build inside of the pipes, preventing the water from flowing. This can, in turn, make your toilet fill at a snail’s pace or even cause the bowl to overrun. 

You should grab a ladder and climb up on the roof to check for clogged plumbing vents. Look for long, vertical PVC pipes poking up from the shingles. Get rid of any animal nests, deep snow or other obstructions you notice to help your plumbing work as intended. 

Leaky or Blocked Pipe 

If nothing is wrong with the water supply valve, fill valve and tube, float ball or plumbing vents, the slow toilet issue could stem from your supply pipes. A problem with the water line itself could prevent your toilet tank from filling correctly. It’s best to hire a licensed plumber to fix these issues. 

Schedule Toilet Repair with Service Experts Heating, Air Conditioning & Plumbing 

If these tips did not handle your issue, look to Service Experts Heating, Air Conditioning & Plumbing for quality toilet repair in the U.S.. We can figure out the reason why your toilet is slow to fill and perform a budget-friendly repair. If the fixture has reached the end of its useful life span, our company can propose high-efficiency toilet replacement in the U.S.. We’ll help you pick out the replacement model and install it on your behalf. You can relax knowing that every job we complete is supported by a 100% satisfaction guarantee! To schedule a visit from us, please call Service Experts Heating, Air Conditioning & Plumbing today. 

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