How to Install an Upflush Toilet

If you're remodeling to add a bathroom to your basement, consider an upflush toilet, which uses an electric pump to get rid of waste.

Installing a new bathroom in a basement can be a major undertaking. The concrete floor must be broken into and drainpipes installed, then new concrete must be poured.

An upflushing unit makes the job much easier. Instead of using gravity to drain, an upflushing toilet has a heavy-duty pump activated by a float and switch. When the lower portion of the tank fills, the pump turns on, forcing waste up through the 2-inch drain. A 3-inch vent is required. Make sure the vent and drain conform to local plumbing codes.

Some upflushing units, especially those installed in the '70s and '80s, were unreliable and needed frequent repairs. Newer units are more dependable. Ask a plumbing supplier about the track record of the model you are considering. Make sure the unit's pump is powerful enough to send wastewater the required distance to the house's drain. 

An upflushing unit has a heavy-duty pump activated by a float and switch. When the lower portion of the tank fills, the pump turns on, forcing waste up through the 2-inch drain. A 3-inch vent is required. Make sure the vent and drain conform to local plumbing codes.

You'll need roughly a day to install the toilet. Get started by purchasing a unit, drawing a plan, and consulting with a plumbing inspector to make sure the plumbing will meet code.

  • Working Time 10 Hours
  • Start to Finish 1 Week
  • Difficulty         Projects Kind of Hard
  • Involves Plumbing Skills

What you need


  • Wheelbarrow
  • Spade
  • Level
  • Adjustable wrench
  • Garden hose
  • Bucket
  • Screwdriver
  • Hammer
  • Wrench


  • 2x6 joists
  • Sand-mix hydraulic concrete
  • Iron support flange
  • Toilet mounting bolts
  • Float switch
  • Discharge pipe
  • Drainpipe
  • GFCI receptacle
  • Rubber flange
  • 3-inch PVC vent pipe
  • Liquid soap
  • Backflow device
  • 2-inch PVC drainpipe
  • Subfloor
  • Subfloor fasteners
  • Purchased access panel
  • Wax ring
  • Upflush toilet
  • Stop valve

How to do it

Step 1 Check Depth

Before you choose a model and begin installation, determine what type of upflush toilet you'll need based on distance from the sewer line. A macerating toilet is useful if a bathroom will be well below the sewer line (as much as 12 feet) or if pipes must travel a long distance (up to 150 feet) before connecting with the main sewer line. A macerating toilet has a rotating blade that grinds waste before pumping it away. Macerating units have smaller discharge and drainpipes. The flush cycle normally takes 15 to 18 seconds.

A macerating unit must be connected to a horizontal outlet toilet. Some manufacturers combine a toilet and pump. You can choose between stand-alone macerating toilets and units with connections for a tub/shower and a sink. (With either type the tub/shower must be raised to facilitate drainage.)

Step 2 Make Base

This unit is designed to fit between 2x6-inch joists. It must rest on a stable, fairly level surface. If necessary, build a simple 2x2-inch frame, mix and pour sand-mix hydraulic concrete, and set the unit in the concrete. Level in both directions. Allow the concrete to cure before proceeding.

Step 3 Install Support Flange

Prepare the unit for the toilet by installing the iron support flange. Make sure that the toilet mounting bolts are in the correct positions and are long enough for mounting the toilet.

Step 4 Install Pump

Assemble the float switch. Install the discharge pipe. Place the pump in the tank and mount the float switch. Before sealing the unit, make sure the pump works. Attach a garden hose to a water supply and run it into the flange hole.

Step 5 Discharge Extra Water

Connect the discharge to a drainpipe leading to a bucket or floor drain. Tape the temporary drainpipe joints—the pump is forceful. Plug the unit into a GFCI receptacle. Slowly fill the tank with water. The pump should come on and discharge water once it reaches the correct level.

Step 6 Install Vent Pipe

Insert the rubber flange provided and insert 3-inch PVC vent pipe to the unit. (It's a tight fit; liquid soap helps.) Run the vent to the main stack. Be sure to configure the vent and drain in a code-approved manner.

Step 7 Install Backflow Device

Connect the discharge pipe to the backflow device to ensure that wastewater will not flow back into the unit. (Be sure to install it with the correct end up—it is clearly marked.) Connect a 2-inch PVC drainpipe to the discharge unit and run it toward the house's drain in a code-approved manner.

Step 8 Connect Pipes

Connect the drain and vent pipes to the house's system. Plug the unit into a GFCI receptacle within reach from the access panel. Install the supply line. Install the subfloor and walls, being careful not to puncture the tank with any fasteners.

Step 9 Install Toilet

Finish the floor and walls and install the access panel. Install the toilet onto a wax ring where the bowl rests on the upflush unit. Connect the toilet to a cold water supply line with a stop valve.

Step 10 Connect Other Features

Additional plumbing fixtures—usually a tub/shower and a sink—can be connected to an upflush unit. Drainpipes for these fixtures must flow down to the upflush unit.

This does not pose a problem for the sink, because its drain is usually 16 inches above the floor. The tub, however, usually must be raised so the drain line can flow down to the upflush unit. One solution is to rest the tub on a shallow platform made of 2x4s and plywood. Vent pipes must be run in the standard manner .

Most manufacturers supply an extra flange for hooking up a tub/shower and sink drain to the tank. Follow the manufacturer's specifications for cutting the access hole for the drain.

RectangleCreated with Sketch. Rectangle Copy 3Created with Sketch.


Be the first to comment!

Better Homes & Gardens may receive compensation when you click through and purchase from links contained on this website.