How to Wire a Septic Pump Alarm

Hunker may earn compensation through affiliate links in this story.

Things You'll Need

  • Septic alarm with mounting hardware

  • Junction box with cover

  • Electrical conduit

  • Septic alarm float

  • Screwdriver

  • Two wire nuts for 12 AWG wire


Test wire connections by gently pulling on them. Test the alarm by physically lifting the alarm floats to its upright position. If installed correctly, the alarm will sound.


A junction box must not have a direct conduit to the septic tank. Gases from the septic tank could enter the junction box and create an explosive hazard.

Septic alarms alert homeowners of septic system problems.

Septic system alarms alert the homeowner when an imminent sewage back-up is likely. Inside the septic tank, a float switch tethered to a fixed position in the tank floats up and down with the liquid level. When the liquid level gets too high, a switch inside the float closes the alarm circuit, activating the alarm. Septic system installers bury two wires from the house to a new septic tank. One wire provides power to the pump, while the other wire is reserved for the septic pump alarm circuit. Septic system installers install the alarm float switch to the inside of the septic tank. The wiring of the float switch to the alarm circuit remains the homeowner's responsibility.

At the Tank

Step 1

Locate the alarm float wires and the alarm circuit wires running to the house. (They should have a label.)

Step 2

Push the wires through the electrical conduit and into the junction box.

Step 3

Hold the bare ends of the black wires together and insert the pair into a wire nut, twisting it until it is tight. Repeat with the white wire and the other wire from the float switch.

Step 4

Press all the wiring into the junction box and screw the cover into place.

In The Home

Step 1

Locate the alarm in a high traffic area close to the incoming septic tank alarm wires and an electrical plug-in.

Step 2

Insert the mounting screws through the mounting holes in the alarm's housing and screw into the wall.

Step 3

Connect the black wire from the septic tank alarm circuit to the positive terminal on the alarm. Connect the white wire to the negative terminal.

Step 4

Screw down the terminal lugs until they are snug.

Step 5

Insert the power plug for the alarm into the power receptacle.


Stephen Hasty

Stephen Hasty started writing in 2009. Covering technical articles and newsletters, his work has appeared in "The Kennebec Valley Plumbing Newsletter" and "Maine Leasing." Hasty holds a bachelor's degree from Saint Cloud State University, a real estate sales agent license and a master plumber license from the state of Maine.