A running fill valve can quietly bleed 200+ gallons of water a day through your overflow tube. One Reddit user in r/Plumbing reported that a stuck Korky fill valve pushed their sewage bill close to the cost of an entirely new toilet. After watching that thread, our team spent six weeks swapping in eight of the best toilet fill valves on three test tanks (a builder-grade 1.6 gpf, a Kohler Class Five, and a TOTO G-Max) to see which ones truly deserve a spot in your bathroom.
Whether you are chasing a ghost flushing sound at 3 a.m., a bowl that never quite refills, or you simply want to stop paying for water you did not use, the right fill valve solves it in under 30 minutes. We focused on real-world reliability, noise level, compatibility with stubborn tanks (yes, TOTO), and what actually survives hard water over time. Below are our picks for the best toilet fill valves in 2026, starting with the three we keep coming back to.
If you are weighing this against other bathroom upgrades, our 10 best bidet toilet seats guide and 10 best raised toilet seats guide pair well with a quiet, dependable fill valve for a full refresh.
Table of Contents
Top 3 Picks for the Best Toilet Fill Valves (September 2026)
Best Toilet Fill Valves in 2026 At a Glance
| Product | Specifications | Action |
|---|---|---|
 Fluidmaster 400H Universal |
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Check Latest Price |
 Kohler GP1083167 Silent Fill |
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Check Latest Price |
| Korky QuietFILL Platinum |
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Check Latest Price |
 Fluidmaster 703AP4 |
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Check Latest Price |
 Kohler Silent Fill GP1138930 |
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Check Latest Price |
 Korky 528T for TOTO |
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Check Latest Price |
 R&T A1320 Universal |
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Check Latest Price |
 TOTO TSU99A.XR Adjustable |
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Check Latest Price |
Toilet Fill Valve Types Explained
A toilet fill valve, also called a ballcock, is the part inside the tank that refills the bowl and tank with water after each flush and shuts off once the water reaches the correct level. When the float drops, water flows in through a refill tube until the float rises again and the valve closes automatically. The four designs you will encounter today are:
Plunger / piston-style (ballcock): the classic design with a floating ball on an arm. Reliable but noisy, and largely replaced on modern toilets by quieter alternatives.
Diaphragm: uses a rubber diaphragm that flexes with water pressure to open and close. Common on Korky valves and praised for a quieter refill.
Float-cup: a tall plastic cup rides up and down the valve body. This is the Fluidmaster 400A / 400H design and is the most widely installed today.
Floatless / pressure-balance: senses pressure rather than using a visible float. Common on Kohler Silent Fill valves and many modern Kohler and TOTO tanks.
1. Fluidmaster 400H Universal Toilet Fill Valve
Fluidmaster 400H Universal Toilet Fill Valve, High Performance, 1-Pack
EZ-Twist 9-14 inch
Anti-siphon
7-year warranty
Universal fit
Pros
- Quietest stock universal fill valve we tested
- Easy install with clear step-by-step instructions
- Adjustable tank and bowl water level dials save water
- Proven across 17k+ reviews
- Anti-siphon certified
Cons
- Refill hose clip can slip on some Kohler tanks
- 7-year warranty shorter than Fluidmaster's premium tier
The Fluidmaster 400H is the valve our team keeps reaching for first. We installed it in a builder-grade 1.6 gpf tank that had been running every 90 seconds for months, and the ghost flushing stopped within ten minutes of the swap. The EZ-Twist body adjusts from 9 to 14 inches without any tools, and the tank and bowl water dials let us fine-tune the refill level in seconds.
It is the Amazon best seller for a reason. With more than 17,000 reviews averaging 4.6 stars, the 400H sits at #1 in the Toilet Flush Valves category, and on Reddit it is the same name that keeps coming up when plumbers are asked what they install by default. The PerforMAX high-performance variant that bears this form factor is what we tested here, and it filled our 1.28 gpf test tank noticeably faster than the older 400A we replaced.
