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Fluidmaster K-400H-039 Toilet Fill Valve and Flapper Kit

Curated from 87 real Reddit conversations

Refreshed on: March 20, 2025

Fluidmaster K-400H-039 Toilet Fill Valve and Flapper Kit

Brand: Fluidmaster

Price: $15

Snoop Score:

9.2

Sentiment

10.0

Popularity

10.0

Technical

8.8

Buy on Amazon for $15 See All Toilet Spare Parts Reviews

As an Amazon Associate, I earn from qualifying purchases.

Snoop's Take

The Fluidmaster K-400H-039 High Performance Toilet Fill Valve with 2-Inch Adjustable Toilet Flapper Kit is designed to enhance the performance of your toilet by providing efficient water control and a reliable flush. This kit includes the PerforMAX fill valve, which is adjustable to fit various tank heights, and a water-saving flapper, ensuring your toilet runs like new while conserving water. Consumer feedback highlights several strengths of the Fluidmaster fill valve. Users appreciate its quiet operation, with one stating, "The fluidmaster still is the quietest one." Additionally, many have noted the longevity of the product, with one customer mentioning, "I've had one at least 10 years and it's still working fine." The forgiving nature of the rubber gaskets has also been praised, making installation easier for DIYers, as one reviewer pointed out that these gaskets allow for margin of error during installation. Based on the overwhelmingly positive feedback from users, the Fluidmaster K-400H-039 is highly recommended for anyone in need of a reliable toilet fill valve and flapper kit. Its high performance, ease of installation, and durability make it a standout choice in its category.

Not for you? Check out our other rated Toilet Spare Parts

Guess what. The fluidmaster still is the quietest one.
Positive Feedback

Which smart toilets (toilet/bidet combo) do plumbers recommend? There seems to be a lot of sub-$1500
Insightful Chatter

9.2

Fluidmaster K-400H-039 Toilet Fill Valve and Flapper Kit

Buy on Amazon for $15

Residential Use

9 / 10

Commercial Applications

10 / 10

Repair and Maintenance

9 / 10

DIY Projects

7 / 10

See how this compares to all Toilet Spare Parts

What it does well!

Key strengths users can’t stop talking about.

Fluidmaster fill valves are quiet

“Guess what. The fluidmaster still is the quietest one.”➕

“My go to choice is Fluidmaster with the brass shank :)”➕

Fluidmaster fill valves last a long time

“I've had one at least 10 years and it's still working fine.”➕

Fluidmaster toilet rings are forgiving for DIY installers

“If you have to ask this question, then go with rubber toilet ring - it's forgiving for DYI installer and seal is beyond stellar for any height/recess.”➕

Fluidmaster rubber gaskets allow for margin of error during installation.

“I particularly liked the fact that if it's your first time installing a toilet there is margin for error.”➕

Compare On All Talked About Dimensions

Product Name	Price	Score	See Details	Buy Now
Fluidmaster K-400H-039 Toilet Fill Valve and Flapper Kit	$15	9.2	Details	Buy
Fluidmaster 400ARHRKP10 PerforMAX All in One Repair Kit	$16	8.9	Details	Buy
Hidnvefen 3 Inch Toilet Flapper Replacement	$7	8.1	Details	Buy
Houpeoro Universal Toilet Flusher Replacement Kit	$15	8.0	Details	Buy
Hidnvefen Toilet Flapper Replacement Kit	$9	7.9	Details	Buy
Fluidmaster 400H-002 Performax Universal Toilet Fill Valve	$14	7.7	Details	Buy
Hidnvefen Toilet Handle Replacement Kit	$8	6.8	Details	Buy
Fluidmaster PerforMAX Universal Toilet Fill and Flush Valve Repair Kit	$14	6.7	Details	Buy
VRSS Toilet Flappers Replacement for 3 Inch Outlet Pipe	$5	6.5	Details	Buy
R&T Toilet Fill Valve Replacement Kit	$18	6.0	Details	Buy
Lychee Light Dual Flushing Toilet Push Button Replacement	$27	5.7	Details	Buy
Jabsco 29043-0000 Manual Toilet Spare Parts Base Valve Gasket	$24	5.2	Details	Buy
Shutao 2 Set RV Toilet Seal Kit for Dometic Toilets	$11	4.4	Details	Buy
FATCANMA RV Toilet Rubber Seal Kit Replacement	$9	4.4	Details	Buy
Leopauto 31705 RV Toilet Spare Parts Water Valve Kit	$13	3.1	Details	Buy

Core Power Plays

The specs and strengths that make it shine.

