There are three reasons for adjusting toilet tank water levels. The first is a water level that is too high. When this happens the water can run over the top of the fill tube and down into the toilet bowl. Not only is this annoying, it also wastes water.

Not sure if the water level is the problem with your toilet? See the article 'Troubleshooting Toilet Problems' for a complete listing of all the toilet issues and the resources to solve the problems.

A second reason is having enough water for the toilet to flush properly. Toilets use water to create a siphon that removes waste and cleans the bowl. When too little water flows into the bowl, a weak or no siphon is created.

If you need to adjust the water level in your toilet tank, you want to see the article 'How To Adjust a Toilet Float'. Toilets can have different types of floats, this article will explain that.

A third reason would be to try and reduce the amount of water you use. This is probably a bad idea, given the above. You may be able to lower the water level slightly with no adverse affects.

Lowering the Water Level for a Running Toilet

You have two key components inside of your toilet. One is the toilet fill valve and the other is the flush valve. The fill valve allows water to enter into the tank and controls the amount of water inside the tank. The float is attached to the fill vavle.

The other component is the flush valve. It has a large opening at the bottom that releases water inside of the tank, so that the toilet can flush. The flush valve has a cylindical tube with an open top.

When the water level is too high, it spills over the top of the flush valve tube and spills into the toilet bowl. This wastes water and makes an irritating noise. Lowering the water level until it is just below the top of the flush valve will stop this problem.

See the article on 'adjusting a toilet float or ball cock' for more information and instructions on what to do.

Toilet Fill Valve Not Working

You adjusted the float and the toilet is still running. If it runs constantly, the fill valve is bad and needs to be replaced. You will need to obtain a fill valve kit and replace the valve.

See the article on 'Replacing a Toilet Fill Valve'. Follow this link to fix a running toilet that needs a new fill valve.  

Slow Flushing Toilet

For a slow flushing toilet, the problem is a water level that is too low. Toilets need the correct amount of water to operate. If the water level is too low the toilet will flush slowly, sometimes poorly or not at all.

A slow flushing toile is prone to clogging up, which is another messy problem that it is best to avoid. See the article, 'Fixing a Slow Flushing Toilet' for more information.

Reducing Your Water Usage

If you are adjusting the water level on your toilet to reduce the amount of water you use, you may want to consider other options. Lowering the water level in the tank will likely cause other problems that will be more costly than the water.

Toilets are designed to operate with a certain amount of water. This could be as much as 7 gallons per flush or as low as 1.28 (sse below) gallons per flush. If you have an older toilet, you could be wasting a lot of water with each flush. The solution would be to replace the toilet with one that uses less water, see 'Installing a New Toilet' for information on what is involved.

How Much Water Does My Toilet Use?

There have been different regulations put in place over time that govern the amount of water a toilet can use. Below you can see how the amount of water that toilets use has been drastically reduced over time.

Prior to 1982:        5 - 7 Gallons
1982 - 1990:        3.5 Gallons
1990 - 1994:        1.6 - 3.5
1994 - Present:        1.6 Gallons (Required by Law)
2005 - Present:        1.28 - 1.6 Gallons (The 1.28 gallons per flush is available, but not required)

To save water, you want to check and see how many gallons of water your current toilet is using. There might be a lable on the top of the base, just in front of the tank that tells you the gallons per flush.

If there isn't, look inside the tank to find out the manufacture date for the toilet. You can compare that date with the information above to see how much water you are using.

Some of the years had a range for the gallons per flush, so you can't be certain about those years. The only way to be sure is to measure the amount of water the toilet is using.

How To Measure Water Usage In a Toilet

It is a fairly simple process to measure the amount of water a toilet uses. The steps are listed below:

(1) Use a piece of masking tape to mark the water level in both the tank and the bowl of the toilet.
(2) Shut off the water supply to the toilet.
(3) Flush the toilet as you normally would.
(4) Use one quart or two quart measuring pitcher to refill the toilet tank and the bowl up to the marks.
(5) Add up the total number of quarts it takes to fill the toilet. Ideally, it should be a little over six quarts.


Thats all there is to it. If you have a toilet that uses more than three gallons of water per flush, you may want to consider replacing it with one that is more efficient. See the article 'Replacing a Toilet' for information on how difficult it is.

Adjusting the Toilet Tank Water Level

There are different kinds of floats that are used to control the fill valve. The article 'How To Adjust the Float on a Toilet' discusses how to adjust the various types.

Once you have adjusted the water level, flush the toilet a couple of times and make sure it is filling to the proper level. Most toilets have a fill line marked on the side of the tank, if not, the top of the flush valve is the mark. Is it filling to the proper level? Yes, you have completed a successful toilet repair.

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