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Toilets use much more water than you think they do. Homeowner Joel Grimm found his family used about 50 gallons of water per day just on flushes. “Every time we hit this tank lever,” says This Old House plumbing and heating expert Richard Trethewey, “the full contents of that tank leaves—it’s 3 1/2 gallons—and goes down through the bowl.” All those full flushes, and not many other options, sent Grimm’s water bill to a sky-high $1,000 per year.
You could save money by installing a new low-flow toilet, but cheaper and simpler options exist. Grimm decided to purchase a dual-flush system that costs about $30 to $40 and takes an hour or two to install. With a simple push of a button, he can choose between a full flush for solid waste and a partial 1-gallon flush for liquid waste.
Determined to help Grimm keep more money in his pocket, Trethewey demonstrates how a dual-flush system works and how to install one on your own toilet.
What You Need To Install a Dual Flush System
Dual flush systems come in special conversion kits compatible with different toilet models. Most are designed to work with standard toilets, but you should check the product specifications carefully before you buy one. Look for a kit that includes each of these components:
- Adjustable fill valve
- Dual flush valve
- Installation hardware
- Push-button actuator
You should also have the following tools and materials on hand for the installation:
- Adjustable pliers
- Bucket
- Screwdriver
- Towel or sponge
Safety Precautions When Installing a Dual-Flush System
This project doesn’t involve complex plumbing work, but you should still take some basic safety measures to protect yourself. Turn off the water supply to your toilet before you start, and hold the flush lever down to empty water out of the tank. You may want to wear gloves to keep your hands clean when dealing with a dirty toilet tank.
The Dual-Flush System Installation Process
Follow these steps to convert your toilet to a dual flush system:
Installing the Dual Flush Valve
Start by disconnecting the old flapper from the bottom of the tank and disconnecting the chain from the tank lever. Remove the lever by turning the nut clockwise. “It’s one of the few times in plumbing where it’s not righty-tighty, lefty-loosey,” Trethewey says.
The new dual flush valve sits where the flapper used to be. The blue gasket sits at the bottom to make a permanent seal. Connect the bracket on the side of the valve to the tank’s overflow tube. The bracket has a cable tie to secure the connection, but don’t tighten it yet.
Attaching the Push-Button Actuator
The push-button actuator replaces your old flush lever. To connect it to the tank, begin by detaching the button assembly from the rest of the actuator. Then, unscrew the rear nut of the button assembly, insert the threaded portion through the hole in the tank lid, and put the nut back on. The smaller button for partial flushes should be on top. Once you’ve adjusted the button positions, reconnect the rest of the actuator behind the nut. Tighten up the cable tie on the overflow tube bracket.
Adjusting the Fill Valve
Next, turn your attention to the toilet’s fill valve. This valve brings the right amount of water into the tank and refills the bowl with enough water for the next flush. Since less water leaves the bowl for a half flush, the fill valve won’t keep the bowl as full since it’s not tripped for as long.
Dual flush system manufacturers sometimes make fill valves designed for both half and full flushes. Install the new fill valve following the manufacturer’s instructions, then adjust the float so the tank fills to the proper level. Connect the refill tube to both the fill valve and the overflow tube.
Turn the water supply back on and let the tank fill back to 3 1/2 gallons. Do a test full flush, then a test half flush, and check the water level in the bowl afterward. Make fine-tuning adjustments to the fill as necessary.
Troubleshooting Common Issues With Dual-Flush Systems
Even with careful installation, you may encounter some issues.
Insufficient Bowl Refill
If the bowl doesn’t refill properly after flushing, adjust the fill valve to increase water flow to the bowl. Keep flushing and adjusting until the water reaches the correct height. If that doesn’t work, check the refill tube to make sure it’s properly connected and not kinked.
Leaks or Drips
For persistent leaks, check to make sure the flush valve gasket is properly placed. You should also inspect the tank-to-bowl gasket for damage or wear and verify all other connections are tightly sealed.
Inconsistent Flush Performance
If flush performance is inconsistent, you may need to adjust the dual-flush mechanism according to the kit’s instructions. Check that the push-button activator is properly and securely connected to the flush valve. It may also help to clean rim jets and get rid of debris that can gum up the flush valve’s mechanism.
