Best toilet fill valve replacements

The 400H PerforMAX is the pick for most flapper toilets. Fluidmaster lists it for toilets with a 2-inch or 3-inch flush valve that use 1.28 to 3.5 gallons per flush. That covers the 1.6 and 1.28 gallon toilets made since 1994, and older 3.5 gallon tanks too. Fluidmaster’s range stops at 1.28, so check before you fit one to a toilet rated lower.

What sets it apart is two separate adjustments. A screw on top sets the tank water level, and a dial sets how much water goes to the bowl. Fluidmaster ships the bowl dial pre-set for most toilets. Turn it clockwise for less water and counterclockwise for more.

That bowl dial earns its keep on low-flow toilets. The code says the trap seal must refill after every flush. Fluidmaster’s guide has a pencil test: pour a gallon into the bowl, wait a minute, mark the line, then flush and dial the refill until the bowl stops at your mark.

The EZ-Twist body adjusts from 9 to 14 inches. Fluidmaster wants the top of the cap about 3 inches above the overflow pipe and the water line about ½ inch below it. The pipe itself has to sit at least 1 inch below the lever hole. Our diagram below shows all four marks.

The body is corrosion-resistant plastic with a silicone seal. Fluidmaster says the seals resist chlorine and hard water, and lists the valve as code approved and CSA certified. The wear part is the 242 seal under the cap. If the valve won’t shut off, flush debris out first, then swap the seal.

The warranty is 7 years. It’s void with in-tank drop-in cleaners that hold bleach or chlorine, which Fluidmaster says damage tank parts. Mansfield, Kohler AquaPiston, American Standard Champion 3 and canister flush valves need the refill tube hooked up another way.

The 400A is Fluidmaster’s long-running universal valve, and the company calls it the world’s top-selling fill valve. Fluidmaster says it’s best for toilets built before 1994 that use 3.5 to 7 gallons per flush. The 400H’s range tops out at 3.5 gallons, so above that the 400A is Fluidmaster’s pick. The 400LS further down shares its fit rules and adds a leak lock.

This version has a brass shank, the threaded part that goes through the bottom of the tank and takes the locknut. The shank washer comes pre-installed. Fluidmaster backs the brass shank model for 7 years, two more than the plain 400A’s 5 years.

The fit check takes a tape measure. Measure the overflow pipe in the middle of the tank, from the tank bottom to the top of the pipe. Fluidmaster says that if it’s 6 inches or taller, the 400A will fit. The EZ-Twist body adjusts from 9 to 14 inches.

Fluidmaster says the 400A works in toilets back to the 1950s. It names American Standard, Kohler, Gerber, Briggs, Mansfield, Eljer and Jacuzzi among the brands it fits. It also says it replaces old Burlington ballcocks, Delta Pro and Danco valves.

There’s no bowl dial like the 400H has. You set the tank level with the adjustment screw: clockwise raises it, counterclockwise lowers it. Fluidmaster recommends against an inline filter, since the valve lets solder, rust and dirt pass. If something sticks, take the cap off and flush it out.

If it cycles on and off at night, the valve isn’t failing. Fluidmaster calls that the Water Waste Signal, better known as ghost flushing: the tank is leaking into the bowl. Fix the flapper. Repair parts are sold on their own: cap 385, seal 242 and hardware 250.

Korky builds its QuietFILL Platinum pitch around noise. It says the 528MP was proven the quietest fill valve in lab testing. We found no published report of that test, so read it as the maker’s claim, not a measured result. Korky also says it fixes no-fill, slow-refill and running toilets.

Korky’s FAQ covers a drip during the fill. Water can come from the base of the shaft and the seam of the cover, and Korky says that’s normal. Water also runs from the refill tube into the overflow, which refills the bowl and washes the rim. If the valve won’t shut off, Korky’s first fix is to lower the valve.

Korky says it’s ideal for toilets made since 1994, which use 1.6 gallons per flush or less, and for newer high-efficiency toilets. It also claims a fit in 99% of toilets. A refill adjuster sets how much water goes to the bowl, so a low-flow toilet keeps its trap full.

The detail that matters on older pipes is the strainer. Korky says it catches sediment in the water and lets you service the valve. Fluidmaster takes the other approach and lets debris pass through. If your water carries rust or sand, that strainer is a reason to pick Korky.

Korky valves use an internal float, so the valve height sets the water level. Push the valve down until its water level mark sits about ½ inch below the top of the overflow. Then check that the C/L mark is 1 inch above the overflow. Minimum working pressure is 6 psi.

Korky’s sheet says no sealant or tape on the supply, hand-tighten only, and install the mounting nut beveled side up. Over-tightening that nut voids the warranty. Korky makes it in Wisconsin, and the 528MP carries 5 years.

The 528X is Korky’s long-life version of the same valve. Korky says its Chlorazone II rubber lasts twice as long as other fill valves, and calls the 528X its longest-lasting, most universal valve. Those are maker claims. What you can hold Korky to is the 10-year warranty, double the 528MP’s 5.

Both makers name their seal materials. Korky’s is its own Chlorazone II rubber formula. Fluidmaster says the 400H’s seals resist chlorine and hard water. Only Korky puts 10 years in writing.

Fit is the same as the 528MP. Korky lists 8½ to 14 inches of height, a fit in 99% of toilets and a design for newer high-efficiency toilets. The box holds the valve, a refill tube and clip, a refill adjuster, mounting hardware and a tamper-proof key.