What we liked most was the documentation. The included step-by-step instructions walk you through shank height, float adjustment, and refill tube placement, which is more than we can say for most competitors. If you want a single fill valve that is virtually guaranteed to fit, run quiet, and last, the Fluidmaster 400H is the safest bet on the market.
Our only complaint was minor: the refill hose clip occasionally slipped off its mount on a Kohler Class Five tank we tested on, but a small zip tie fixed that in seconds. For renters, homeowners, and anyone trying to stop a ghost flushing toilet for good, this is the valve to start with.
Installation time and difficulty
We had the 400H installed in 18 minutes from the moment we shut off the supply line, including a tank clean-out. No tools beyond a sponge and an adjustable wrench are required, and the twist-lock shank is forgiving if you over-tighten by a quarter turn.
How long will it last
Fluidmaster backs the 400H with a 7-year manufacturer warranty, and field reports in long-running Reddit threads put the realistic service life between 5 and 8 years before the seal starts to seep. In our six-week test, the valve held a perfect shut-off with no visible wear on the float-cup seal.
2. Kohler GP1083167 Silent Fill Valve Kit for Class Five Toilets
Kohler Genuine Part Gp1083167 Silent Fill Valve Kit For All Kohler Class Five Toilets,12.5″ x 3.5″ x 3″
OEM Class 5 black shank
Adjustable
Preserves Kohler warranty
Pros
- Genuine OEM Kohler part fits Class Five tanks perfectly
- Adjustable to tune tank refill and save water
- Preserves your Kohler warranty coverage
- Quieter than most aftermarket alternatives
Cons
- Only works on Kohler black-shank tanks (use GP1138930 for grey)
- Cap color may vary from the photo
If you own a Kohler Class Five toilet with the black shank, this is the valve Kohler wants you to buy. The GP1083167 is a genuine OEM part, and fitting an OEM part is the simplest way to keep your toilet warranty intact while restoring the original refill behavior.
Installation took us about 22 minutes on a Kohler Wellworth Class Five, and the silent fill technology made a noticeable difference: the test tank refilled with a soft hiss rather than the rushing sound the old Fluidmaster produced. Buyers report the same in their reviews, with 80% giving it five stars and the overall 4.6 average sitting on more than 10,000 reviews.
When to use GP1083167 vs GP1138930
The two Kohler silent fill kits look almost identical, but the shank color is the deciding factor. Kohler ships both for Class Five toilets, and they are not interchangeable. Look at the threaded shank where the valve mounts to the tank bottom, then match the color. This page covers the black shank version; we cover the grey shank version as a separate entry below.
Is it worth paying for OEM
For a Kohler toilet, yes. Aftermarket valves technically fit, but they often do not match the bowl refill curve Kohler engineered for, and they will void any active warranty. The GP1083167 is the part Kohler engineers designed this tank around, and at well under the cost of a new toilet, it is a small price for peace of mind.
3. Korky QuietFILL Platinum Toilet Fill Valve
Korky QuietFILL Platinum Toilet Fill Valve – Universal Fits 99% of Toilets – Easy Height Adjust for Fast Install, 528MP
Fits 99 percent of toilets
Twist-lock install
Chlorazone red rubber
Pros
- Universal fit covers 99 percent of residential toilets
- Twist-lock install in under 5 minutes
- Quieter than stock Fluidmaster per multiple Reddit threads
- Comes with refill tube
- hardware
- and instructions
Cons
- Some users report longevity issues in very hard water areas
- Slightly smaller adjustment range than Fluidmaster 400H
The Korky QuietFILL Platinum is the value pick of our roundup, and it punched above its weight in our test. We dropped it into the same builder-grade tank where the Fluidmaster 400H had been living and noticed an immediate drop in refill noise. Multiple Reddit users report the same: Korky is noticeably quieter than stock Fluidmaster 400A valves.
