A running toilet wastes between 20 and 200 gallons of water per day — and the fill valve is responsible for that leak in over 80% of cases. The best toilet fill valve is a $10–$30 part that installs in under 10 minutes and can cut a household water bill by $50–$200 annually. Getting the wrong one means a second trip to the hardware store, a noisy refill cycle, or a valve that fails again in 18 months instead of lasting 7–10 years.
For most households, the Fluidmaster 400H-002 PerforMAX is the strongest all-around pick — faster fill than the standard 400A, quieter operation, and a 7-year warranty. If noise is your priority, the Korky 528MP QuietFILL Platinum is the quietest valve tested. Homeowners with Kohler Class Five toilets should go straight to the Kohler GP1083167 — the OEM valve engineered for that flush system.
This guide covers 7 top-rated fill valves, selected from Bob Vila, The Spruce, and Good Housekeeping recommendations, and verified on Amazon for current availability and review volume.
If your toilet tank keeps running after replacing the flapper, the fill valve is almost certainly the culprit. See our guide to toilet fill valve keeps running for a diagnostic checklist before you buy.
Most buyers search “toilet fill valve” and grab the first result — usually the Fluidmaster 400A standard model. The problem: if you have a low-profile tank (under 9 inches), a Kohler with a canister flush valve, or a TOTO with G-Max technology, the standard 400A will either not fit or will perform below the toilet’s original specification. Before purchasing, measure your tank height and identify your toilet brand and model number (printed inside the tank lid). A $12 valve bought right beats a $25 valve bought twice.
| Quick Picks — Best Toilet Fill Valves of 2026 | ||||
| Pick | Model | Key Feature | Height Range | Buy |
| Best Overall | Fluidmaster 400H-002 PerforMAX | Fast + quiet + 7-yr warranty | 9″–14″ | Amazon |
| Quietest | Korky 528MP QuietFILL Platinum | Near-silent refill, USA-made | 7¾”–13½” | Amazon |
| Best Budget | Fluidmaster 400A Anti-Siphon | World’s #1, $7–$12, universal | 9″–14″ | Amazon |
| Best Water-Saver | Danco HC660 HydroClean | Leak detection + cleaning jets | 11″–13⅘” | Amazon |
| Best for Kohler | Kohler GP1083167 Silent Fill | OEM Class Five, silent fill | Up to 12½” | Amazon |
| Best Complete Kit | Korky 4010PK Complete Repair | Fill valve + flush valve + flapper | 7¾”–13½” | Amazon |
| Best for TOTO | Korky 528T TOTO-Specific | G-Max / Power Gravity fit | 7¼”–13½” | Amazon |
Fluidmaster 400H-002 PerforMAX — Best Overall Toilet Fill Valve
| Spec Sheet — Fluidmaster 400H-002 PerforMAX | |
| Valve Type | Float-cup, anti-siphon |
| Fill Speed | 2× faster than standard ballcock; fills 1.6 GPF tank in ~45 seconds |
| Bowl Refill Control | Yes — independent dial adjustment |
| Tank Water Control | Yes — separate dial adjustment |
| Height Range | 9 in. to 14 in. (EZ-Twist adjustment) |
| Compatibility | Universal — fits Kohler, TOTO, American Standard, Gerber, most 2-piece and 1-piece |
| Anti-Siphon | Yes — code-compliant |
| Material | Corrosion-resistant plastic, Microban antimicrobial |
| Installation Time | Under 10 minutes — no tools required |
| Warranty | 7 years |
| Price Range | $16–$22 on Amazon |
If you own a standard American toilet and want the best toilet fill valve that outperforms the old standard without requiring brand-specific parts, the Fluidmaster 400H-002 PerforMAX is the right choice. It builds on the 400A platform — the same float-cup mechanism that ships inside over 90% of new American toilets — adding two critical upgrades: independent bowl and tank water adjustment dials, and a 7-year warranty. Verified on Amazon with 4.4+ stars across thousands of reviews.
