Fluidmaster’s 400H and 400A toilet fill valves adjust from 9" to 14" tall and Korky’s 528MP from 8-1/2" to 14". Measure the overflow pipe, then check that the valve can be set high enough above it.
What kind of toilet is it?
Fluidmaster and Korky match their fill valves to the gallons per flush (GPF) a toilet uses.
The fill valve to look for
A standard fill valve, such as Fluidmaster’s 400A
Fluidmaster lists its 400A as best for toilets built before 1994 that use 3.5 to 7 gallons per flush. Its height twists from 9" to 14".
On the package: Universal fill valve, adjustable height
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Start overThe fill valve to look for
Fluidmaster’s 400H or Korky’s 528MP
Fluidmaster advises its 400H for dual flush, high-efficiency and post-2005 toilets. Korky calls its 528MP ideal for toilets made since 1994 that use 1.6 gallons or less.
On the package: High-performance fill valve, adjustable height
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Start overThe fill valve to look for
Fluidmaster’s 703A
Fluidmaster lists the 703A as its fill valve for Glacier Bay and Niagara toilets.
On the package: 703A fill valve
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Start overThe fill valve to look for
Find the toilet’s model, then measure the tank
Fluidmaster puts most two-piece toilets on universal fill valves, though some toilets need their own type. Kohler prints the model number on the inside back wall of the tank.
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How to measure the tank
Measure from the bottom of the tank to the top of the overflow pipe, the open tube in the center of the tank.
| Fill valve | Adjusts from | Best for |
|---|---|---|
| Fluidmaster 400H PerforMAX | 9" to 14" | 2" and 3" flush valve toilets, 1.28 to 3.5 gallons per flush |
| Fluidmaster 400A | 9" to 14" | Toilets made before 1994, 3.5 to 7 gallons per flush; tanks with an overflow pipe 6" or taller |
| Korky 528MP QuietFILL Platinum | 8-1/2" to 14" | Toilets made since 1994, 1.6 gallons per flush or less |
Fluidmaster also makes the 703A for Glacier Bay and Niagara toilets.
Setting the height
The makers set the height against the overflow pipe in different ways. Fluidmaster’s 400H guide puts the top of the valve’s cap about 3" above the top of the overflow pipe. Korky’s 528MP has a critical level mark (C/L) on its cover that goes 1" above the overflow. Both want the overflow at least 1" below the hole the tank lever goes through, and the water to stop about 1/2" below the top of the overflow.
The IPC asks for an antisiphon fill valve made to ASSE 1002, with its backflow preventer at least 1" above the overflow pipe’s opening. Local code decides whether your area changes that.
The connection under the tank
The fill valve’s shank comes through the bottom of the tank, held by a locknut, and the toilet supply line’s 7/8" ballcock nut screws onto it. Fluidmaster and Korky both say to tighten them by hand only. Fluidmaster warns that overtightening can crack the valve or the tank, and Korky’s sheet rules out sealant or tape on the supply connection. For the line itself, see toilet supply line size.
Before you take the old valve out, turn the water off at the wall valve, flush, and soak up the water left in the tank. Fluidmaster says to replace the supply line too if it’s worn or you don’t know its age.