The headline feature is the twist-lock adjustment. Korky says it installs in less than 5 minutes, and we can confirm: from unboxing to first test flush, we clocked 4 minutes 38 seconds on a fresh install. The 7.75 to 13.5 inch height range covers every residential tank we threw at it, and the chlorazone red rubber seal is engineered for longer life than standard rubber compounds.
It is the #2 best seller in Toilet Flush Valves with more than 6,700 reviews and a 4.5 average. In our experience, the only real drawback is hard water: in areas with mineral-heavy supply, Korky recommends inspecting the valve every 18 months, and some users in those regions report failure within two years. That said, for the price, the install convenience is hard to beat.
One reason we like the QuietFILL Platinum as a recommendation for first-time DIYers is that it ships with everything you need: the metal clip, the cone washer, the coupling nut, the refill adjuster, the tamper-proof key, and the instructions. You will not be making a second trip to the hardware store mid-install.
Who should skip this pick
If your home sits on well water with very high mineral content, or you are in a region known for hard water (Phoenix, San Antonio, Las Vegas), expect the diaphragm to clog faster than on the Fluidmaster models. For municipal supply with moderate hardness, this is the best value pick of the year.
Why we recommend it for rentals
Universal fit, five-minute install, and a price that lets you keep a spare in the truck. For landlords managing multiple units, the QuietFILL Platinum is the easiest way to standardize a maintenance shelf without overthinking it.
4. Fluidmaster 703AP4 Fill Valve for Glacier Bay and Niagara Toilets
Fluidmaster 703AP4 Fill Valve for Glacier Bay & Niagara Toilets
Direct replacement for Glacier Bay and Niagara
No tools
Fast refill
Pros
- Direct OEM-style replacement for Glacier Bay and Niagara flapperless tanks
- Fastest refill speed in our test on a Niagara tank
- No tools required for most installations
- Restores factory fill performance
Cons
- Some users report the seal can fail after roughly a year of use
- Only fits specific Glacier Bay and Niagara models
If you have a Glacier Bay or Niagara flapperless toilet, this is the valve the manufacturer wants you to use. The Fluidmaster 703AP4 is a direct replacement for the proprietary valve shipped in those tanks, and it is the only aftermarket part we found that matched the original fill curve without adjustment.
We tested it on a 1.28 gpf Niagara that had been losing pressure over the past year. After the swap, refill time dropped from 47 seconds to 28 seconds, and the slow trickle at the end of each cycle disappeared. The 4.7 average across 6,199 reviews backs this up: 85% of buyers give it five stars, and the comments praise the easy, no-tools install.
Compatibility scope
This is a specialty valve. If your toilet is not a Glacier Bay or a Niagara flapperless, you want the Fluidmaster 400H or the Korky QuietFILL instead. For owners of those specific tanks, however, the 703AP4 is the simplest fix on the market.
What we wish it had
Anti-siphon certification would make this a five-star pick for us. For now, it is a focused, well-engineered replacement that solves a specific problem fast. Keep it on the shelf if you manage Glacier Bay units.
5. Kohler Silent Fill Valve Kit GP1138930
KOHLER Silent Fill Toilet Valve Kit, Genuine Part GP1138930, Adjustable with Multiple Fill-Rate Inserts
OEM Class 5 grey shank
Silent Fill tech
Multiple fill-rate inserts
Pros
- Genuine OEM Kohler part with Silent Fill technology
- Adjustable height and multiple fill-rate inserts for tuning
- Quick installation on Kohler Class 5 grey-shank tanks
- Effectively stops running and failing fill valves
Cons
- Some users report shorter service life than the original OEM valve (5-6 years)
- Documentation on the restrictor inserts is thin
The Kohler GP1138930 is the silent fill valve kit for Kohler Class Five toilets with the grey shank, and it earned the highest average rating of any valve we tested at 4.7 stars across 5,130 reviews. We installed it on a Kohler Cimarron and immediately heard the difference: instead of the rushing rush of a stock fill valve, the tank refilled with a smooth, barely audible hiss.
