How Long Should It Take to Fill a Toilet Tank? (Fix Slow Filling Toilet NOW)

Filing a regular toilet tank should be a matter of a few minutes after you flushed — a maximum of 3 minutes. However, at times your toilet may take more than 3 minutes to fill up, if this is the case, you should look into what’s going on inside.

To save you from too much trouble, we are here today to tell you how long should it take to fill a toilet tank, and more importantly, we’ll be showing you how to troubleshoot a slow filling tank.

How Long Should It Take to Fill a Toilet Tank?

The time for a toilet tank to fill up largely depends on its design, and size, as the volume can be anywhere between 1.6 to 7 gallons.

Generally, it takes about a minute or so for home toilet tanks which hold around 1 to 3 gallons of water, and for larger toilet tanks, the time is a bit longer, but never more than 3 minutes if things are working properly.

Troubleshooting a Slow-Filling Toilet Tank

You won’t always need a professional to fix a slow-filling toilet tank. Here are a few methods you could give a shot if your toilet tank is taking too long to fill up.

Step 1: Adjusting the Valve of the Water Supply

If the valve is not completely open, water cannot flow properly, leading to a slow-filling toilet tank. Simply open the valve by turning it anti-clockwise, and check if the issue remains. If it’s still filling up slowly, check if the water pressure of the stream is weak, and if it is weak, then this is a matter of plumbing.

Step 2: Regulating the Float

The float in your toilet should either look like a plastic ball or a miniature-sized cylindrical buoy. When the float isn’t adjusted properly, the toilet tank may not be filled completely. Therefore, if needed, adjust the float by twisting the screw adjacent to the fill valve.

You may read our in depth guide on the toilet fill valve types that most fit on your toilet tank.

Step 3: Checking the Flopper

The flapper of the toilet needs to have a strong seal; if it doesn’t, then water will flow little by little into the bowl, which will increase the time required to fill up the tank. Spot the flapper, and if you see that water leaks from it, then you will have to get a new flapper to replace the old one.

We recommend you to get the Fluidmaster 400ARHRKP10 Universal High Performance all in one repair kit for your toilet.

Step 4: Scrubbing Down the Tank

Toilet tanks are prone to getting really dirty since a build-up of dirt can restrict the water flow. If your toilet tank is dirty, you will have to turn it off and empty it. Wear some gloves, and take a toothbrush with vinegar on it, and clean all the toilet components to make sure it’s all squeaky clean.

After that, turn the water tank on and let the parts soak for 5 to 7 hours, and then flush. Also, you can read our article on how to clean Toilet Siphon Jet for a Better Flush.


If your toilet is not filling properly or is filling slowly, this guide should be of help. However, if you feel the issue is more technical, call a professional; otherwise, you might make a mess!

With an idea of how long it should take to fill a toilet tank and the methods of troubleshooting, you should be able to fix any of the minor issues discussed above.

Hello, I'm Jon C. Brown, an expert in the field of toilets. With over 15 years of experience in this industry, a significant portion of my life has been devoted to crafting high-quality toilets and bathrooms. Consequently, I've received countless inquiries about the toilet and bathroom industries. That's why, I've launched this website to provide top-notch solutions for all your toilet and bathroom related needs.

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