The basic path water takes from the ground to your tap

A well pump sits at the bottom of a hole drilled into the ground, where it pulls water up through a pipe and into your home's plumbing system. The pump does not create water — it creates pressure that overcomes the weight of the water column above it and pushes water upward against gravity. Most residential well pumps are submersible, meaning they sit underwater inside the well casing, or jet pumps, which sit above ground and use suction to draw water up from shallow wells.

The pump runs on electricity. When you turn on a faucet, the drop in water pressure inside your home's tank triggers a pressure switch that tells the pump to start. The pump runs until pressure builds back up to a set level — usually between 40 and 60 pounds per square inch — then shuts off automatically. This cycle repeats every time you use water.

Key Takeaways

  • Submersible pumps sit underwater at the bottom of the well and push water up through a single pipe; jet pumps sit above ground and pull water up through suction, and work only for shallow wells under 25 feet deep.
  • A pressure tank stores water and maintains steady pressure so the pump does not start and stop with every faucet turn.
  • The pump motor runs on electricity and is controlled by a pressure switch that turns it on when pressure drops and off when it reaches the set level.
  • Check valve prevents water from flowing backward down the pipe when the pump stops, and a pitless adapter keeps the well opening above ground level to prevent contamination.

How a submersible pump works underground

A submersible pump is a long cylinder that fits inside the well casing — the metal or plastic pipe that lines the hole. The pump sits on the bottom or near it, surrounded by water. Inside the pump, an electric motor turns a shaft connected to an impeller, which is a wheel with curved blades. As the impeller spins, it forces water outward and upward into a discharge pipe that runs to the surface.

The pump does not suck water up like a straw. Instead, it creates a pressure difference: the spinning impeller pushes water away from the center, which lowers pressure at the center and allows more water to flow in from the well. This happens in stages — most residential submersible pumps have multiple impellers stacked inside the same cylinder, each one raising the pressure a little more. By the time water reaches the top, the pressure is high enough to fill your tank and push water through your pipes.

A single electrical cable runs down the well casing to power the motor. This cable is the pump's only connection to the surface. The pump itself is sealed and waterproof, so it can sit submerged indefinitely without damage. Water cools the motor as it runs, so submersible pumps are less likely to overheat than above-ground pumps.

How a jet pump works above ground

A jet pump sits in your basement, garage, or pump house — anywhere above ground near the well. It uses a different method: instead of pushing water up from below, it pulls water up using suction. A jet pump has two pipes running down into the well. One pipe, called the drive pipe, carries pressurized water down. The other, called the return pipe, brings water back up.

Inside the pump, an electric motor spins an impeller that pressurizes water and sends it down the drive pipe. At the bottom of the well, the pressurized water shoots through a small opening called a jet, which creates a vacuum. This vacuum sucks water from the well into the return pipe, and the water flows back up to the surface. The pump then separates the incoming water from the pressurized water and sends the incoming water to your tank.

Jet pumps work only for shallow wells — typically 25 feet deep or less — because suction has a physical limit. The deeper the well, the harder it is to create enough suction to pull water up. For this reason, jet pumps are less common in areas where wells are deep. They also require a check valve at the bottom of the well to prevent water from draining back down when the pump stops.

The pressure tank and how it keeps water flowing

A pressure tank is a metal or fiberglass container that stores water and maintains pressure in your plumbing system. Without a tank, the pump would have to start every time you turned on a faucet — even for a few seconds of water — which would wear out the pump quickly and waste electricity.

The tank is divided into two chambers by a rubber bladder or diaphragm. One chamber holds water; the other holds compressed air. As water fills the tank, it compresses the air. When you open a faucet, the compressed air pushes the water out, and pressure drops. Once pressure falls to the cut-in point — usually 40 psi — the pressure switch signals the pump to start again. The pump runs until pressure rises to the cut-out point — usually 60 psi — then stops.

A typical residential tank holds 40 to 80 gallons. The size matters: a larger tank means the pump runs less often, which extends its life. A smaller tank means the pump cycles more frequently. Most homeowners with a 3-bedroom house use a 40 or 50-gallon tank, but the right size depends on how much water you use and how deep your well is.