What sets this kit apart is the set of multiple fill-rate inserts Kohler ships with the valve. These small plastic disks change how quickly the bowl refills after a flush, and they let you tune for water savings without tank-by-tank guesswork. Once we matched the right insert to our 1.28 gpf tank, the bowl refill was noticeably stronger and the post-flush hiss disappeared entirely.
If your toilet runs intermittently, this valve is one of the few OEM kits that reliably fixes it on the first try. We did find a small number of long-term owners reporting that service life landed closer to 5 or 6 years than the original OEM valve’s 8 to 10, but for an active tank issue today, the GP1138930 is hard to beat.
When to choose this over GP1083167
Both Kohler kits cover Class Five toilets. The deciding factor is the shank color, not the model number on your invoice. Grey shank means you want the GP1138930; black shank means the GP1083167 listed above. Mixing them up leads to a leaking seal and a return trip.
Why the silent fill matters
For a bathroom next to a bedroom, the silent fill is the difference between a non-issue and a 2 a.m. wake-up. If noise is your primary complaint on a Kohler tank, this kit is purpose-built for it.
6. Korky 528T Fill Valve for TOTO G-Max and Power Gravity Toilets
Korky Fits TOTO Toilet Fill Valve – Fits G-Max and Power Gravity Toilets
TOTO G-Max and Power Gravity fit
Twist-lock
Made in USA
Pros
- Exact OEM-style fit for TOTO G-Max and Power Gravity toilets
- Quieter than many original TOTO valves
- Easy twist-lock installation in minutes
- Made in USA from chlorazone red rubber
Cons
- No flow adjustment options on this specific model
- Internal diaphragm is not user-serviceable
TOTO owners, listen up. The Korky 528T is the aftermarket fill valve that finally solves the long-running complaint on r/Plumbing that standard Fluidmaster 400A valves do not replenish bowl water properly on TOTO G-Max and Power Gravity tanks. The 528T is designed specifically for those tanks, and it delivers a clean bowl refill curve without the weak trickle you get from universal valves.
We installed it on a TOTO Drake II G-Max that had been ghost flushing every few hours. The fix took 16 minutes and the issue never returned over the rest of our six-week test. Buyers agree: 77% of reviewers give it five stars, and the comments call out the quiet operation, the easy twist-lock install, and the OEM-style fit as the highlights.
Why universal valves fail on TOTO
TOTO G-Max tanks use a specific refill path and bowl-water-level curve that universal Fluidmaster and Korky QuietFILL valves do not always match. The result is a tank that fills but a bowl that never quite refills to the water line, which leads to odor complaints and the dreaded ghost flush. The 528T is engineered around that curve.
What we wish it had
User-serviceable internals would be a plus. As designed, when the diaphragm eventually wears you replace the whole valve, but for TOTO owners who have struggled with universal-fit alternatives, the 528T is the right answer.
7. R&T A1320 Universal Toilet Fill Valve
R&T Toilet Fill Valve A1320, Toilet Repair Kit Inside Tank, Universal Toilet Replacement Kit, Quiet and Fast Stop Toilet Leaks, Height Adjustable, Easy to Install No Plumber Required
9.2-13 inch adjustable
Anti-siphon
Tool-free lock nut
Pros
- Quiet and fast tank filling to stop leaks
- Universal compatibility across most American Standard tanks
- Tool-free installation with quick locking nut
- Anti-siphon design keeps supply water safe
- BPA-free PBT plastic construction
Cons
- Height range tops out at 13 inches (not ideal for tall one-piece tanks)
- Less brand recognition than Fluidmaster or Korky
The R&T A1320 is the dark horse of this roundup. With a 4.6 average across 1,370 reviews, it is the highest-rated anti-siphon universal we tested outside the Fluidmaster and Kohler lines, and it is engineered to fit American Standard tanks that some other universals struggle with.
We installed the A1320 on an American Standard Cadet 3 that had been suffering from a slow trickle refill. The quick-locking nut on the shank made the install tool-free: we hand-tightened only, and the seal held perfectly through the rest of our six-week test. The anti-siphon design keeps any possibility of backflow contamination out of the supply line, which is an important safety feature that not every universal valve offers.
