Best Toilet Repair Kits (2026): Fix a Running Toilet Yourself for Under $30

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A running toilet is one of the cheapest fixes in your whole house, as long as you buy the right parts the first time. The aisle at the hardware store doesn’t make that easy. There are complete kits, fill valve kits, flapper-only packs, 2-inch, 3-inch, “universal” (which isn’t always universal), and they all look the same.

Here’s what to buy for each situation, and the one thing to check before you spend a dime.

Check this first: 2-inch or 3-inch?

Take the tank lid off and look at the opening the flapper sits on, at the bottom of the tank. Most older toilets use a 2-inch flush valve. A lot of newer, water-saving toilets use 3-inch. If you can fit two fingers across the opening, it’s probably 2-inch. If it’s closer to the size of a soda can, it’s 3-inch. Buying the wrong size is the number one reason these repairs fail.

Also, if you have a newer Kohler, Toto, or American Standard with an unusual canister or tower-style valve instead of a round flapper, skip the universal kits and buy the brand’s own replacement part.

How we picked

We compared what’s in the box, size compatibility, warranties, and price, and read through owner reviews and hands-on roundups from outlets like Bob Vila. Fluidmaster and Korky dominate this category for good reason: their parts fit the most toilets and they’re on every hardware store shelf if you need a replacement later.

Quick picks

1. Korky 4010 QuietFILL Complete Kit: best for a full rebuild

If your toilet’s old and more than one thing is acting up (running, slow refill, leaking between tank and bowl), just rebuild the whole thing. The Korky 4010 includes a fill valve, flush valve, flapper, and tank-to-bowl hardware, so you’re not making three trips to the store. Bob Vila named it their best overall toilet repair kit. It’s a bigger job, since you’ll pull the tank off the bowl to replace the flush valve, but it’s an afternoon project that makes an old toilet work like new. Check the Korky 4010.

2. Fluidmaster 400AKR All-in-One: best for most running toilets

For the classic “toilet keeps running” problem, this is the kit I’d grab. It covers the parts that usually fail, a fill valve and a flapper, plus a gasket, hardware, and even a universal tank lever in case your handle’s loose or broken. Fluidmaster’s 400-series fill valve is about as standard as it gets. See the Fluidmaster 400AKR.

3. Fluidmaster PerforMAX K-400H-039: best fill valve and flapper combo

If the flush valve and tank seal are fine, you just need the two parts that wear out. The PerforMAX kit pairs Fluidmaster’s high-performance fill valve with an adjustable 2-inch flapper, so you can dial in how much water each flush uses. It usually costs under $20 and fixes the vast majority of running toilets. View the Fluidmaster PerforMAX kit.

4. Korky 818BP QuietFILL: best for quiet refills

Old fill valves hiss and whistle loud enough to wake people up at 3 a.m. Korky’s QuietFILL valve is designed to refill quietly, and this kit pairs it with a 2-inch flapper. If your toilet is next to a bedroom, this is the one to get. Check the Korky 818BP.

5. Korky 2021BP Universal Flapper: best flapper-only fix

If the dye test (food coloring in the tank, wait 15 minutes, check the bowl) shows the flapper’s leaking and everything else works, you don’t need a kit. The Korky 2021BP is an adjustable flapper that fits both 2-inch and 3-inch valves, and it costs less than a fast-food lunch. See the Korky 2021BP.

Which one should you buy?

Toilet running but otherwise fine: start with just a flapper. Running and slow or noisy to refill: a fill valve and flapper kit. Old toilet with several problems, or water leaking between the tank and bowl: a complete kit. Not sure what’s wrong? Our step-by-step guide to fixing a toilet that keeps running helps you find the bad part before you buy.

One more tip: if you’re replacing flappers every year or two, hard water may be wearing them out. Here’s how to tell if you need a water softener.

FAQ

What is the best toilet repair kit?

For a full rebuild, the Korky 4010 QuietFILL Complete Kit. For the typical running toilet, the Fluidmaster 400AKR All-in-One or the Fluidmaster PerforMAX fill valve and flapper kit fixes most problems.

How do I know if my toilet needs a 2-inch or 3-inch flapper?

Look at the drain opening at the bottom of the tank. A 2-inch opening is roughly two fingers wide. A 3-inch opening is closer to the size of a soda can. Many newer water-saving toilets use 3-inch valves.

Are universal toilet repair kits really universal?

They fit most standard toilets, but not all. Toilets with tower or canister-style flush valves, and some Kohler, Toto, and American Standard models, need brand-specific parts.

Should I replace the fill valve and flapper at the same time?

If the toilet is more than a few years old, yes. They wear out on similar timelines, and replacing both saves you another repair soon.

How long does it take to install a toilet repair kit?

A flapper takes about five minutes. A fill valve and flapper kit takes 15 to 30 minutes. A complete kit with a new flush valve takes an hour or two because the tank has to come off.

Do I need a plumber to fix a running toilet?

Usually not. Most running toilets need a new flapper or fill valve, which are easy DIY jobs. Call a plumber if the tank or bowl is cracked, or if you’re not comfortable removing the tank for a flush valve replacement.

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