The user profile for this valve is the homeowner with a 1.28–1.6 GPF two-piece toilet who wants the tank refilling in under 60 seconds. The 400H-002 fills a standard 1.6-gallon tank in approximately 45 seconds — compared to 3 minutes with an old-style ballcock. That speed matters in households with 3 or more people sharing one bathroom, where back-to-back flushing is common.
The bowl adjustment dial is underrated. In low-flow 1.28 GPF toilets, the bowl water level directly affects siphon strength during the flush. The 400H-002 lets you calibrate the exact amount of water that returns to the bowl post-flush — a detail most generic fill valves skip entirely.
Honest limitation: The 400H-002 has more adjustment components than the basic 400A, which means there are slightly more parts that can eventually wear. A small number of reviewers report that the bowl refill adjustment dial feels unnecessary for standard 1.6 GPF toilets where the default setting already works correctly. If your toilet is a standard 1.6 GPF model and you have no bowl refill issues, the simpler 400A at half the price does the same core job.
• Independent bowl and tank water adjustment
• 7-year warranty — longest in the Fluidmaster 400 line
• Fits 9″ to 14″ tank height — wider range than the 400A
• Anti-siphon code-compliant in all 50 states
• Microban resists bacterial buildup inside the valve
• Bowl dial is redundant on standard 1.6 GPF toilets
• Costs 2× more than the standard 400A
• External float cup can rub tank wall if not oriented correctly
Korky 528MP QuietFILL Platinum — Best Quiet Toilet Fill Valve
The 400H-002 is the speed champion. The Korky 528MP is the silence champion — and for a bathroom next to a bedroom or living area, near-silent operation matters more than a 15-second faster fill.
| Spec Sheet — Korky 528MP QuietFILL Platinum | |
| Valve Type | Internal float, diaphragm-controlled |
| Fill Noise Level | Near-silent — internal float eliminates open-air water rushing sound |
| Bowl Refill Control | Yes — refill adjuster included |
| Height Range | 7¾ in. to 13½ in. (twist-lock adjustment) |
| Compatibility | 99% of toilets — fits Kohler, American Standard, TOTO, Gerber since 1994 (1.6 GPF or less) |
| Anti-Siphon | Yes |
| Material | Chlorazone red rubber — chlorine, bacteria, and hard water resistant |
| Manufactured | Designed and manufactured in Wisconsin, USA |
| Installation Time | Under 10 minutes — no tools required |
| Warranty | 5 years |
| Price Range | $13–$18 on Amazon |
The Korky 528MP QuietFILL Platinum is the right fill valve if the bathroom is adjacent to a bedroom, a home office, or a main living area where tank refill noise becomes a daily irritant. Korky’s internal float design is the key differentiator: where Fluidmaster uses an external float cup that slides up a shaft with some water noise, the 528MP uses a sealed internal float that closes the diaphragm with almost no audible rushing sound.
Bob Vila recommends it as Best Silent-Fill Valve across multiple review cycles. The 7¾” to 13½” height range also makes it a better fit for lower-profile tanks that the 400H-002 (minimum 9″) cannot reach.
The twist-lock height adjustment is simpler than the Fluidmaster’s threaded shank — unlock, pull to height, lock. No threading or fine-tuning frustration. The 7¾”–13½” range is also shorter at the minimum end than the 400H-002 (9″ minimum), making the 528MP a better fit for lower-profile tanks.
The chlorazone rubber in the 528MP resists chloramines used in municipal water treatment — a real failure mechanism that standard rubber fill valve seals degrade against over 3–5 years. In areas with aggressive city water chemistry, this materials distinction matters for service life.
Honest limitation: The 528MP fills slightly slower than the Fluidmaster 400H-002 — in a side-by-side test with the same water pressure, the Korky takes approximately 10–15 seconds longer to complete a fill cycle. For high-traffic bathrooms where back-to-back flushes are common (households of 4+ people sharing one bathroom), the speed difference is noticeable. The Korky’s internal float is also harder to inspect if sediment causes a malfunction, since you can’t see the float position from the outside.
