The Basic Path Water Takes From Underground to Your Tap

A well pump pulls water from underground and pushes it up to your house. The pump sits either inside the well or above ground next to it. When you turn on a faucet, the pump starts working—it draws water down through a pipe, pressurizes it, and sends it through another pipe to your home's plumbing system. The whole cycle repeats each time you use water, and a pressure tank stores some water so the pump does not have to run constantly.

The three main parts that make this work are the pump itself (which creates suction and pressure), the pressure tank (which holds water under pressure), and the check valve (which keeps water from flowing backward). Understanding how these pieces work together helps you recognize when something is wrong and why your water pressure might drop or your pump might run too often.

Key Takeaways

  • A well pump creates suction to pull water up from the well, then pressurizes it to send it through your home's pipes.
  • The pressure tank stores water under pressure so the pump does not run every time you use a small amount of water.
  • A check valve sits between the pump and the well to prevent water from flowing backward when the pump stops.
  • Submersible pumps sit inside the well casing, while jet pumps sit above ground and use a pipe with a foot valve to reach the water.

How the Pump Creates Suction and Pressure

The pump itself is an electric motor connected to an impeller—a spinning wheel with curved blades. When the motor turns on, the impeller spins fast inside a sealed chamber. As the blades move, they push water outward and create a low-pressure zone in the center. This low pressure acts like a vacuum and pulls water up from the well through the intake pipe.

Once the water enters the pump chamber, the spinning impeller forces it into a smaller space, which compresses the water and raises its pressure. This pressurized water then flows out through the discharge pipe toward your house. The faster the impeller spins, the higher the pressure it creates. Most household well pumps run at 1,200 to 3,600 revolutions per minute, which is fast enough to push water up several hundred feet and through your home's plumbing at usable pressure.

The Pressure Tank and How It Reduces Pump Cycling

A pressure tank is a large metal or composite container that stores water under pressure. When the pump sends pressurized water into the tank, the water compresses a rubber bladder or air pocket inside. This stored pressure allows water to flow to your taps even when the pump is off. The moment you turn on a faucet, water leaves the tank and pressure drops. When pressure falls below a set threshold—usually around 40 pounds per square inch—the pump switches back on automatically.

Without a pressure tank, the pump would start and stop dozens of times per day, even for small uses like filling a glass. This constant cycling wears out the motor and wastes electricity. The tank typically holds 20 to 80 gallons, depending on your household size and water use. A larger tank means the pump runs less often and lasts longer. Over time, the air pocket in the tank can shrink if it leaks or if water slowly dissolves the air, which is why pressure tanks need occasional maintenance.

The Check Valve Prevents Backflow

A check valve is a one-way gate installed between the pump and the well. It allows water to flow up and out toward your house, but it closes automatically if water tries to flow backward down into the well. Without this valve, when the pump stops, gravity would pull the water column back down the intake pipe and into the well. You would lose pressure when ready, and the pump would have to refill the entire pipe every time it started again.

The check valve is usually a straightforward spring-loaded flapper or ball that sits in the pipe. Water pressure pushes it open on the way up. When pressure drops or reverses, the spring snaps it shut. A worn or stuck check valve can cause low pressure, a pump that runs constantly, or a system that loses pressure overnight. If you notice water trickling back into the well or your pressure dropping when the pump is off, the check valve may need cleaning or replacement.

Submersible Pumps Versus Jet Pumps

There are two common types of well pumps, and they work differently. A submersible pump is a long, narrow cylinder that sits inside the well casing, submerged in water. The motor and impeller are sealed together at the bottom. Water surrounds the motor and cools it as it runs. Submersible pumps are quiet, efficient, and can pull water from very deep wells—some work at depths of 300 feet or more. The main drawback is that if it fails, you have to pull the entire pump out of the well, which requires a crane or winch.

A jet pump sits above ground, usually in a basement or pump house. It uses a small pipe with a foot valve at the bottom to reach down into the well. The pump creates suction through this pipe and pulls water up. Jet pumps are easier to service because they are above ground, but they can only pull water from depths of about 25 feet (shallow well jet pumps) or 50 feet (deep well jet pumps with a second pipe). They are also louder than submersible pumps. Most modern wells use submersible pumps because they are more reliable and work at greater depths.

How Pressure Switches Control When the Pump Runs

A pressure switch is an electrical device that turns the pump motor on and off based on tank pressure. It has two set points: a lower pressure (usually 40 psi) where it turns the pump on, and an upper pressure (usually 60 psi) where it turns the pump off. When you open a faucet, water leaves the tank and pressure drops. The moment it hits 40 psi, the switch closes an electrical contact and the pump starts. As the pump fills the tank, pressure rises. When it reaches 60 psi, the switch opens the contact and the pump stops.

The difference between the on and off pressures is called the pressure differential. A wider differential (like 40 to 60 psi) means the pump runs less often and the tank stores more water. A narrower differential causes more frequent cycling. If your pump is turning on and off constantly—sometimes every few minutes—the pressure switch may be stuck, the tank may be waterlogged, or the check valve may be leaking. A pressure gauge on the tank lets you see what is happening and helps a technician diagnose the problem.

Common Problems and What Causes Them

Low water pressure usually means the check valve is stuck or leaking, the pressure tank is waterlogged, or the pump intake is clogged with sediment. If pressure drops suddenly, the check valve has likely failed. If pressure drops slowly over hours or days, air may be leaking into the system or the tank bladder may be torn. A pump that runs constantly suggests the pressure switch is not shutting off, the tank is waterlogged, or there is a leak somewhere in the plumbing.

A pump that will not start at all may have a tripped circuit breaker, a blown fuse, or a failed pressure switch. If the pump starts but produces no water, the intake pipe may be clogged, the foot valve (on jet pumps) may be stuck, or the pump may have lost its prime—meaning the intake pipe is full of air instead of water. Most of these problems require a licensed well technician to diagnose and fix, but knowing how the system works helps you describe the symptoms accurately when you call for service.

Frequently Asked Questions

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

Warmer water is less dense than cold water, so the pump has to move more volume to maintain the same pressure in the tank. Additionally, most households use more water in summer for outdoor activities, gardens, and showers, which means the pump cycles more often to refill the tank.

Can a well pump run dry and damage itself?

Yes. If the well water level drops below the intake pipe, the pump will pull air instead of water. This is called losing prime. Running dry can overheat the pump motor and damage the impeller. Most submersible pumps have a thermal overload switch that shuts them off if they overheat, but repeated dry-running shortens the pump's life.

What does it mean when my pressure tank makes a hissing sound?

Hissing usually means air is leaking from the tank or the air valve is releasing pressure. This can happen if the bladder inside the tank has torn, allowing water to mix with the air pocket. A small amount of hissing during normal operation is normal, but constant hissing means the tank needs inspection or replacement.

How often should a well pump be serviced?

Most well pumps need a professional inspection every one to two years. A technician checks pressure settings, tests the check valve, inspects the pressure tank, and looks for signs of wear. Regular service catches small problems before they become expensive repairs and extends the pump's working life.

Why does my water smell like rotten eggs when the pump first starts?

This smell is usually hydrogen sulfide gas, which forms naturally in some groundwater. When the pump sits idle, gas collects in the intake pipe. The first water out smells bad, but the smell clears after a minute or two. If the smell persists, the well water itself may contain sulfur bacteria, which requires treatment beyond the pump system.