The best toilet fill valve for most tanks is the Fluidmaster 400H or the Korky QuietFILL Platinum 528MP. Both are adjustable-height, universal valves that fit the large majority of residential toilets, fill quietly and install in about 20 minutes with basic tools. Choose the Fluidmaster for its independent dials and long history, or the Korky for its clean install and tank height range.
Our top picks
As an Amazon Associate we earn from qualifying purchases at no extra cost to you.
Quick Comparison of Toilet Fill Valves
| Pick | Best for | Height range | Key traits | Price range |
|---|---|---|---|---|
| Fluidmaster 400H | Best overall | About 9 to 14 inches | Separate dials for tank level and bowl refill, 7-year limited warranty, 1.28 to 3.5 gpf | Low |
| Korky QuietFILL Platinum 528MP | Best quiet universal | About 8.5 to 14 inches | Ideal for toilets made since 1994 (1.6 gpf or less), adjustable height | Low |
| Korky QuietFILL 528 | Best for shorter tanks | About 7.75 to 13.5 inches | Base model, 5-year warranty, universal | Low |
| Fluidmaster 400A | Best classic replacement | Adjustable | Long-running design, simple twist adjustment | Low |
| Korky 818MP repair kit | Best combo kit | Fill valve plus 2-inch flapper | Includes 528MP valve, 100 flapper and hardware | Low to mid |
Best Overall: Fluidmaster 400H
The 400H is one of the most commonly recommended fill valves for general use. It supports toilets from 1.28 to 3.5 gallons per flush, and it has separate adjustments for tank water level and bowl refill, which helps you fine-tune to a specific toilet. Fluidmaster lists a seven-year limited warranty on it.
It suits almost any standard replacement. The trade-off is that the design depends on a refill tube clip to the overflow pipe, and a poor tube position can cause the valve to run, so spend a minute positioning it above the water line.
Best Quiet Universal: Korky QuietFILL Platinum 528MP
Korky describes the 528MP as fit for toilets made since 1994, with a height range of roughly 8.5 to 14 inches. The Platinum version is designed to fill quietly, and the adjustment is tool-free. It also pairs with the Korky 100 flapper in the 818MP kit.
It suits owners of modern toilets who want a fast, quiet fill. The trade-off is that very tall or very short tanks sit outside its range, so measure first.
Best for Shorter Tanks: Korky QuietFILL 528
The base 528 adjusts from around 7.75 inches up to 13.5 inches, which covers shorter tanks and low-profile toilets that taller valves cannot fit. It is a universal design with a five-year warranty according to the maker.
The trade-off: it lacks the Platinum extras, and in tall tanks it may not reach.
Best Classic Replacement: Fluidmaster 400A
The 400A is the long-standing Fluidmaster standard, widely stocked and straightforward to adjust by twisting the shaft. It suits anyone replacing a failed unit on a standard-sized tank. The trade-off: newer designs offer more adjustability, and it is less quiet.
Best Combo Kit: Korky 818MP
If your flapper is also old, the 818MP bundles the 528MP fill valve with a 2-inch flapper and the hardware. Replacing both parts at once saves a second trip and handles the two wear items together. Check that your toilet uses a 2-inch flush opening before you buy.
How to Choose a Fill Valve
Measure the tank
Measure from the base of the old valve (the tank bottom) to the top of the overflow tube. The fill valve must sit about 1 inch above the overflow tube when adjusted. Most universal valves cover roughly 8 to 14 inches.
Check the shank thread
Most toilets use a standard 7/8 inch tank hole and a 1/2 inch supply connection, but verify before you buy.
Valve type
Float-cup valves such as the Fluidmaster and Korky models ride along the shaft and are less likely to jam than ball-float designs. Choose a float-cup valve unless you have a very old toilet.
Water pressure and noise
Noise is usually from the valve seat or from high household pressure. A quiet valve helps, but a pressure regulator may be what you need if the fill is violent.
Worked Example: Setting the Water Level
Most tanks work best with the water about 1 inch below the top of the overflow tube. If your overflow tube is 10 inches above the tank floor, the water line should sit near 9 inches. Raise the float cup until it reaches that line, flush, and check. Too high wastes water and can drip into the overflow; too low gives a weak flush.
How to Replace a Fill Valve
- Turn off the supply valve and flush to empty the tank. Sponge the leftover water.
- Disconnect the supply line from the base of the old fill valve and loosen the locknut under the tank.
- Lift out the old valve, and set the new valve at the right height before you tighten the nut.
- Tighten the locknut by hand and a quarter turn with pliers. Overtightening can crack the tank.
- Reconnect the supply, clip the refill tube to the overflow, and turn on the water. Adjust the float and check for leaks.
Durability and Ownership
Fill valves typically last years but fail through mineral buildup, worn seals and hard water. A valve that hisses, runs after the tank is full, or refills randomly is a candidate for replacement. Clean the seal with a cloth during maintenance. Replace the supply line at the same time, since cracked braided lines are a common leak source.
Spec Cheat Sheet
| Valve | Min height | Max height | Warranty (per maker) | Adjustment |
|---|---|---|---|---|
| Fluidmaster 400H | 9 inches | 14 inches | 7 years | Separate dials for level and bowl refill |
| Korky 528MP | 8.5 inches | 14 inches | Check maker page | Tool-free height |
| Korky 528 | 7.75 inches | 13.5 inches | 5 years | Tool-free height |
Troubleshooting a New Valve
If the toilet runs after the new valve is in, work through three checks. First, the refill tube: if it is pushed down inside the overflow pipe below the water line, water can siphon back and cause cycling, so clip it above the water. Second, the water level: if it sits above the overflow tube top, the tank drains constantly. Lower the float until the water stops about an inch below the tube. Third, the supply line and debris: flush the line before connecting it by running water into a bucket for a few seconds, since sand and rust flakes can lodge in the valve seat.
If the valve hisses when the tank is full, the seal is probably not sitting flat. Turn the water off, take the cap off, rinse the seal and reseat it. Persistent hissing after that means the supply pressure may be above about 80 psi, which strains any fill valve. A pressure regulator on the main line protects the whole house.
Water Savings Example
A fill valve set to the right level and adjusted for a 1.28 gallon flush can save a small amount each flush compared with an overfilled tank. In a home flushing 20 times a day, a mere 0.1 gallon of unnecessary fill adds up to about 60 gallons a month, which is the same as a mild leak and entirely avoidable.
Frequently Asked Questions
How do I know if my fill valve is bad?
Symptoms include a constant hiss, a toilet that runs on, slow filling and a tank that overflows into the tube. If cleaning does not help, replace the valve.
Are universal fill valves compatible with all toilets?
They fit most standard residential toilets, but not every tank. Pressure-assist units and some one-piece toilets need specific parts, so check your model.
Which is better, Fluidmaster or Korky?
Both are reputable. Fluidmaster has more adjustment dials; Korky is known for quiet operation and clean installation. The better fit usually comes down to your tank height.
Can I replace a fill valve myself?
Yes, it is a common DIY job taking around 20 to 30 minutes with an adjustable wrench or pliers. Turn off the water first.
Why does my toilet fill valve make noise?
Noise often comes from worn washers, high water pressure or a valve nearing the end of its life. A new quiet-fill valve usually resolves it.