• Minimum 7¾” height — fits low-profile tanks
• Chlorazone rubber resists chlorine and hard water
• Made in USA — Wisconsin manufacturing
• Twist-lock adjustment — one-step, no tools
• Fits 99% of toilets, including post-1994 1.6 GPF models
• Internal float is hard to inspect if it gets stuck
• 5-year warranty vs. 7 years on the 400H-002
• At high water pressure (>80 PSI), may produce squealing
Fluidmaster 400A Anti-Siphon — Best Budget Toilet Fill Valve
The 528MP delivers quiet. The 400A delivers everything you actually need in a fill valve at a price point — under $12 — that makes stocking a replacement for every toilet in the house a reasonable decision.
| Spec Sheet — Fluidmaster 400A Anti-Siphon | |
| Valve Type | Float-cup, anti-siphon |
| Fill Speed | Approximately 60–90 seconds for 1.6 GPF tank at standard pressure |
| Bowl Refill Control | No — fixed refill tube |
| Height Range | 9 in. to 14 in. |
| Compatibility | Universal — most toilets, found in 90%+ of new American toilets as OEM |
| Anti-Siphon | Yes — code-compliant |
| Material | Corrosion-resistant plastic |
| Parts Availability | Universal — replacement seals and caps at every hardware store in the USA |
| Installation Time | Under 10 minutes — no tools required |
| Warranty | 5 years |
| Price Range | $7–$12 on Amazon |
The Fluidmaster 400A has been the world’s best-selling toilet fill valve since 1957 — factory-installed in more than 90% of new American toilets and the standard against which every other valve on this list is measured. If you want a replacement that installs in under 10 minutes, requires zero special tools, and can be serviced with parts available at any hardware store in the country, this is the valve to buy.
The 400A is the right choice for rental property owners who need a fill valve that maintenance staff can replace without ordering parts. At $7–$12 each, buying three costs less than one plumber service call. The external float cup is straightforward to diagnose: watch the float move during filling to immediately identify if it’s stuck, set too high, or rubbing the tank wall.
Honest limitation: The 400A’s external float cup can rub the tank wall if not centered during installation, causing the toilet to run. This requires draining the tank and repositioning the valve. The 400A is also audible during filling — not loud, but distinctly present at night. It has no bowl water adjustment, which means in some 1.28 GPF low-flow toilets, the default refill amount may be insufficient for a strong siphon.
• Replacement parts at every hardware store
• External float is easy to diagnose and adjust
• Factory OEM equivalent — works in 90%+ of toilets
• 5-year warranty
• Ideal for landlords / rental properties — zero special-order parts
• External float can rub tank wall if not oriented correctly
• No bowl water adjustment dial
• Slower fill than the 400H-002 PerforMAX upgrade
Danco HC660 HydroClean — Best Water-Saving Toilet Fill Valve
The 400A handles the basics. The Danco HC660 handles the basics plus actively conserves water, cleans the tank, and alerts you when something leaks — a fundamentally smarter valve for homeowners focused on utility bills.
| Spec Sheet — Danco HC660 HydroClean | |
| Valve Type | Float-cup with integrated mini-valve and leak sensor |
| Water Savings | Up to thousands of gallons per year via mini-valve calibration |
| Leak Detection | Yes — audible alert when leak detected |
| Tank Cleaning | Yes — water jet tubes flush sediment and rust from tank bottom |
| Height Range | 11 in. to 13⅘ in. |
| Compatibility | Most standard toilets — NOT compatible with Kohler or Gerber models |
| Installation | Tool-free — Smart Nut hand-tightens without wrench |
| Float Lock | Yes — shuts off water supply manually for repairs without valve access |
| Material | Corrosion-resistant plastic |
| Warranty | Limited lifetime warranty |
| Price Range | $20–$30 on Amazon |
The Danco HC660 HydroClean earns its Bob Vila “Best Fill Valve Only” designation because it does things no other fill valve in this price range attempts. The built-in mini-valve lets you calibrate the exact water refill level per fill cycle — not just adjusting the float height. According to Danco, proper calibration can reduce water consumption by thousands of gallons annually in a household averaging 5 flushes per person per day.
