A well pump moves water from below ground to your house by creating pressure that forces it upward

A well pump sits at the bottom of a well shaft and pulls water from the aquifer below, then pushes it up through a pipe to your home. The pump does not suck water the way a straw does — instead, it creates a pressure difference that allows atmospheric pressure to push water up the pipe. Most residential wells use one of two types: a submersible pump that sits underwater inside the well, or a jet pump that sits above ground and uses suction to draw water up. The choice depends on how deep your well is and how much water your household needs.

Without a pump, water would stay in the ground. The pump is the only reason water reaches your kitchen sink, shower, and toilet. Understanding how it works helps you recognize when something goes wrong and why maintenance matters.

Key Takeaways

  • A well pump creates pressure that forces underground water upward through a pipe to your home, rather than sucking it up like a straw.
  • Submersible pumps sit inside the well and work best for deep wells; jet pumps sit above ground and work for shallower wells.
  • The pump fills a pressure tank that stores water and keeps pressure steady so water flows when you turn on a faucet.
  • A pressure switch tells the pump when to turn on and off based on how much water is stored in the tank.
  • Most residential well pumps last 8 to 15 years before they need replacement.

How pressure moves water upward

Water cannot flow uphill on its own. A well pump solves this by creating pressure — a force that pushes water from the low point (the aquifer) to the high point (your home). The pump has an electric motor that spins an impeller, a wheel with curved blades. As the impeller spins, it flings water outward and upward, creating an area of low pressure behind it. Atmospheric pressure from above pushes more water into that low-pressure space, and the cycle repeats many times per second.

This pressure builds up inside the pump and the pipe. Once the pressure is strong enough, it can push water all the way up from depths of 25 feet, 100 feet, or even deeper, depending on the pump's power. The water exits the top of the well and flows into your home's plumbing system.

Submersible pumps for deep wells

A submersible pump is sealed in a metal cylinder and lowered into the well on a cable, where it sits underwater at the bottom. The motor and impeller are both inside the waterproof housing. When the pump runs, it pushes water up through a pipe that runs alongside the cable, all the way to the surface and into your home.

Submersible pumps are the most common choice for residential wells deeper than 25 feet. They work well because they do not have to fight gravity as hard — the water is already close to the pump. They are also quieter than jet pumps because they operate underwater, which muffles the sound. The downside is that if the pump fails, you have to pull it out of the well to repair or replace it, which is labor-intensive and expensive.

Jet pumps for shallow wells

A jet pump sits in your basement or a utility room above ground. It uses a motor to spin an impeller that creates suction, pulling water up from the well through a pipe. The pump can only pull water up about 25 feet effectively, so jet pumps work best for shallow wells. They are cheaper to install and easier to repair because they sit where you can reach them.

Jet pumps are noisier than submersible pumps because the motor and impeller operate in air rather than water. They also use more electricity to do the same job. For wells deeper than 25 feet, a jet pump loses efficiency and may not pull water up at all, which is why submersible pumps dominate in areas with deeper aquifers.

The pressure tank stores water and keeps flow steady

The pump does not send water directly to your faucets. Instead, it fills a pressure tank — a large metal or plastic container that holds water under pressure. The tank has two chambers: one holds water, and the other holds compressed air. As the pump pushes water in, the air compresses, building pressure inside the tank.

When you turn on a faucet, water flows out of the tank rather than directly from the pump. This is why water comes out when ready instead of waiting for the pump to start. The tank also smooths out the pressure so your water pressure stays steady instead of pulsing on and off. As the tank empties, the pressure inside drops. When it falls below a set level, a pressure switch signals the pump to turn on and refill the tank.

A typical pressure tank holds 20 to 80 gallons, depending on your household size. Larger households need larger tanks so the pump does not have to run constantly. If the tank is too small, the pump cycles on and off frequently, which wears it out faster.

The pressure switch controls when the pump runs

A pressure switch is a small device that monitors the pressure inside the tank. It has two settings: a lower pressure threshold and an upper one. When pressure drops to the lower threshold — usually around 40 pounds per square inch — the switch flips on and tells the pump to start. The pump runs and pushes water into the tank until pressure reaches the upper threshold, usually around 60 pounds per square inch. Then the switch flips off and the pump stops.

This on-off cycle repeats throughout the day as you use water. The pressure switch prevents the pump from running constantly and also prevents pressure from getting so high that it damages pipes or fixtures. If the switch fails, the pump may run nonstop or not run at all, which is a sign you need a repair.

Check valves prevent water from flowing backward

A check valve sits between the pump and the pressure tank. It allows water to flow in one direction only — from the pump toward the tank. If pressure in the tank drops, the check valve closes and prevents water from flowing backward down into the well. Without this valve, water would drain out of the tank and back down the well shaft every time the pump stops, and you would lose pressure.

Check valves are straightforward and reliable, but they can stick or fail over time, especially if sediment or mineral buildup clogs them. A failing check valve causes the pump to lose its prime — the water that fills the pump and pipe. When a pump loses its prime, it cannot pull water up anymore and has to be reprimed by hand or by a technician.

How long well pumps last and when they fail

Most residential well pumps last between 8 and 15 years. Submersible pumps tend to last longer because they operate in a stable, cool environment underwater. Jet pumps wear out faster because they work harder and run hotter. The lifespan also depends on water quality, how often the pump runs, and whether it receives regular maintenance.

A pump fails when the motor burns out, the impeller wears down, or internal seals leak. Signs of failure include low water pressure, the pump running constantly without building pressure, water that spurts instead of flowing smoothly, or the pump making grinding or squealing noises. If your pump is more than 10 years old and shows any of these signs, replacement is usually more cost-effective than repair.

Regular maintenance extends pump life. This includes checking the pressure tank for rust or leaks, testing the pressure switch to make sure it turns the pump on and off at the right pressures, and having the well water tested for sediment or minerals that can clog the pump. If sediment is present, a sediment filter before the pressure tank can protect the pump.

Frequently Asked Questions

Why does my well pump run but no water comes out?

The pump has likely lost its prime — the water that fills the pump and pipe. This happens when the check valve fails, the pipe develops a leak, or the water level in the well drops below the intake. You can try repriming the pump by pouring water into the top of the well or the pump itself, but if it does not work, a technician needs to diagnose whether the check valve, pipe, or pump itself is the problem.

What is the difference between a 1 horsepower and 1.5 horsepower pump?

A larger horsepower pump pushes water faster and can handle deeper wells or higher water demand. A 1 horsepower pump is adequate for most small households with shallow to moderate wells. A 1.5 horsepower pump is needed for larger households, deeper wells, or homes that use a lot of water at once. Oversizing the pump wastes electricity; undersizing it means slow water pressure and frequent cycling.

Can I install a well pump myself?

Installing a well pump requires dropping equipment down a deep shaft, connecting electrical wiring safely, and setting up pressure switches and check valves correctly. Most homeowners should hire a licensed well contractor. Mistakes can damage the pump, contaminate the well, or create electrical hazards. The cost of professional installation is worth the safety and reliability.

How do I know if my pressure tank needs replacement?

Pressure tanks rust from the inside out and eventually leak. If you see rust on the outside, the inside is likely worse. If the pump runs constantly but pressure stays low, the tank may have lost its air charge or developed a leak. A technician can test the tank and tell you whether it can be repaired or needs replacement.

What happens to my water if the power goes out?

The pump stops running, but water remains in the pressure tank. You can use that stored water until the tank empties — usually enough for a few hours of normal use. Once the tank is empty, no more water flows until power returns and the pump restarts. A backup generator can keep the pump running during an outage.