Installing an Upflush Toilet

How to install an upflush toilet. Find tips and information on planning and running drain and vent lines, basic carpentry skills, connecting pipes, and more. From DIY Advice.


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, it has an electric pump that efficiently discharges waste up and away. A GFCI receptacle must be installed nearby.

Upflushing units usually are installed under or near the toilet. Most can serve a sink and a tub as well.

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.

Prestart Checklist

A day

Level, adjustable wrench, PVC saw, deburring tool, screwdriver, carpentry tools

Planning and running drain and vent lines, basic carpentry skills

Purchase a unit, draw a plan, and consult with a plumbing inspector to make sure the plumbing will meet code

Upflushing unit, PVC pipe and fittings, primer, cement, toilet

Step 1

This unit is designed to fit between 2x6 joists. It must rest on a stable, fairly level surface. If necessary, build a simple 2x2 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 2

Prepare the unit for the toilet: Install 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 3

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 4

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 5

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 6

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 7

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 8

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.

Comments (7)
mikecoxon1978 wrote:

basement toilet instalation

1/13/2017 04:57:33 AM Report Abuse
dschenk2 wrote:

The 4" piping on my up flush toilet shakes at the end of the discharge cycle. It acts like the hard closing of an air lock. My tank is in beneath the basement floor. Any thoughts?

1/8/2011 09:23:02 AM Report Abuse
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