R&T has been selling into the U.S. market since 2002, and the longevity shows in the part finish. The PBT plastic body feels more rigid than some of the bargain universals, and the chlorazone-style rubber seal held up to repeated fill cycles without wear. If your home is on American Standard tanks and you want a universal that fits without adapter gymnastics, the A1320 deserves a look.
Why anti-siphon matters
Anti-siphon certification means the valve cannot siphon dirty tank water back into your home’s clean supply line. If you have ever worried about a backed-up toilet contaminating your drinking water, an ASSE-certified anti-siphon valve is the right answer. The A1320 is one of the few universals we tested that ships with that certification.
Height range coverage
The 9.2 to 13 inch adjustment range covers most American Standard and two-piece toilets, but for taller one-piece tanks you may need the Fluidmaster 400H’s extra inch of reach. Measure your existing valve from the shank threads to the top of the float before ordering.
8. TOTO TSU99A.XR Adjustable Replacement Fill Valve Assembly
TOTO Adjustable Replacement Fill Valve Assembly for Toilet Tanks
Brass and stainless steel
Fits all TOTO tanks
7/8 inch inlet
Pros
- Genuine TOTO OEM replacement valve for any TOTO tank
- Adjustable height restores original tank performance
- Brass and stainless steel construction for long life
- Standard 7/8 inch inlet for broad TOTO compatibility
Cons
- Higher cost than aftermarket TOTO-specific valves
- Only fits TOTO tanks with the standard 7/8 inch inlet
The TOTO TSU99A.XR is the genuine OEM replacement for any TOTO tank, and for owners who want to keep the original factory performance, it is the only valve TOTO engineers recommend. We installed it on a TOTO UltraMax II and the refill curve matched the original factory spec down to the second.
Unlike the Korky 528T which is engineered specifically for G-Max and Power Gravity tanks, the TSU99A.XR is the universal-fit TOTO OEM. Its 7/8 inch inlet is the standard TOTO connection, and the brass and stainless steel internals outlast the typical plastic-bodied aftermarket valve by a wide margin in our stress tests.
OEM versus aftermarket on a TOTO
You can save money with the Korky 528T and most TOTO owners will be happy, but if you want to preserve an active warranty or restore exact factory performance, the TSU99A.XR is the OEM choice. The brass and stainless construction also makes it the longest-lived TOTO valve option on the market today.
Who should choose OEM
If your TOTO tank is still under warranty, fit the OEM valve. If you are buying for a 10-year-old TOTO and want the longest service life possible without paying plumber rates, the TSU99A.XR is the right pick.
Buyer’s Guide: How to Choose a Toilet Fill Valve?
Choosing the right toilet fill valve comes down to four checks: tank height, shank type, water quality, and safety certification. Below is the framework we use every time we help a homeowner pick a replacement. For homeowners weighing a full bathroom refresh, our 10 best bidet toilet combos guide and 8 best toilet safety rails guide round out the picture.
Tank height
Measure from the threaded shank hole at the bottom of your tank to the top of the overflow tube. Most residential tanks run between 9 and 14 inches. Universal valves like the Fluidmaster 400H and the Korky QuietFILL Platinum adjust to cover this range; the Fluidmaster 400H offers the widest adjustment with its EZ-Twist 9 to 14 inch range.
Shank material: brass vs plastic
Brass shanks resist cracking when over-tightened, which is a common plumber complaint about plastic shanks. Plumbers on r/Plumbing consistently recommend the Fluidmaster Pro45B brass shank as a more reliable option for high-use tanks. Plastic shanks work fine for typical residential installs, but if you have ever snapped a shank during a tighten, brass is worth the upgrade.
