Understanding Fluidmaster 400 and 400A: A Comprehensive Comparison
The Fluidmaster 400 and 400A are both popular toilet fill valves, often causing confusion due to their similar names and appearances. While they share many similarities, there are distinct differences that might make one a better choice than the other for your specific needs. Let's dive into a detailed comparison to help you make an informed decision.
Fluidmaster 400: The Classic Choice
The Fluidmaster 400 has been a trusted name in toilet fill valves for decades. It's known for its durability, easy installation, and reliable performance. Here are some key features:
- Adjustable water level with a simple turn of the float arm.
- Performs well in both 3/8" and 7/16" supply lines.
- Comes with a 5-year warranty, reflecting its robust construction.
Fluidmaster 400A: The Upgraded Version
The Fluidmaster 400A is an upgraded version of the 400, incorporating modern features and improvements. Here's what sets it apart:

Fluidmaster 400 vs 400A: Key Differences
| Feature | Fluidmaster 400 | Fluidmaster 400A |
|---|---|---|
| Adjustable Water Level | Yes, with a float arm | Yes, with an easy-to-use dial |
| Supply Line Compatibility | 3/8" and 7/16" | 3/8" only |
| Warranty | 5 years | 7 years |
| Additional Features | None | Adjustable water level dial, 7-year warranty |
Which One Should You Choose?
The choice between the Fluidmaster 400 and 400A depends on your specific needs:
- If you need compatibility with both 3/8" and 7/16" supply lines, choose the 400.
- If you prefer the convenience of an adjustable water level dial and a longer warranty, opt for the 400A.
Both models are excellent choices for their respective use cases, offering a blend of durability, reliability, and easy installation. By understanding the subtle differences between the Fluidmaster 400 and 400A, you can make an informed decision that best suits your requirements.
More Details
03.06.2023 ... We compare the Fluidmaster 400A and 400H toilet fill valves and point out the similarities and differences. @HacksbyDad If you would like to ...

18.02.2021 ... The fill valve just says '400 model'. When I type this on Amazon I get a bunch of different fill valves with a lot of different letters (400a, 400ar, 400ap, ...

Hacks by Dad compares Fluidmaster 400A vs 400H toilet fill valves. Discover key differences in design, performance, and warranty.

What is the difference between the 400A and 400H toilet fill valves? The 400A is a standard refill valve that controls the water in the tank, it controls fill ...

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18.04.2018 ... This short video shows a comparison of Fluidmaster's 400A toilet ... Comparison of Fluidmaster 400A and Fluidmaster 400AH PerforMAX® Toilet Fill ...

25.01.2023 ... The 400A was designed for toilets manufactured before 1994 using 3.5–7 gallons per flush (GPF). The current federal standard is 1.6 GPF, with ...

Fluidmaster® 400A universal toilet fill valve is the #1 best-selling fill valve in the world! A universal design, with an adjustable height from 9 to 14 in ...

Fluidmaster® recommends using the 400A fill valve in toilets that date prior to 1994 with flush volumes between 3.5 and 7 gal per flush. Fluidmaster®'s 400A ...

Q: Is this the same as fluidmaster 400a? the float on mine says fluidmaster 400. ... Videos must be at least 5 seconds. ... A: Yes. The Pentair T29 and the ...

Toilet problems? - Learn how to replace and install a Fluidmaster fill valve (aka ballcock) to help prevent water waste, and to stop your toilet from ...

The 400A offers quick refill rates and replaces ballcocks and other toilet fill valves. A trusted and proven toilet fill valve, the 400A is built to last from ...

30.08.2017 ... Cleaning out the valve should help. On the other hand, a new 400A fill valve is about $7.50 and it will take you under 5 minutes to replace ...

The 400A is a trusted and durable toilet replacement part, consisting of corrosion-resistant materials combined with simple installation. Fluidmaster is the ...

24.03.2021 ... Find the Fluidmaster 400A Toilet Fill Valve at PlumbingSupply.com. https://www.plumbingsupply.com/fluidmaster-toilet-fill-valves.html#400 ...

09.09.2014 ... Fluidmaster 300 vs 400A Toilet Fill Valve Replacement Guide ... Fill valves often cause slow tank filling and constant running water issues.

04.10.2025 ... So I suppose hotels like the 400A because of this. And the PerforMAX should have the same shank. Ever installed a restrictor? I placed pinch ...

Fluidmaster® 400A Universal fill valve is recommended for toilets that date prior to 1994 with flush volumes between 3.5 and 7 gallons per flush.

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15.10.2024 ... a detailed diagram of a Fluidmaster 400A fill valve, a commonly used component in toilet tanks that regulates the water level and refills ...
