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 problem with multiple possible culprits. Thankfully, none of them are major concerns or expensive to correct. Follow this guide to get your slow toilet functioning quickly again. 

How to Fix a Slow-Filling Toilet 

Learning why your toilet is slow to refill is step #1 for fixing it. Consider these potential reasons and how to handle each one. 

Partially Closed Water Supply Valve 

Look behind the toilet for the water supply hose connected to the wall. You’ll find a valve connected to it, which allows 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 is attached to the top of a vertical tube device in the toilet tank, manages the flow of water into the tank. A toilet fill valve could wear out, clog or shift out of alignment after years of use, preventing the tank from filling properly. Follow these instructions to adjust, clear out or fix the fill valve: 

  • Locate the fill valve: Lift the toilet tank lid and find the fill valve inside. It’s commonly installed 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 fastened to the tube. Adjust the fill valve height if required by turning the adjustment knob (found in newer toilets) or loosening the adjustment screw with a flathead screwdriver (required for older toilets). After that, verify that the water level is approximately one inch below the top of the overflow tube. 
  • Wash the fill valve: To eliminate mineral buildup and other debris from the valve, first shut off the water behind the toilet and take off the fill cap. Then, slowly turn the water back on, cupping your hand over the valve to avoid getting sprayed. Let some water flow for a few seconds to flush out dirt. Next, scrub away mineral buildup off the fill cap. If you notice cracks or substantial wear and tear, replace the valve. 
  • Clean the valve tube: Dirt trapped in the valve tube could also be at fault. Shut off the water supply and take out the valve hardware. Afterward, run a slim wire or bottle brush into the tube. Turn back on the water supply slightly to clean away the excess residue. Re-install the valve hardware and see if the toilet fills properly. 

Waterlogged Float Ball 

The float ball in older toilet models rises with the water level, closing the fill valve when the tank has filled. If the float ball is damaged or punctured and fills with water, it prevents the tank from filling correctly. 

Take off the tank lid and peek inside. A partially sunken float ball might be waterlogged. Before running out to buy a new ball, look at the float arm it’s secured to. If the arm is pointed too low in the tank, bend it up slightly to elevate the ball’s height. 

If that fails to solve the issue, you might want to simply buy a new float ball; the average cost of this product ranges between $7-$20 in most hardware or home improvement stores. Just be aware that this is an older toilet design, so it may well be better to update the existing tank parts or replace the toilet entirely. 

Blocked Plumbing Vent 

Your home plumbing system includes vents that permit air to enter the pipes. If they end up clogged, stress may build inside of the pipes, preventing the water from flowing. This can, in turn, make your toilet slow to fill or even cause the bowl to flood. 

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 tiles. Get rid of any animal nests, deep snow or other obstructions you see to ensure your plumbing works properly. 

Leaky or Blocked Pipe 

If there’s nothing apparently 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 leak or blockage in the water line could restrict your toilet tank from filling properly. It’s best to hire a licensed plumber to handle 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 dependable toilet repair in the U.S.. We can figure out the reason why the water flow is so slow and perform a cost-effective repair. If the fixture has hit the end of its useful life span, our specialists can suggest high-efficiency toilet replacement in the U.S.. We’ll help you find the replacement model and install it for you. Rest assured that every job we perform is backed by a 100% satisfaction guarantee! To schedule a visit from us, please connect with Service Experts Heating, Air Conditioning & Plumbing today. 

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