The first and most critical step is to ensure your safety by completely disconnecting the sump pump from its power source. Unplug the pump's power cord from the wall outlet, which should be a GFCI outlet. If the pump is hardwired, locate the correct circuit breaker in your home's main electrical panel and switch it to the 'OFF' position. To be absolutely certain the power is off, use a non-contact voltage tester to check the cord or wiring. Once power is confirmed off, remove the lid from the sump pit to gain access.

Locate the check valve or rubber coupling on the vertical discharge pipe above the pump. A check valve prevents water from flowing back into the pit. Place a bucket nearby to catch water. Using a flathead screwdriver or a nut driver, loosen the two metal band clamps on the rubber coupling that connects the pump's pipe to the main drain line. Once loosened, you can gently pull the pipes apart. Be prepared for water to spill out from the section of pipe above the check valve.

With the plumbing disconnected, firmly grasp the old pump by its carrying handle. Do not lift it by the power cord or the float switch, as this can cause damage. Lift the pump straight up and out of the sump pit. It will be heavy and full of residual water and sludge. Immediately place the old pump into a large bucket or onto a prepared plastic sheet to prevent dripping dirty water onto your floor.

Before installing the new pump, take the opportunity to clean the sump pit. Use a wet/dry vac or a scoop to remove any gravel, mud, and debris from the bottom of the pit. Unpack your new sump pump and review the manufacturer's instructions. Take the new threaded male PVC adapter and wrap its threads with 3 to 4 layers of Teflon tape. Apply the tape in a clockwise direction as you face the open end of the fitting. This ensures the tape tightens as you screw the fitting in. Hand-thread the adapter into the pump's discharge port, then use channel-lock pliers to give it a final one or two turns until it's snug. Do not over-tighten, as this can crack the plastic housing.

Carefully lower the newly prepared pump into the center of the pit. Ensure the pump is sitting flat on the bottom and that its float switch has ample room to move up and down without hitting the pit walls. Measure and cut the vertical PVC pipe to the correct length to fit between the new pump's adapter and the existing discharge line, accounting for the height of the new check valve. It's best to install a new check valve. A new valve typically includes two rubber couplings and four clamps. Slide the clamps and couplings onto the pipe ends. Insert the check valve, making sure the flow-direction arrow points UP, away from the pump. Position the valve and couplings, then firmly tighten all four band clamps with a screwdriver or nut driver.

With the installation complete, it's time to test. Plug the pump's power cord back into the GFCI outlet. Use a hose or buckets to slowly pour water into the sump pit. As the water level rises, it will lift the float switch. When the float reaches its activation height, the pump should turn on with a hum. Watch as it quickly pumps the water out of the pit. The pump should shut off automatically as the float switch drops with the water level. During this test, carefully inspect all the connections, especially around the new check valve, for any signs of leaks.

Once you have successfully tested the pump and confirmed there are no leaks, you can finalize the installation. Neatly arrange the power cord, ensuring it is clear of the float switch's path of travel. Use plastic zip ties to secure the power cord to the side of the discharge pipe to keep it tidy and prevent it from getting tangled. Finally, place the lid securely back on top of the sump pit to complete the job.