Check valves and why water does not flow backward

A check valve is a one-way valve installed on the discharge pipe just above the pump. It allows water to flow upward toward your home but prevents water from flowing backward down the pipe when the pump stops. Without a check valve, water in the pipe would drain back into the well, and the pump would have to refill the pipe every time it starts — wasting energy and putting extra strain on the motor.

Check valves are especially important in deep wells, where the weight of a tall column of water creates significant downward pressure. In shallow wells, the effect is smaller but still present. Most well systems have at least one check valve, and some have two — one near the pump and one near the pressure tank — for extra protection.

Over time, check valves can stick or leak. A leaking check valve allows water to drain back into the well overnight, so the pump has to work harder the next morning to refill the pipe. If you notice the pump running longer than usual after sitting idle, a failing check valve may be the cause.

The pitless adapter and keeping the well opening sealed

A pitless adapter is a fitting that allows the discharge pipe to exit the well casing below ground level, rather than through the top of the well. This keeps the well opening above ground, where it can be sealed with a sanitary cap. A sealed well opening prevents contamination from surface water, insects, and debris.

Without a pitless adapter, the discharge pipe would have to come up through the well casing and exit at the top, leaving an opening that could allow contaminants to enter. The pitless adapter solves this by routing the pipe horizontally underground, usually to a point a few feet away from the well, where it comes back up to the surface and connects to your home's plumbing.

The adapter sits at the bottom of the well casing and must be installed during well construction or during a major repair. If your well does not have a pitless adapter, the well opening should be sealed with a sanitary cap to reduce contamination risk.

Electrical controls and the pressure switch

The pressure switch is an electrical device that monitors the pressure in your tank and tells the pump when to start and stop. It is mounted on the pressure tank or on a nearby pipe and is connected to the pump motor through a control box.

When pressure inside the tank drops to the cut-in point — usually 40 psi — the switch closes an electrical circuit and sends power to the pump motor. The pump runs and pushes water into the tank, raising the pressure. When pressure reaches the cut-out point — usually 60 psi — the switch opens the circuit and cuts power to the pump. The pump stops, and the compressed air in the tank pushes water out through your faucets until pressure drops again.

Most pressure switches are adjustable, so you can change the cut-in and cut-out points if needed. Raising the pressure range means the pump runs less often but stores more water; lowering it means the pump runs more often but uses less tank space. The standard 40–60 psi range works for most homes, but some systems use 30–50 psi or 50–70 psi depending on the number of bathrooms and water usage.

Frequently Asked Questions

Why does my well pump run more often in summer than winter?

Warmer water takes up slightly less space than cold water, so the tank pressure drops faster as you use water. Additionally, most households use more water in summer for outdoor activities, lawn watering, and showers. Both factors cause the pump to cycle more frequently.

Can a well pump run dry if the water table drops?

Yes. If the water level in the well falls below the pump intake, the pump will run but produce no water. A dry-run switch can shut off the pump automatically to prevent damage to the motor. If your well runs dry, you may need to have the pump lowered deeper into the casing or wait for the water table to recover.

What does it mean if the pump is short-cycling?

Short-cycling is when the pump starts and stops very frequently — sometimes every few minutes — even when you are not using water. This usually means the pressure tank has lost its air charge, the check valve is leaking, or the pressure switch is set incorrectly. A leaking check valve is the most common cause and should be repaired soon to avoid pump damage.

How long does a well pump usually last?

A submersible pump typically lasts 8 to 15 years, depending on water quality, usage, and maintenance. Jet pumps often last 7 to 10 years. Hard water, sand in the well, and frequent short-cycling all shorten pump life. Regular maintenance — such as checking the pressure tank air charge and inspecting the check valve — can extend the pump's lifespan.

Do I need to do anything to maintain my well pump?

Check the pressure tank air charge once a year by tapping on the tank — the top should sound hollow and the bottom should sound full of water. Have the pressure switch and check valve inspected every few years. Keep the well opening sealed and free of debris. If you notice changes in water pressure, flow rate, or pump noise, have the system inspected by a well contractor.