Toilet Fill Valves

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400AH - PerforMAX® Fill Valve

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  • Quietest, most powerful solution to fix and upgrade your toilet
  • Easy to install, Universal fit
  • 2X greater bowl refill delivers a more powerful flush for 1.6 or lower GPF toilets
  • Water saving roller clamp lets you regulate the fill level in the bowl
  • Best for newer, high efficiency toilets (HET), 1.6 gallons or less
  • EZ-Twist height adjusts from 10″ to 15″ to fit most tanks
  • 7 year warranty

The 400AH (formerly known as 400ARHRK) has been independently rated to be the best fill valve (top pick) for 2021 by SanitaryReview. To read the review, please click here: SanitaryReview

To download our free guide to fix common toilet problems please click here: Fluidmaster Toilet Repair Guide

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Fluidmaster® recommends the PerforMAX® fill valve for toilets manufactured from 1994 to the current time (works on older toilets). If you are replacing the fill valve, we recommend you also replace the flapper with the 502 flapper for the best performance. The 502 flapper works on both old and new 2 inch flush valve toilets.

The most powerful toilet fill valve on the market. The 400AH is also known as the 400ARHR. With efficient and ultra-quite fill the 400AH replaces other inefficient, or outdated fill valve designs. Help prevent excessive or inadequate bowl fill levels. The 400AH is a code approved, anti-siphon design, that won’t contaminate the fresh water supply. Some toilet models not supported: Glacier Bay® or Niagara® Flapperless Toilets, One Piece Toilets. Does not replace Side Entry Valves. Fluidmaster’s late Founder invented the fill valve technology in 1958.

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Watch this video on how to install Fluidmaster PerforMAX®:

To better understand how the 400AH PerforMAX® is different than the 400A fill valve, please watch this short informative video:

To check your toilet’s flush volume, please click here.

400AH - PerforMAX® Fill Valve

Download Installation Instructions


  • UPGRADE Toilet Repair Kit
  • ALSO REPLACE 2" Universal Toilet Flapper
  • ENHANCE Toilet Cleaner System

Cancer and Reproductive Harm -


The 400AH - PerforMAX® Fill Valve is available online, from our following retail partners.