Korky’s sheet says the tamper-proof key is for plumbers and property managers. Once the valve is locked at its height, it keeps someone from twisting it up or down. The 528MP’s sheet and listing show a key too, so it isn’t a 528X-only extra. The black top tells you at a glance it’s the 10-year valve; the 528MP has a silver top.

The install matches the 528MP. Mark the bowl’s natural water level with a pencil, flush and wait 2 minutes, then turn the refill adjuster until the bowl refills to your mark. Korky recommends a flexible supply line, connected hand-tight with no tape or sealant.

Amazon sells it as part 528XBP, and Korky lists 528XCM as an alternate part number for the same valve. The black-top 528XBP is the one we link. Korky’s warranty terms match the 528MP’s, with the same drop-in cleaner and mounting nut exclusions. Its listing says it fixes running, noisy, slow-refill and weak-flush toilets.

The 400LS answers one problem: a flapper that leaks. A normal fill valve tops the tank back up every time water seeps into the bowl, all day and all night. Fluidmaster’s Leak Sentry adds a lock. When the tank leaks, the float stays locked and the valve won’t refill until someone pushes the handle.

The toilet still works. The first flush after a leak only refills the tank, so whoever uses it next notices and the flapper gets fixed. The Amazon listing calls it ideal for multi-housing. That fits rentals, small offices and a basement bath nobody checks.

Setup takes one extra chain. With the tank lever held all the way up, pull the Leak Guard chain until the float cup is at the top of the shaft, then clip it to the lever with no slack. Don’t cross it with the flapper chain. If the lever has one hole, both chains go there.

Test it before the lid goes back on. Let the tank fill, then lift the flapper chain slightly so 3 or 4 inches of water drain out slowly. The valve should stay off. Fluidmaster says the flapper needs a plastic or metal chain, since nylon and vinyl straps stretch and throw it off.

Fluidmaster recommends the 400LS for toilets made before 1994 that use 3.5 to 7 gallons per flush. It has everything the 400A has, plus the lock, a water-saving roller clamp for the bowl refill and a 9 to 14 inch height range. Like the 400A, Fluidmaster lists one-piece toilets and side-entry valves as not supported.

Fine-tuning is slow by design. Fluidmaster’s sheet says 8 turns of the adjustment screw move the float only ½ inch. It also says to replace the supply connector if it’s worn or more than 5 years old. The warranty is 5 years.

If you’re opening the tank to change the fill valve, the flapper is often due too. This kit pairs the 400H PerforMAX valve with Fluidmaster’s 502 flapper, for toilets with a 2-inch flush valve. Fluidmaster names Kohler, Toto and American Standard among the brands it fits. The valve is the same 400H as the top pick, with the flapper added.

Size the flapper before you buy. Fluidmaster says to measure the drain hole the flapper covers. A hole about 2½ inches across takes a 2-inch flapper, and a hole about 3½ inches takes a 3-inch one. For the bigger size, Fluidmaster sells the K-400H-040-T5 kit.

The 502 is a solid frame flapper, which Fluidmaster says stops twisting and leaks. Its dial sets how long it stays open: a higher number holds it open longer and sends more water. The dial comes pre-set, so try a few flushes before you change it.

Chain length decides the flush. Fluidmaster’s guide says to clip the chain to the lever directly above the flapper with about ½ inch of slack, a small J shape. If the bowl refills too low, its troubleshooting page points to that slack and to a tank water line set lower than ½ inch below the overflow.

The guide adds one more check. The top of the overflow pipe must sit at least 1 inch below the lever hole. If it doesn’t, Fluidmaster says to mark it and cut it down with a hacksaw. Korky’s sheet gives the reason: below that, water can escape the tank.

Height is where the sources disagree. The kit page says 10 to 15 inches, while the 400H’s own page says 9 to 14. We list both in the conflicts table further down. The warranty is 7 years.

Some Glacier Bay and Niagara toilets don’t use a flapper at all. They use a flapperless flush system that needs its own fill valve. Fluidmaster’s 400A page lists them as not supported. The 703A is the valve it makes for them.

Fluidmaster calls the 703A a direct OEM replacement for both brands, meant to bring the toilet back to factory performance with a fast refill. It’s only for Glacier Bay or Niagara flapperless toilets. If your Glacier Bay has a flapper, it’s a standard tank, and this isn’t your valve.

The install has one catch. When you take the shock nut off the old valve, hold a face cloth under it. A tiny flow regulator sits inside, and Fluidmaster says you must put it back in the new valve. Hand-tighten the shock nut, and keep the valve level as you tighten it.

Turn off the water, turn the tabs ⅛ turn counterclockwise and lift the float arm off. The disc shut-off seal sits at the base of the arm. Cup a hand over the valve and run the water a few seconds to rinse out debris. Check that the metal pin isn’t bent before you lock it back.

The warranty is 1 year, far shorter than the universal valves on this page. Like every Fluidmaster valve, it’s not for tanks with bleach or chlorine drop-in tablets. Fluidmaster says those damage tank parts and can cause flooding, and using them voids the warranty.

Check your model before you order. Look for the Glacier Bay or Niagara name on the tank or on the old valve, then look for a flapper at the bottom of the tank. Fluidmaster says the 703A is only for those flapperless toilets, so confirm the old valve matches before you buy.