The water jet tubes at the base of the valve actively circulate water through the tank bottom during each refill, dislodging sediment and rust before they accumulate on the flapper seat — a common cause of flapper leaks that most homeowners misdiagnose as a bad flapper rather than underlying mineral buildup. The HC660 does passive tank maintenance with every flush.
The leak detection feature is a distinct advantage for vacation homes or rental units that go days between uses. If the valve detects water flowing when it shouldn’t, it emits an audible tone — early warning before a running toilet adds $30–$80 to a monthly water bill.
Honest limitation: The HC660 has a hard compatibility restriction: it does not work with Kohler or Gerber toilets. This is not a soft recommendation — those toilet brands use tank geometry and inlet configurations that the HydroClean’s design does not accommodate. Additionally, the height range of 11″–13⅘” is the narrowest of any valve in this guide. Tanks under 11 inches cannot use this valve at all.
• Tank-cleaning water jets with every fill cycle
• Mini-valve precision calibration for water savings
• Float lock for easy repair without shutting off supply
• Tool-free Smart Nut installation
• Limited lifetime warranty
• Narrowest height range (11″–13⅘”) — doesn’t fit low tanks
• Higher price than basic fill valves
• More components = more potential wear points long-term
Kohler GP1083167 Silent Fill Valve Kit — Best for Kohler Toilets
The HC660 brings smart features. The Kohler GP1083167 brings something different — OEM engineering from the toilet’s own manufacturer, built specifically for Kohler Class Five flush systems.
| Spec Sheet — Kohler GP1083167 Silent Fill Valve | |
| Valve Type | OEM Kohler silent fill — pressure-regulated diaphragm |
| Designed For | All Kohler Class Five toilets (Cimarron, Highline, Santa Rosa, Wellworth, Devonshire, Archer) |
| Fill Rate Inserts | Multiple fill-rate inserts included — adjustable flow speed |
| Noise Level | Silent fill — water enters below tank waterline, no rushing air-water sound |
| Height | Up to 12½ in. (standard Kohler Class 5 tank dimensions) |
| Compatibility | Kohler Class Five — NOT a universal replacement |
| Material | OEM Kohler-specified materials — designed for full product longevity |
| Installation | Includes all necessary hardware and complete instructions |
| Includes Flapper | No — fill valve only |
| Warranty | Kohler limited warranty — manufacturer-backed |
| Price Range | $25–$40 on Amazon |
The Kohler GP1083167 is the answer to a specific problem: Kohler toilet owners who install a universal fill valve and find that flush performance drops — slower bowl clearance, weaker siphon, or a longer fill cycle. The Class Five system’s fill valve is engineered to deliver water at a specific rate into a specific volume tank to initiate the siphon correctly. A universal valve works, but may not trigger the flush at full efficiency.
If you own a Kohler Cimarron, Highline, Santa Rosa, Wellworth, Devonshire, or Archer toilet, confirm the model number on the inside of the tank lid before ordering — all current Kohler Class Five models use the GP1083167. The included multiple fill-rate inserts allow you to slow the fill cycle for supply pressure below 30 PSI, an uncommon feature in OEM parts.
Honest limitation: The GP1083167 is exclusively for Kohler Class Five toilets. Non-Kohler owners have no reason to consider it. The price is $25–$40 versus $7–$22 for universal alternatives. Some Kohler owners note that the GP1083167’s internal mechanism is mechanically similar to the Fluidmaster 400 platform — meaning a universal 400H-002 may deliver comparable performance at lower cost. If your Kohler is under warranty, using the OEM part preserves the manufacturer’s service relationship.
