Installing a toilet below grade is a manageable Do-it-yourself (DIY) project for many homeowners with some plumbing know-how looking to add a bathroom to their basement. While traditional plumbing methods may not work in this situation, modern technology offers some innovative solutions. This Old House plumbing expert Richard Trethewey shows how to install a basement toilet using a macerator unit, demonstrating how to overcome the challenges of below-grade plumbing.
Understanding Below-Grade Toilets
Below-grade toilets are designed to function in spaces where traditional gravity-fed plumbing systems are not feasible. These systems are essential for basement bathrooms or other areas where the toilet is located below the main sewer line.
How Below-Grade Toilets Work
Unlike standard toilets that rely on gravity to flush waste down through the floor, below-grade toilets use a macerator unit to grind waste and pump it up and out. This system allows for toilet installation in areas where conventional plumbing would be impossible or expensive. The key component, the macerator unit, sits behind the toilet and contains a pump that grinds up solid waste. The ground waste is then pumped through a small-diameter pipe, which can be routed up walls and across ceilings to connect with the main sewer line. This configuration makes it possible to install a bathroom virtually anywhere in the home.
Benefits of Below-Grade Toilets
Installing a below-grade toilet system offers several advantages:
- Flexibility in bathroom location
- Cost-effective alternative to major plumbing renovations
- Ability to add bathrooms in basements or other challenging spaces
- Minimal disruption to existing structures
Homeowners can essentially transform underutilized spaces into functional bathrooms, adding convenience and value to their properties.
Required Tools and Materials for Below-Grade Toilets
To install a below-grade toilet, you’ll need the following items:
- Macerator unit
- Specialized toilet designed for below-grade use
- PVC pipes and fittings
- Nut driver
- Drill/driver
- 5/16-inch drill bit
- Stainless steel clamps
- Brass lag screws
- PVC primer and cement
- Water supply line
Installing the Macerator Unit for a Below-Grade Toilet
The macerator unit is the heart of the below-grade toilet system. Proper installation is crucial for the system’s functionality and longevity.
Planning the Layout
First, carefully plan the layout of your new bathroom, considering the placement of the toilet, sink, and any other fixtures. Ensure that the macerator unit can be properly positioned behind the toilet and that there’s a clear path for the discharge pipe to reach the main sewer line. Measure twice to avoid any costly mistakes.
Connecting the Drain Lines
Next, connect the lavatory drain line to the macerator unit using PVC pipe and fittings. Prime and cement the connections to ensure a watertight seal. Then, connect the discharge pipe from the macerator unit to the main drain pipe that leads to the sewer line. This step ensures proper waste management and prevents leaks.
Securing Connections
Use a nut driver to tighten the stainless steel clamp connecting the PVC lavatory pipe to the macerator unit. This ensures a secure, leak-free connection. Tighten the discharge adapter on top of the macerator unit into place using the nut driver as well. Another vital connection is the stainless steel breeze clamp for the lavatory drain, which should be tightened securely.
Installing the Vent Pipe
Connect the PVC vent pipe from the macerator unit to the existing vent stack. Proper venting is essential for the system to function correctly and prevent odors from entering the living space. This step ensures that the air can circulate properly, maintaining system efficiency.
Setting the Below-Grade Toilet
With the macerator unit in place, you can install the specialized below-grade toilet. This part of the process involves securing the toilet and making necessary connections to ensure it functions smoothly.
Positioning and Marking
Set the toilet in its intended location and mark the mounting holes on the floor. This step ensures the toilet is properly secured and won’t move. Accurately mark these spots for a sturdy installation.
Drilling and Securing
Move the toilet aside and drill pilot holes into the floor at the marked locations. Then, set the toilet back into place and secure it to the floor using the provided brass lag screws. This step is particularly important for below-grade toilets, as they don’t have the benefit of a traditional closet flange for stability. The screws must be tightened adequately to prevent any movement.
Connecting to the Macerator
Connect the toilet to the discharge pipe on the macerator unit. Use the provided rubber accordion-style gasket to create a flexible, watertight seal. Secure this connection with a stainless steel clamp, tightening it with the nut driver. Ensuring all connections are tight and secure prevents leaks or malfunctions.
Finalizing the Below-Grade Toilet Installation
The final steps ensure that your new below-grade toilet is fully functional and properly connected to your home’s plumbing system. These steps include connecting the water supply and testing the system to ensure everything works as expected.
Connecting the Water Supply
Attach the water supply line to the toilet’s fill valve. Open the shut-off valve to allow water to fill the tank. Double-check all connections for leaks. Make sure the tank is securely fastened and that all joints are watertight. This step ensures that the toilet fills correctly and avoids any water damage.
Testing the System
Once everything is connected, flush the toilet to test the system. Listen for the macerator unit to activate and ensure that it’s functioning properly. Check all connections again for any signs of leaks or issues. This step confirms that everything is working as it should.
Run multiple flushes to verify that the system consistently performs well. Address any abnormal sounds or malfunctions immediately to ensure the toilet’s longevity. Additionally, make sure the venting is efficient to prevent any odor issues.
Maintaining Your Below-Grade Toilet
Regular maintenance keeps your below-grade toilet system in optimal condition. Routine checks can prevent major issues and prolong the lifespan of your system.
Regular Inspections
Regularly check the macerator unit, connections, and venting system. Look for any signs of wear or potential leaks. Early detection of issues can save time and money in the long run. Make it a habit to inspect these components at least once a month.
Cleaning and Servicing
Follow the manufacturer’s recommendations for cleaning and servicing the macerator unit. Regular cleaning prevents clogs and ensures efficient operation. Have the unit serviced by professionals as recommended by the manufacturer.
Handling Repairs
Address any repairs immediately to avoid costlier problems. Whether it’s a minor leak or a malfunctioning macerator, early repairs can prevent significant damage and costly fixes. Ensure that any repairs are conducted using quality parts and proper techniques to maintain the system’s integrity.
