Installing a dual-flush toilet goes a long way to conserve water and reduce your utility bills. This modern plumbing fixture offers two flushing options: a lower-volume flush for liquid waste and a full-volume flush for solid waste. In this guide, we walk you through the process of installing a dual-flush toilet, from removing the old toilet to setting up the new water-saving model. This Old House plumbing and heating expert Richard Trethewey demonstrates installation in the video above.
Tools and Materials Needed to Install a Dual-Flush Toilet
- Adjustable wrench
- Carbide-tipped masonry drill bit
- Closet bolts
- Cordless drill/driver
- dual-flush toilet kit
- Flexible water supply line
- Level
- Mounting blocks
- Open-ended wrench
- Plumber’s tape
- Putty knife
- Screwdriver
- Twist drill bit
- Wax ring
Removing the Old Toilet
Before installing your new dual-flush toilet, you’ll need to remove the existing fixture. Here’s how to do it:
- Turn off the water supply to the toilet and flush to empty the tank.
- Disconnect the water supply line from the toilet.
- Remove the nuts securing the toilet to the floor.
- Lift the toilet off the closet flange and set it aside.
- Use a putty knife to scrape away the old wax seal from the closet flange.
Installing the New Dual-Flush Toilet
With the old toilet removed, you’re ready to install the new dual-flush model. This process involves several steps, from preparing the mounting surface to connecting the water supply.
Preparing the Mounting Surface
- Insert new closet bolts into the slots in the closet flange.
- Place the plastic mounting flange over the closet flange.
- Use the paper template provided with the toilet to mark the screw-hole locations for the mounting blocks.
- For tile floors, use a carbide-tipped masonry drill bit to create pilot holes.
- Switch to a twist drill bit to bore screw-pilot holes into the wood subfloor.
- Securely screw the two mounting blocks to the floor.
Setting the Toilet Base
- Press a wax seal onto the plastic mounting flange and set it on top of the closet flange.
- Add washers and hex nuts to the closet bolts, then tighten with an open-end wrench.
- Carefully lower the new toilet into place, ensuring it fits over both mounting blocks.
- Secure the toilet base by screwing through it into the mounting blocks.
- Conceal the screw heads with the provided chrome caps for a polished look.
Installing the Tank
- Remove the flush valve from inside the toilet tank.
- Connect the flexible water supply line to the underside of the tank.
- Carefully set the tank onto the bowl and tighten the two bolts.
- Reinstall the flush valve inside the tank and connect the refill tube.
Connecting the Water Supply to Dual-Flush Toilet
The final step in installing your dual-flush toilet is connecting the water supply. This process ensures your new toilet will function efficiently.
- Connect the water supply line to the shut-off valve.
- Open the valve to fill the toilet tank.
- Flush the tank several times to check for leaks and proper operation.
- Make any necessary adjustments to ensure optimal performance.
How Dual-Flush Toilets Work
Dual-flush toilets are designed to conserve water by offering two flushing options. This technology can significantly reduce water usage in your home, leading to lower utility bills and a smaller environmental footprint.
Dual-flush toilets typically feature two buttons or a split flush lever on top of the tank. One button releases a smaller amount of water (usually around 0.8–1.1 gallons) for liquid waste, while the other releases a full flush (about 1.6 gallons) for solid waste. This design allows users to choose the appropriate flush volume for their needs, potentially saving thousands of gallons of water per year.
Dual-Flush Toilet Maintenance and Troubleshooting
Regular maintenance keeps your dual-flush toilet functioning properly. Here are some tips to help you maintain your new toilet and troubleshoot common issues:
- Clean the toilet regularly to prevent mineral buildup and stains.
- Check the flush buttons or lever periodically to ensure they’re working correctly.
- Inspect the fill valve and flapper for signs of wear or damage.
- If you notice any leaks or unusual noises, address them promptly to prevent water waste and potential damage.
Addressing Common Issues
Some common problems with dual-flush toilets include constant running, weak flushes, or incomplete bowl clearing. Most of these issues can be resolved by adjusting the fill valve or flapper or by cleaning the flush mechanism. If problems persist, consult a professional plumber.