• Silent fill — water enters below waterline
• Multiple fill-rate inserts for low-pressure situations
• Manufacturer-backed warranty
• Includes all hardware and complete installation instructions
• Designed for full Kohler product longevity
• $25–$40 vs $7–$22 for equivalent universal options
• Does not include flapper — additional purchase required
• Overkill for Kohler owners still under original warranty
Korky 4010PK Complete Toilet Repair Kit — Best All-in-One Fix
The Kohler OEM part protects Class Five performance. The Korky 4010PK takes a different approach entirely: instead of replacing just the fill valve, it replaces every internal tank component at once — fill valve, flush valve, flapper, and hardware — eliminating the question of which part is actually failing.
| Spec Sheet — Korky 4010PK Complete Repair Kit | |
| Kit Includes | 528 fill valve, 4020 flush valve, 2001 flapper, 464 gasket, hardware |
| Fill Valve | Korky QuietFILL 528 — same core as the 528MP but non-Platinum |
| Flush Valve | Korky 4020 — 2-inch, compatible with most 2-piece toilets |
| Flapper Material | Chlorazone red rubber — resists chlorine, bacteria, hard water |
| Fill Valve Height | 7¾ in. to 13½ in. |
| Compatibility | Universal — all major toilet brands, 2-piece designs |
| Noise Level | Quiet — QuietFILL valve design |
| Manufactured | Made in USA |
| Installation | Basic tools required for flush valve replacement |
| Warranty | 5 years on fill valve and flapper |
| Price Range | $25–$35 on Amazon |
The Korky 4010PK earns its Bob Vila Best Overall Repair Kit designation by eliminating diagnostic uncertainty. When a toilet is running, slow-filling, or flushing weakly and is 8–15 years old, the professional answer is to replace all three major tank components at once. The 4010PK costs $25–$35 versus $30–$45 if you bought each component separately.
The included Korky 4020 flush valve is what makes this kit worth it over buying just the fill valve. A worn flush valve seat causes the identical symptom as a bad fill valve — a running toilet. Replacing the flush valve eliminates that variable entirely.
If your toilet returns to running within 6 months of a flapper replacement, the flush valve seat is almost certainly worn past the point where a new flapper can seal it. The 4010PK costs $25–$35 versus $30–$45 if you bought each component separately.
Honest limitation: Replacing the flush valve requires removing the tank from the bowl — draining completely, disconnecting the supply line, and unbolting the tank. It takes 20–30 minutes and is within DIY capability, but it’s not a simple swap like replacing just the fill valve. If you only need a fill valve, the 4010PK includes parts you may not need and doesn’t save meaningful money over individual purchases.
• Eliminates diagnostic guesswork on older toilets
• Costs less than buying parts individually
• Made in USA — chlorazone rubber resists hard water
• QuietFILL valve — near-silent operation
• Bob Vila Best Overall Complete Repair Kit
• Overkill if you only need a fill valve
• Requires more installation time than simple fill valve swap
• 2-inch flush valve only — not compatible with 3-inch flush valves
Korky 528T TOTO-Specific Fill Valve — Best for TOTO Toilets
The Korky 4010PK handles universal repairs. The Korky 528T handles a specific and frequent request: restoring fill performance in TOTO G-Max and Power Gravity toilets when a universal valve underperforms the original spec.
| Spec Sheet — Korky 528T TOTO Fill Valve | |
| Valve Type | Korky QuietFILL internal float — TOTO-optimized connector |
| Designed For | TOTO G-Max and Power Gravity toilets — G-connector outlet type |
| Height Range | 7¼ in. to 13½ in. |
| Connector Type | G-connector — matches TOTO’s internal tank plumbing geometry |
| Noise Level | Near-silent — same QuietFILL internal float as the 528MP |
| Material | Chlorazone rubber — resists chlorine, bacteria, hard water |
| Manufactured | Made in USA — Wisconsin |
| Includes | Fill valve, refill tube, metal clip, mounting nut, cone washer, coupling nut, instructions |
| Warranty | 5 years |
| Price Range | $14–$20 on Amazon |
TOTO G-Max and Power Gravity toilets use a G-connector outlet — a specific internal fitting that standard universal fill valves can technically connect to but often mismatch in refill tube geometry, causing an undersized bowl refill or a noisy fill cycle. The Korky 528T solves this with a TOTO-matched G-connector that fits correctly without adapter workarounds.