Discussion on the importance of a reliable seal and installation techniques

“If you do those things well the wax ring is almost an afterthought.”➕

“There's no amount of bolt tightening that will prevent teetering if your floor isn't flat.”➕

Mention of combining wax and rubber seal for better performance

“I'd opt for the "best of both worlds", it combines a wax ring and rubber seal in one.”➕

Hidden Hero Hacks

Unexpected tricks and side‑door uses you’ll love.

Preference for waxless rings over traditional wax rings

“I've replaced three toilets and went waxless for each one, never had a problem with them.”➕

Discussion about experiences with Fluidmaster vs. other brands

“It seems they last a few months to a couple years and then I can hear them leaking, running full time, or flushing by themselves.”➕

“I’ve had bad luck with the ones from box stores, never had much for issues with the pro 45B.”➕

Buyer’s Cheat Sheet

What to check before you click ‘Add to Cart.’

General preference for Fluidmaster over Korky

“I stand behind the fact that the brass shank is worth the extra couple dollars.”➕

“Not that one.”➕

Discussion about non-Fluidmaster toilet parts compatibility

“do you think a universal fluidmaster kit would be able to replace all the inside parts of this toilet tank?”➕

“The flapper. Isn’t a universal one.”➕

“There are two very similar, but incompatible Kohler flappers.”➕

“No that's a kohler toilet and a specific flapper.”➕

Bulk purchasing Fluidmaster parts is cost-effective

“its unreal. Real money makers.”➕

Discussion about fill valve sizing and compatibility

“The flapper doesn't show much wear at all, actually, seems like it's held up very well.”➕

“I got that fluid master kit, no complaints so far.”➕

Discussion on addressing bathroom humidity issues

“I just want to keep the dripping from causing water damage, we had that happen in our last house so I'd like to avoid it again.”➕

“I occasionally had this issue and it was more the water in the tank was a different temp from the air so condensation would form.”➕

“High humidity in the bathroom can lead to mold growth, damage to paint/drywall, wood rot, metal corrosion, etc.”➕

“I'm betting on it leaking down and using a lot of water.”➕

Discussion about testing for toilet leaks with food coloring.

“If some coloring ends up in the bowl, congrats, you have a leak!”➕

“if any blue is in the bowl you know it needs fixing.”➕

“If not, there’s a leak.”➕

Discussion on the importance of regular maintenance for toilets.

“It's crazy how much money a $10 part can save...”➕

“it is generally the first connection to your water line after it enters the house.”➕

Cautionary Callouts

Know the pitfalls before they catch you off guard.

Discussion about various smart toilets and reliability

“Which smart toilets (toilet/bidet combo) do plumbers recommend? There seems to be a lot of sub-$1500”➕

“It's an amazing item and I actually installed it myself.”➕

“There is only one that I have installed and not heard complaints about.”➕

“The Toto Washlet is the way to go, in my opinion (I’m a plumber)..”➕

Discussion about Korky fill valves being problematic

“Korky is the absolute worst quality.”➕

“Will never choose a corky.”➕

Drop-in reservoir cleaning tablets can damage toilet parts

“The problem is that they also dissolve the plastic and rubber of the internals.”➕

Hard water can cause flush valve issues

“The flush valve gets a hard water lime build up, so try replacing this first if the flapper doesn't work.”➕

Perception of declining quality in toilet replacement products

“I’m convinced the quality of everything sold in stores has just gone so far down hill, that the parts manufacturers expect this.”➕

Discussion about the durability of different brands of flappers

“I'm just surprised that I had better luck with the stock - contractor grade parts.”➕

“Look at Fluidmaster Pro series components and flappers that have a “chemical resistant” coating.”➕

“Even fluidmasters best valve is made of sh@t.”➕

Discussion on the effectiveness and installation procedures of wax vs rubber seals.

“Thoughts on using a traditional wax ring vs. a rubber gasket?”➕

“if you're not planning to remove the toilet any time soon I'd go wax.. they've worked well in current form for over 70 years.”➕

“As a first time toilet installer, it was great.”➕

“If your floor is level then wax is fine.”➕

Experiences with water bills related to toilet leaks.

“this $10 toilet part has cost us thousands of dollars in excess water use that we just never noticed.”➕

“Who the fuck is taking a shower at 1am, especially since I'm the only one here?”➕

“All over 22 fucking dollars. Laugh and learn.”➕