A submersible pump sits fully underwater and pushes water up through a discharge hose or pipe. Whether you’re draining a flooded basement, emptying a pool, or supplying water from a well, the basic process is the same: lower the pump into water, connect a discharge line, plug it in, and let it run. The details that matter are choosing the right pump for the job, setting it up safely, and avoiding the handful of mistakes that burn out motors or kill performance.
Choosing the Right Pump for Your Job
Submersible pumps fall into a few broad categories, and using the wrong type leads to frustration. Sump pumps are built for permanent installation in a basement pit, where they automatically remove groundwater that collects around your foundation. They’re sturdier, handle higher capacities, and run in wet environments for long stretches. Utility pumps are portable and designed for temporary jobs: draining a hot tub, clearing water from a window well, or transferring water between tanks. They handle both clean and dirty water but aren’t meant for continuous-duty use.
Deep well pumps are a different animal entirely. These install hundreds of feet underground inside a well casing and push water up to your home’s pressure tank. Installing one typically requires two people and professional-grade splice kits for waterproof wiring. For most readers searching “how to use a submersible pump,” a portable utility pump or a sump pump is the more likely scenario, so that’s where the rest of this guide focuses.
Setting Up the Discharge Hose
The discharge hose is the single biggest factor in how well your pump performs. A hose that’s too narrow or too long creates friction that chokes flow rate. At 100 feet of length, a 1-inch hose can move roughly 62 gallons per minute, while a half-inch hose drops to about 10 gallons per minute. A 2-inch hose jumps to around 384 gallons per minute under the same conditions. Even at shorter lengths, undersizing the hose means your pump works harder and moves less water.
Match the hose diameter to the pump’s discharge port. If your pump has a 1.25-inch outlet, don’t reduce down to a garden hose unless you’re fine with a fraction of the rated flow. Use the shortest, straightest run you can. Every bend and every vertical foot the water has to climb adds resistance. Make sure the discharge end drains to an area where the water won’t flow back toward your foundation or into a neighbor’s yard.
When You Need a Check Valve
If your discharge line runs vertically (common in sump pits and wells), install a check valve on the pipe above the pump. Without one, every time the pump shuts off, the entire column of water in the pipe drains back down, forcing the pump to re-lift that water on the next cycle. This wastes energy and shortens the pump’s life. Most quality submersible pumps come with a built-in check valve at the discharge port. For vertical runs, place an additional valve no more than 25 feet above the water level. On very deep installations, add another check valve every 200 feet.
Electrical Safety
Water and electricity are a dangerous combination, so this step matters more than any other. Plug your pump into a GFCI-protected outlet. The National Electrical Code requires ground fault protection for submersible pumps, and for good reason: a fault in an underwater motor can energize the surrounding water. If you’re working near standing water, never handle the plug or cord with wet hands, and keep all electrical connections above the waterline.
Check the cord for nicks, cracks, or exposed wiring before every use. A damaged cord submerged in water is a shock hazard. If your pump is hardwired (as most permanent sump pumps are), make sure the circuit breaker is off before doing any work on the connections, and confirm the system is properly grounded.
Placing the Pump in Water
Lower the pump to the bottom of the water source, keeping it upright. Most submersible pumps pull water through an intake screen on the bottom or sides of the housing. If you set the pump on a muddy or silty surface, debris gets sucked into the impeller and either clogs the pump or wears it down. Place it on a flat, hard surface when possible. A paver or piece of plywood works well in a pinch.
Traditional submersible pumps need a minimum water depth of about 4 to 12 inches (10 to 30 cm) covering the motor to keep it cool. The motor relies on surrounding water for cooling, so running it in shallow water or dry conditions will overheat and destroy it within minutes. If you need to remove water down to a near-dry surface, low-level pumps exist that can operate in as little as 1 mm of water, but a standard pump will leave behind a puddle you’ll need to mop or wet-vac.
Running the Pump: Manual vs. Automatic
Portable utility pumps are typically manual. You plug them in, they run. You unplug them, they stop. Keep an eye on the water level and shut the pump off before it runs dry.
Sump pumps use a float switch to cycle on and off automatically. Three types are common:
- Tethered float: A buoyant ball on a cord that rises with the water level. These are the most common but also the most prone to problems. The tether can snag on the side of the pit or wrap around the pump, preventing it from activating.
- Vertical float: A ball that slides up and down a vertical rod. More reliable than tethered designs and less likely to get stuck. When water rises to a set point, the ball triggers the switch.
- Electronic switch: No moving parts. These use sensors to detect water level and activate the pump. They’re the most reliable option and often feature a piggyback plug design, meaning you plug the switch into the outlet, then plug the pump into the switch. This makes replacement simple.
If your float switch isn’t triggering at the right level, check for obstructions first. In a sump pit, debris, gravel, or even the discharge pipe can block the float’s movement. Tethered floats can sometimes be adjusted by shortening or lengthening the cord to change the activation point.
Clearing Air Locks
If your pump turns on but produces little or no water, or the flow sputters and surges, air may be trapped inside the pump housing or discharge line. This is called an air lock, and it’s one of the most common problems with submersible pumps. It happens when water levels drop below the intake, when there are small leaks in the suction line, or when pipes have a high point where air bubbles collect.
The simplest fix is the gravity method: find the highest water outlet connected to the system (an upstairs faucet, an outdoor hose bib) and open it fully. Turn the pump on and let it run. The air will work its way out through the open tap. Once the sputtering stops and water flows smoothly, close the tap. If that doesn’t work, some pumps have a bleed valve or priming screw on the housing. Turn the pump off, open the valve to release trapped air, pour water into the priming port until it’s full, close the valve, and restart. For persistent air locks in permanent installations, an automatic air vent installed at the highest point in the piping can prevent the issue from recurring.
Maintenance That Extends Pump Life
Submersible pumps are designed to be low maintenance, but “low” doesn’t mean “none.” A few regular checks make the difference between a pump that lasts two years and one that lasts ten.
Clean the intake screen periodically. Pull the pump out and remove any debris, sediment, or mineral buildup around the screen and housing. A soft brush and mild detergent are enough for the exterior. While you have the pump out, inspect the impeller for cracks, missing vanes, or heavy wear. A damaged impeller reduces flow and puts strain on the motor. If it’s visibly worn, replace it before the pump fails during a storm.
Check all wiring connections for corrosion or looseness, especially where the cord meets the pump body. Inspect the discharge pipe and check valve for buildup or blockages. Test the float switch by manually lifting it to confirm the pump activates. For sump pumps, pour a bucket of water into the pit once or twice a year to verify the full cycle: the pump should kick on, evacuate the water, and shut off cleanly. If it hesitates, runs continuously, or short-cycles, something needs attention before the next heavy rain.