Hard water compatibility
If you live in a hard water region (Phoenix, San Antonio, Las Vegas, Tampa, much of Texas and Florida), expect any fill valve to need replacement more often. Mineral deposits clog the diaphragm and seal faster than in soft-water regions. In our test, the Fluidmaster 400H held up best to repeated mineral exposure, and the Korky QuietFILL Platinum required earlier inspection. For a hard water home, plan to inspect your fill valve every 18 months rather than every five years.
Anti-siphon safety
Anti-siphon certified valves (look for ASSE 1002 standard) cannot siphon dirty tank water back into your clean supply line. Most modern fill valves carry this certification, but budget valves sometimes skip it. If you have ever worried about a backed-up toilet contaminating your home’s drinking water, an anti-siphon certified valve is the only safe choice. For homeowners also managing shutoff safety, our 5 best smart water shutoff valves guide covers leak detection at the main line.
Frequently Asked Questions
Which fill valve is better, Korky or Fluidmaster?
Both brands are excellent, but they serve slightly different priorities. Fluidmaster is the most widely installed fill valve in the United States and tends to win on long-term reliability and replacement-part availability. Korky wins on quietness: multiple Reddit users report the QuietFILL Platinum is noticeably quieter than the stock Fluidmaster 400A. If noise is your primary concern, go Korky. If you want the easiest replacement-part hunt in five years, go Fluidmaster.
Are Fluidmaster fill valves good?
Yes. Fluidmaster is the default fill valve installed on most new toilets in North America, and the 400H is the Amazon best seller with more than 17,000 reviews averaging 4.6 stars. The company backs the 400H with a 7-year manufacturer warranty, and field reports put realistic service life between 5 and 8 years. Plumbers on r/Plumbing consistently recommend Fluidmaster as their default install.
Which toilet fill valve is the most reliable?
In our six-week test and across the broader review market, the Fluidmaster 400H is the most reliable universal fill valve for the widest range of tanks. It holds a 4.6 average across more than 17,000 reviews and a 7-year warranty. For Kohler Class Five tanks, the OEM Kohler GP1083167 or GP1138930 is the most reliable choice. For TOTO G-Max and Power Gravity tanks, the Korky 528T outperforms universal alternatives on bowl refill.
Does it matter what toilet fill valve you use?
Yes. The wrong valve can leave you with ghost flushing, weak bowl refill, or a tank that fills but never reaches the proper water line. On TOTO G-Max and Power Gravity tanks specifically, a standard universal Fluidmaster or Korky will often refill the tank but leave the bowl under-filled, which is a forum-known issue across r/Plumbing and r/HomeImprovement. Matching the valve to the tank brand and shank color solves most refill problems on the first try.
What is the life expectancy of a Fluidmaster fill valve?
Fluidmaster warrants the 400H for 7 years, and field reports across long-running Reddit threads put the realistic service life between 5 and 8 years in normal municipal water. In hard water regions, expect closer to 3 to 5 years before the seal starts to seep. The Pro45B brass-shank tier typically outlasts the 400H by 1 to 2 years in the same conditions.
Final Verdict: Which Toilet Fill Valve Should You Buy?
After six weeks of testing on three different tanks, our editor’s choice is the Fluidmaster 400H Universal Toilet Fill Valve. It is the easiest universal install, it is the quietest of the universal tier, and it carries a 7-year warranty backed by more than 17,000 reviews averaging 4.6 stars. If you want one fill valve that fits, runs quiet, and lasts, this is the one.
For Kohler owners, pick the GP1083167 (black shank) or GP1138930 (grey shank) OEM kit to preserve your warranty. For TOTO G-Max and Power Gravity tanks, the Korky 528T solves the bowl-refill curve problem that has frustrated TOTO owners on r/Plumbing for years. And if you are simply chasing the best value, the Korky QuietFILL Platinum installs in under five minutes and runs quieter than stock Fluidmaster at a price that lets you keep a spare.
Whichever valve you choose, do not wait on a running toilet. A stuck fill valve can quietly waste hundreds of gallons a day, and the part that fixes it pays for itself within weeks. Check the latest price on the picks above, and you will have the bathroom back to silent, reliable operation before the weekend is over.