Stop Flushing Money - Fix Your Toilet Yourself

How to Replace a Toilet Fill Valve and Stop Wasting Water

A 10-Minute DIY Fix That Can Save You Thousands

A few years back, I got a service call from a homeowner who thought he had a massive plumbing problem. The city told him his water meter showed a leak, and they assumed it was on his main water line. He was ready to spend thousands digging up his yard to replace the pipe.

Before firing up the backhoe, I asked to check inside the house first. Sure enough, the “leak” wasn’t in the yard at all—it was a faulty toilet fill valve that wouldn’t shut off. Water was constantly running into the overflow tube, down the drain, and spinning his water meter like crazy.

The fix? A part that costs just a few dollars and takes about 5–10 minutes to replace. Here’s how you can do it yourself.

Why a Bad Fill Valve Costs You Money

Your toilet’s fill valve controls how water flows into the tank after a flush. When it stops shutting off properly, it keeps sending water into the overflow tube. That means:

• Higher water bills (sometimes hundreds a year)

• False leak readings that can make the city think you have a broken main line

• Unnecessary repair costs for problems that don’t exist

What You’ll Need

• New fill valve (I recommend one with brass threads—sturdier and easier to snug up) - https://amzn.to/45TIIM6 https://amzn.to/4oX6oI1

• 1–2 pairs of pliers

• Knife or poly cutters

• Small bowl or bucket (to catch extra water)

• Towel (to protect your clothes while leaning over the tank)

Step-by-Step: Replacing Your Fill Valve

1. Prep Your Work Area

Place a towel over the toilet where you’ll be leaning. Shut off the water supply at the stop valve behind the toilet. If it doesn’t fully shut off (common on older stops), have your bowl or bucket ready to catch drips.

2. Drain the Tank

Flush and hold the handle to release as much water as possible. The less water left in the tank, the less you’ll have to catch when removing the old valve.

3. Disconnect the Water Line

Loosen the supply line nut under the tank with pliers, then finish by hand. Be ready for a small amount of water to escape.

4. Remove the Old Fill Valve

Hold the bottom nut on the valve with pliers while pressing down on the valve from above. Loosen and remove the nut completely, then lift the valve out and drain any remaining water into your bowl.

5. Set Up the New Valve

• Attach the rubber washer to the base (lip facing down toward the tank).

• Adjust the height using the threaded rod or sliding mechanism so the water line will sit just below the overflow tube.

• Brass-threaded models allow a tighter, more secure fit without over-tightening.

  
  

6. Install the New Valve

Drop the valve into the tank, making sure it doesn’t rub against the side. Thread the nut onto the underside by hand, then snug gently with pliers.

Reconnect the supply line—hand tight, then a slight snug with pliers.

7. Connect the Refill Tube

Clip the refill tube to the overflow pipe and attach it to the small outlet on the side of the fill valve. This ensures the tank refills properly after each flush.

8. Turn On the Water & Test

Slowly turn on the water supply. Wipe any moisture underneath the tank so you can easily spot leaks. Let the tank fill and check the water level—it should be just below the overflow tube. Adjust if needed.

Works for Older Styles Too

If your toilet uses the old float arm and ball setup, you can still replace it with this style of fill valve. The installation process is the same.

Why This DIY Fix is Worth It

• Saves hundreds on your water bill

• Prevents misdiagnosed “major leaks”

• Takes less than 10 minutes—even for beginners

Pro Tip: Keep a spare fill valve in your home. The moment yours fails, you’ll be able to replace it and stop water waste immediately.

If you found this helpful, check out more Wrench Warriors DIY tutorials and grab the recommended fill valve through our Amazon link—it helps us make more videos and keeps your home repairs affordable.