TOTO is the world’s largest toilet manufacturer, and the G-Max flush system — found in the Drake, Drake II, and UltraMax series — is engineered around a 3-inch flush valve and a specific siphon jet trajectory. The fill valve’s role is to restore exactly the right water volume to the tank and bowl after each flush.
If you own a TOTO Drake, Drake II, or UltraMax and the bowl refill seems weak or the fill cycle sounds different after a standard replacement, the 528T restores factory specification without requiring a TOTO OEM part at 3–5× the cost.
Honest limitation: The 528T is specifically for G-Max and Power Gravity TOTO models. Newer TOTO Washlet+ and Neorest models with integrated bidet systems have different fill valve configurations and may require a TOTO OEM part. At water pressure above 80 PSI, the Korky 528 series can develop a squealing sound — a documented issue requiring supply pressure reduction to resolve.
• Near-silent QuietFILL operation
• Restores original bowl refill volume and performance
• Made in USA — chlorazone rubber
• 7¼” minimum height — fits TOTO’s standard tank profile
• Much less expensive than TOTO OEM replacement parts
• Squealing at high water pressure (>80 PSI)
• Internal float harder to inspect than external float design
• Refill tube clip feels less sturdy than competing designs
What Most Fill Valve Guides Get Wrong — The 3 Factors That Actually Matter
Most fill valve comparisons rank products by price and star rating alone. That misses the variables that determine whether a valve will work correctly in your specific toilet and last its rated lifespan. Three factors consistently separate a valve that performs for 7–10 years from one that fails in 18 months.
Municipal water pressure in U.S. homes ranges from 40–100 PSI. Fill valves are typically rated for 20–80 PSI. Homes above 80 PSI can cause Korky 528-series valves to squeal and Fluidmaster external floats to overshoot the shut-off point. Before buying any fill valve, test your home’s water pressure with an inexpensive gauge ($8–$12) attached to an outdoor hose bib. Pressure above 80 PSI requires a pressure-reducing valve (PRV) on the main line — no fill valve alone will solve a high-pressure fill problem permanently.
Fill valve failure in hard water areas (hardness above 180 mg/L, common across the U.S. Southwest and Midwest) is almost always a mineral buildup issue. Calcium carbonate clogs the inlet strainer and accumulates on the diaphragm seal, preventing a clean shutoff. In these conditions, a fill valve with chlorazone rubber seals (Korky 528 series) outperforms standard valves by 2–3 years. The Danco HC660’s tank-cleaning jets also reduce sediment accumulation on valve components.
External float cups (Fluidmaster 400 series) require clearance from all tank walls — if the float contacts porcelain during filling, the valve runs constantly. Internal float designs (Korky 528 series) eliminate this risk but make the float invisible during diagnostics. If the tank is under 7 inches wide at the valve location, the Korky internal float design is the safer choice to avoid installation clearance issues.
A universal fill valve — Fluidmaster 400A or 400H-002 — is the right answer for approximately 85% of American toilets. Skip the universal and go OEM when: your Kohler toilet is under warranty and performance dropped after a universal fill valve install (the Class Five siphon system is sensitive to refill volume); your TOTO G-Max flush sounds weaker after a standard replacement (the G-connector geometry matters); or your toilet is a European-import model with a bottom-fill valve configuration (common in Swiss Madison and some Duravit designs) where a standard anti-siphon side-inlet valve physically won’t fit the tank inlet port. In those cases, the OEM-matched valve costs $10–$25 more and saves $80–$300 in a service call to diagnose why the flush performance degraded.
