Why Is My Toilet Slow to Fill?

Is your toilet tank filling more slowly than usual? This is a common toilet problem with several possible causes. Fortunately, none of them are serious concerns or expensive to fix. Follow this guide to get your slow toilet working efficiently again. 

How to Fix a Slow-Filling Toilet 

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

Partially Closed Water Supply Valve 

Check behind the toilet for the water supply hook-up connected to the wall. You’ll see a valve attached to it, which allows you to shut off the water during toilet repairs and replacements. Check this valve to make sure it’s completely open. 

Issues with the Fill Valve or Tube 

The fill valve, which you’ll find attached to the top of a vertical tube device in the toilet tank, controls the water flow into the tank. A toilet fill valve may wear out, clog or shift out of alignment after years of use, preventing the tank from filling properly. Follow these tips to adjust, clean or fix the fill valve: 

  • Find the fill valve: Remove the toilet tank lid and find the fill valve inside. It’s usually mounted on the left side with a tailpiece extending through the bottom of the tank and attaching to the supply tube and shut-off valve. 
  • Adjust the fill valve: Make sure the fill valve is secure and evenly attached to the tube. Adjust the fill valve height if needed by turning the adjustment knob (found in newer toilets) or loosening the adjustment screw with a flathead screwdriver (required for older toilets). Then, make sure the water level is about one inch below the top of the overflow tube. 
  • Clean the fill valve: To remove mineral buildup and other gunk from the valve, first shut off the water behind the toilet and remove the fill cap. Then, slowly turn the water back on, cupping your hand over the valve to avoid getting sprayed. Let the water flow for several seconds to flush out debris. Next, scrub away mineral buildup from the fill cap. If you notice cracks or excessive wear and tear, replace the valve. 
  • Clean the valve tube: Debris lodged in the valve tube could also be to blame. Shut off the water supply and remove the valve hardware. Then, run a thin wire or bottle brush into the tube. Open the water supply slightly to flush away the remaining residue. Replace the valve hardware and check if the toilet fills faster now. 

Waterlogged Float Ball 

The float ball in older toilet models rises with the water level, sealing the fill valve once the tank has filled. If the float ball takes on water, it keeps the tank from filling efficiently. 

Remove the tank lid and look inside. A partially sunken float ball may be waterlogged. Before you replace the ball, check the float arm it’s attached to. If the arm is fixed too low in the tank, bend it up slightly to raise the ball’s height. 

If this doesn’t work, you may be able to install a new float ball. Just be aware that this is an older toilet design, so it may be better to upgrade the existing tank components or replace the toilet altogether. 

Clogged Plumbing Vent 

Your home plumbing system features vents that allow air to enter the pipes. If they become clogged, pressure may build within the pipes, preventing the water from flowing. This can, in turn, make your toilet slow to fill or even cause the bowl to overflow. 

You need to get on the roof to check for clogged plumbing vents. Look for long, vertical PVC pipes poking up from the shingles. Clear away any animal nests, deep snow or other obstructions you find to help your plumbing work as intended. 

Leaky or Blocked Pipe 

If you can’t find anything wrong with the water supply valve, fill valve and tube, float ball or plumbing vents, the slow toilet problem could stem from your supply pipes. A leak or blockage in the water line could prevent your toilet tank from filling properly. It’s best to hire a licensed plumber to tackle these issues. 

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

Is your toilet still not working right? Turn to Service Experts Heating, Air Conditioning & Plumbing for reliable toilet repair in the U.S.. We can pinpoint the reason why your toilet is slow to fill and perform a cost-effective repair. If the fixture has reached the end of its average life span, our team can recommend high-efficiency toilet replacement in the U.S.. We’ll help you decide on the replacement model and install it for you. Rest assured that every job we complete is backed by a 100% satisfaction guarantee! To schedule a visit from us, please contact Service Experts Heating, Air Conditioning & Plumbing today. 

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