Why Do Low-flow Toilets Clog More Easily?

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Modern luxury bathroom (Photo: @try2benice via Twenty20)
Low-flow toilets are great for environmentally conscious homeowners, and they also use less water than a standard toilet, which saves you money on your water bill. One problem, though: Low-flow toilets tend to clog up more easily than a standard toilet. Read on for more about why low-flow toilets clog up more often and how you can make sure the toilet fill valve is adjusted properly.

Why Do Low-Flow Toilets Get Clogged More Easily?

Low-flow toilets, especially older models, can end up getting clogged easily. This is because they use less water, 1.2 gallons, compared to a standard toilet, which uses 1.6 gallons per flush. This means there’s less water to push waste down the drain pipe of a low-flow toilet and out to the sewer line or septic tank.
Problems originally arose when low-flow toilets were first introduced in the 1990s. The smaller volume of water in a low-flow toilet was inadequate to do the job when paired with the older plumbing, which had worked just fine with older toilets.

How to Adjust a Low-Flow Toilet

Fortunately, you do have some ways to adjust a low-flow toilet in your home so that it has an adequate amount of water to flush waste. How you adjust the water level of your toilet depends on the type of float you have in your toilet’s water tank, which is found in the back of the toilet. Here’s what you need to know about the different floats found in a toilet and how to adjust them.
Plunger/piston ballcock: Found in older toilets, a plunger/piston ballcock gets its name from its distinct shape and is comprised of a brass rod attached to a plunger or piston. To adjust this type of float, gently bend the brass flow upward to increase the water level in the tank. It’s important to make sure that the water level is below the tank overflow tube.
Brass diaphragm ballcock: Similar to the plunger/piston-style ballcock, a brass diaphragm ballcock uses a diaphragm as opposed to a piston and a float ball at the end of the brass rod to control water level. Just like with the plunger-style, bend the brass rod gently upwards to increase the height of the water in the tank, making sure the water doesn’t flow into the overflow tube.
Plastic diaphragm ballcock: The diaphragm ballcock also comes in a plastic version. Unlike the brass version, there is a screw you can adjust on the top of where the brass rod pivots as the tank fills. Turning the screw counterclockwise raises the water level in the tank. Just make sure that the water level is below the top of the tank’s overflow tube.
Float-cup fill valve: This fill valve is much different than previous ones and features a more compact design. With a float-cup fill valve, the water level is controlled by a plastic float attached to the fill shaft. You can raise or lower the float cup and change the water level by pinching the metal spring clip. This allows you to adjust the water level by raising it to make it higher and lowering it for less water.
Some float-cup fill valves also have a plastic screw mechanism that allows you to raise or lower the float in your low-flow toilet. When adjusting the water level, make sure it’s one inch below the top of the overflow tube.
Internal float fill valve: An internal float fill valve is similar to the float-cup fill valve, except that the float is hidden inside of the valve. Simply twist the top of the fill valve counterclockwise to unlock it. Then, move the fill valve to increase/decrease the water level. Once the water level is where you want it, twist the head clockwise to lock it back into place.
Floatless/pressure-activated fill valve: A floatless/pressure-activated fill valve uses a pressure-sensing mechanism to determine the water level in the water tank. To adjust this kind of fill valve, turn the screw at the top of the valve clockwise to raise the water level and counterclockwise to lower it. As with other fill valve types, the water needs to be below the top of the overflow tube.