How to Replace a Toilet Fill Valve in 8 Simple Steps

If your toilet won’t stop running, it’s likely time to replace the fill valve

A view of a toilet in a bathroom
Photo: Pixel-Shot / Adobe Stock
A view of a toilet in a bathroom
Photo: Pixel-Shot / Adobe Stock
SKILL LEVEL
Simple
COMPLETION TIME
1 hour
COST
Up to $25
Get quotes from up to 3 pros!
Enter a zip below and get matched to top-rated pros near you.
Geo Icon
What you'll need:
TOOLS
  • Wrench or channel lock pliers
  • Second set of pliers (if needed)
  • Turkey baster, sponge, or towels
SUPPLIES
  • Toilet fill valve

Your toilet’s fill valve is responsible for the flow of fresh water into your toilet tank. It opens and closes with every flush, inevitably wearing out over time, so most homeowners will have to replace a toilet fill valve here and there. Luckily, it’s a pretty simple fix and you can do it with basic tools and an inexpensive replacement part. Here’s a quick step-by-step for replacing a toilet fill valve.

How to Change a Toilet Fill Valve: What to Know Before You Start

If you’re hearing running water in your toilet, you should first ensure that the fill valve is the culprit. Replacing the fill valve isn’t the only method for fixing a running toilet: If you’re hearing constant running water, you may need to look up how to replace a toilet flush valve instead. Or, if you’re hearing a ghost flushing noise, you may need to clean or find out how to replace the toilet flapper

To determine whether the fill valve or the flush valve is at fault, place a few drops of food coloring into your toilet tank and wait about an hour. If the dyed water doesn’t move into the bowl, it’s most likely the fill valve that’s causing the running water sound.

  1. Shut Off The Water Supply

    Always shut off the water supply before performing work on your toilet. There should be a water valve just below the toilet tank, between where the pipe comes out of the wall and where it connects to the toilet tank. Typically, you’ll turn the valve clockwise until it stops moving to shut it off.

  2. Drain the Toilet Tank

    After you’ve shut the water off, remove the tank lid and hold the flusher down to drain as much water as possible. Then, use a turkey baster to suck up the remaining water. You can also use a sponge or some towels to do this. Or, if you have a wet-dry vacuum, it will make quick work of the task.

  3. Find the Fill Valve

    A view inside a toilet tank with a toilet fill valve
    Photo: Lost_in_the_Midwest / Adobe Stock

    Your toilet’s fill valve is typically off to one side and has a tube attached that connects to the overflow pipe. In older toilets, the float connects to the top of the fill valve. For newer models, it is the plastic column that includes the float.

  4. Remove the Old Fill Valve

    Locate the nut that attaches the fill valve to the water supply line on the outside bottom of the tank. Loosen it by using a wrench or channel lock pliers and turning it counterclockwise. To prevent rotating, you may need to use a second set of pliers to grab the bottom of the fill valve from inside the tank.

  5. Add the Rubber Washer to the New Fill Valve

    Your new fill valve should include a rubber washer to prevent leaks from the base of the fill valve. Slide this onto the bottom flange of the fill valve’s tailpiece (the skinny end).

  6. Adjust the Fill Valve’s Height, If Needed

    If necessary, adjust the height of your new fill valve so that it’s taller than the overflow tube but still short enough to allow the tank lid to close. See your manufacturer’s instructions for doing this, as different models have different methods.

  7. Install the New Fill Valve

    Insert the new fill valve into place with the rubber washer at the bottom. Then, using your fingers, carefully tighten the fill valve nut connecting the supply line at the outside bottom of the tank. Do not use pliers and be careful not to overtighten, as this can crack the toilet tank or the valve.

  8. Turn on the Water Supply

    A view of someone flushing a toilet
    Photo: titikul_b / Adobe Stock

    Once everything is in place, turn your water supply back on and allow the tank to refill. Then, give it a test flush to ensure everything’s in working order. 

Replacing a Fill Valve on a Toilet: DIY vs. Hiring a Pro

If you’re not up for the DIY, or if you’re not sure the fill valve is at fault, you can always turn to an expert for help. Toilet repairs cost $240 on average, but fixing a fill valve can cost as little as $50. A local plumber will be happy to go over costs with you and can quickly get to the bottom of your toilet’s constant running. 

Additional Questions

Are all fill valves for toilets the same?

Toilet fill valves come in several different varieties depending on the age and model of your toilet. If your toilet has an older type of fill valve, you may want to use this opportunity to replace it with a more modern and efficient valve.

Can you fix a fill valve on a toilet?

In most cases, the best course of action is to replace the fill valve entirely. However, some models may be repairable, so review your manufacturer’s guidelines to be sure.

Need professional help with your project?
Get quotes from top-rated pros.
The homeowners guide to Plumbers
From average costs to expert advice, get all the answers you need to get your job done.
A contemporary bathroom with granite tiles and a shower
Aug 21, 2024
Aug 21, 2024
Wondering how much shower valve replacement costs? The answer is about $315 on average—but foresight and research can save you some money.
Renovated bathroom with white tile
Aug 21, 2024
Aug 21, 2024
When calculating the cost to replace a shower cartridge, you need to consider the materials and labor needed and compare it to the cost of hiring a plumber vs. DIYing. This guide will help you determine the true cost of cartridge replacement.
a vintage style bathroom with bathtub, sink, and large windows
Aug 21, 2024
Aug 21, 2024
Worried about water leaking around your toilet? You may have a faulty toilet flange. Learn more about the cost to replace a toilet flange in our guide.
Woman adjusting temperature on a radiator
Sep 16, 2024
Sep 16, 2024
Two of the most common types of radiators are steam and hot water radiators. Learn how to identify different types of radiators and their pros and cons.
The exterior of a house covered in snow
Aug 23, 2024
Aug 23, 2024
Worried about frozen pipe bursts during low temps? We’ll cover how to know if a pipe has burst, plus what to do and who to call.
Low water pressure
Jan 12, 2024
Jan 12, 2024
Is your water pressure low in your house suddenly? Use this handy guide to learn about common causes of low water pressure and how to fix it.
Share project details to get started.