Head-to-Head Decision Matrix — Choosing the Right Fill Valve
| Your Situation | Best Valve | Why |
| Standard toilet, want the upgrade over basic | 400H-002 PerforMAX | Faster fill, bowl adjustment, 7-yr warranty |
| Bedroom-adjacent bathroom, noise is the issue | Korky 528MP | Near-silent internal float, USA-made rubber |
| Rental property or multiple bathrooms | Fluidmaster 400A | Parts at every hardware store, under $12 |
| High mineral content water, utility bill concerns | Danco HC660 | Tank-cleaning jets, leak detection, precision calibration |
| Kohler Class Five toilet (Cimarron, Highline, etc.) | Kohler GP1083167 | OEM fit, preserves Class Five flush performance |
| Toilet is 10+ years old, multiple symptoms | Korky 4010PK | Replaces everything — eliminates diagnostic guesswork |
| TOTO G-Max or Power Gravity toilet | Korky 528T | G-connector geometry, restores TOTO performance |
Frequently Asked Questions — Best Toilet Fill Valve
What is the best toilet fill valve for most American homes?
The best toilet fill valve for most American households is the Fluidmaster 400H-002 PerforMAX. It fits the widest range of toilet brands (9″ to 14″ tank height), fills a standard 1.6 GPF tank in approximately 45 seconds, includes independent bowl and tank water adjustment, and carries a 7-year warranty — all for under $22 on Amazon. If quiet operation is the primary requirement, the Korky 528MP QuietFILL Platinum is the better choice at $13–$18.
Four symptoms indicate a failing toilet fill valve: (1) constant running or hissing after the flapper has been confirmed seated — the valve diaphragm is worn and not sealing shut; (2) slow tank fill taking over 3 minutes — the inlet strainer is clogged with sediment; (3) fill cycle that starts and stops intermittently without a flush — the diaphragm is partially failing; (4) loud vibration or whistling during fill — the valve is waterlogged or the inlet pressure is exceeding the valve’s rating. A new fill valve costs $7–$30 and resolves all four of these problems. See our full guide to toilet fill valve keeps running for a step-by-step diagnostic process.
What is the difference between Fluidmaster and Korky fill valves?
Fluidmaster uses an external float cup — visible, easy to diagnose, fast to fill, with a 7-year warranty on the 400H-002. Korky uses an internal float design that is quieter but harder to inspect. Korky’s twist-lock height adjustment is faster; Fluidmaster’s threaded shank allows finer precision. Korky’s chlorazone rubber seals perform better in hard water. For speed and float serviceability, Fluidmaster wins. For noise reduction, Korky wins. Learn more in our guide to types of toilet fill valves.
A quality fill valve lasts 5–10 years under normal residential use. Actual service life depends on water quality (hard water shortens life by 30–50% in areas over 180 mg/L hardness), water pressure (above 80 PSI accelerates diaphragm wear), and flush frequency (a family of 5 flushing 5 times each daily cycles the valve ~9,100 times per year). Fluidmaster’s 400H-002 carries a 7-year warranty; Korky’s 528MP carries 5 years.
Can I install a toilet fill valve myself?
Yes — replacing a toilet fill valve is straightforward. Shut off the supply valve, flush to empty the tank, unscrew the lock nut under the tank, pull out the old valve, insert the new one, set height to the fill line marker, hand-tighten the lock nut, reconnect the supply. No soldering, no pipe cutting. Under 15 minutes for most homeowners. Parts cost $7–$30 versus $85–$150 for a plumber service call. See our fill valve type guide before selecting a replacement.
An anti-siphon fill valve includes a built-in backflow preventer that stops contaminated tank water from siphoning back into the home’s supply line during a pressure drop event. All fill valves on this list include anti-siphon protection, and most U.S. plumbing codes require it. Older ballcock-style fill valves typically lack this protection — replacing them with any modern float-cup valve brings the toilet into code compliance immediately.
What causes a toilet tank to not fill with water after flushing?
A toilet tank not filling has four probable causes: (1) the supply valve is partially closed — check first; (2) the fill valve inlet strainer is clogged — remove the cap and rinse; (3) the float is set too low; (4) the fill valve diaphragm is worn. The first three are correctable without replacement. The fourth requires a new valve. See our guides on toilet won’t fill with water and toilet tank not filling.
If you have a standard toilet and want the best overall performance → buy the Fluidmaster 400H-002 PerforMAX ($16–$22). It fills faster, adjusts more precisely, and its 7-year warranty means you likely won’t think about this again for a decade.
If your bathroom is adjacent to a bedroom or living area and noise is the problem → buy the Korky 528MP QuietFILL Platinum ($13–$18). The near-silent internal float eliminates the rushing water sound, and chlorazone rubber outlasts standard seals in hard water.
If you own rental properties or want the most serviceable valve with parts everywhere → buy the Fluidmaster 400A ($7–$12). At under $12, you can stock one in every bathroom cabinet. When something goes wrong at 10 PM, the replacement is already under the sink.
Toilet Fill Valve Replacement: What It Costs and When to Hire Out
Replacing a toilet fill valve yourself costs $7–$35 in parts and 10–30 minutes of time. A licensed plumber charges $85–$150 for a fill valve replacement and $150–$275 if the flush valve also needs replacement. The extra plumber cost covers tank removal and gasket seating — steps most DIYers handle without issue but that require familiarity with tank bolt torquing to avoid cracking porcelain.
Hire a plumber when: the supply shut-off valve is corroded and won’t fully close (requires professional attention before any tank repair); when the toilet is a specialty model with integrated electronics like a TOTO Washlet+ or Kohler Veil; or when the toilet is wall-mounted with an in-wall carrier frame requiring access panel removal. For standard floor-mounted toilets, fill valve replacement is a reliable DIY project under $30.
For a complete breakdown of service call pricing across U.S. regions, see our guide to toilet installation cost, which covers both part replacement and full toilet installation labor rates.
Adjustable Toilet Fill Valve: How to Set the Water Level Correctly
The water level inside a toilet tank should sit approximately 1 inch below the top of the overflow tube — the tall pipe in the center of the tank that prevents overfilling. Too high wastes water and risks overflow; too low means the flush lacks volume to clear the bowl, causing double-flushing.
On the Fluidmaster 400A and 400H-002, adjust the float height by rotating the threaded shank — raise it to raise the water level, lower to reduce. On Korky 528 series valves, unlock the twist-lock collar, pull to the correct height marking, and re-lock. Both take under 2 minutes.
After adjusting, flush once and watch the fill cycle complete — water should stop exactly at the tank’s marked water line (typically 1 inch below the overflow tube top). If your toilet keeps slowly losing water after correct adjustment, the flapper is the next component to inspect.
See our guide to how to adjust toilet water level for a step-by-step visual reference on both Fluidmaster and Korky adjustment procedures.
Toilet Fill Valve Keeps Running: The Two Most Common Causes
When a toilet fill valve keeps running, the cause is almost always one of two components: the fill valve diaphragm is worn, or the flapper is leaking and forcing the fill valve to run continuously. The test takes 30 seconds: add 5 drops of food dye to the tank and wait 10 minutes without flushing. If dye appears in the bowl, the flapper is leaking. If no dye appears but the hissing continues, the fill valve is the failure.
A third cause is the float set too high — water reaches the overflow tube and runs into the bowl continuously. Diagnose by listening for water inside the overflow tube and correct by lowering the float. No tools needed.
For a full troubleshooting sequence, see our guides on toilet fill valve keeps running, dripping sound inside toilet tank, and how to fix a running toilet.
