Well Pumps
One number sorts this whole category, and it is not horsepower. It is about 25 feet, and it comes from physics rather than from any manufacturer.
The short version
- Shallow well, 25 ft or less: jet pump, above ground, pulls water up.
- Deep well: submersible, down in the water, pushes it up.
- Suction cannot beat the atmosphere. A bigger motor does not move the 25-foot line.
- The pressure tank stops short cycling, and short cycling is what kills pumps.
- Sizing needs your well's numbers. We do not have them and neither does any chart.
Why suction stops at about 25 feet
A suction pump does not pull water. It removes air from the pipe, and the weight of the atmosphere pushes water up into the space.
That matters because the atmosphere has a fixed amount of pressure to offer. Perfect equipment at sea level tops out around 33 or 34 feet, and real pumps with real friction and real leaks manage rather less. EPA describes jet pumps as the usual choice for shallow wells of 25 feet or less.
The consequence is the useful part. Buying a more powerful jet pump does not get water from a deeper well, because the limit is not in the pump. Deeper wells use a pump that sits in the water and pushes, which has no such ceiling. That is the whole reason submersibles exist.
The two pumps
| Jet pump | Submersible | |
|---|---|---|
| Where it sits | Above ground | Down in the well, under water |
| How it moves water | Suction, so atmosphere does the lifting | Pushes from below |
| Usual depth | 25 ft or less | Deep wells |
| Servicing | Reach it without lifting anything out | Pulling the pump is the job |
| Noise | You hear it run | Underwater and quiet |
The pressure tank, and the failure it prevents
The tank holds a reserve of water under pressure so a pump does not start every time somebody washes their hands. Take that reserve away and the pump switches on and off constantly, which is short cycling.
Motors do not wear out from running. They wear out from starting. EPA describes a related version of the same failure: a submersible set just below the water table can draw the level down faster than the well recovers, so it cycles on and off as the water rises and falls, and this often damages the pump.
Tank sizing and pressure switch settings come from the pump and tank manufacturers, and they have to match each other. We are not going to print a pair of numbers here, because the right pair depends on equipment we cannot see.
Why there is no pump sizing calculator here
We build calculators when the inputs are honest. This one is not. Sizing a well pump needs your well depth, your static water level, your household's real flow demand, the pressure you want at the furthest tap, and the performance curve of the specific model. Change any one and the answer changes.
A calculator that asked for two of those and produced a horsepower figure would look useful and be wrong often. The generator sizing calculator exists because the reader can read every input off a nameplate. Here they cannot, and that is the difference.
When the power goes out
An electric well pump means no power, no water. On a homestead with animals, that is a faster problem than most people expect.
Hand pumps
Some are designed to share a casing with an installed electric pump, so you keep both. Whether one fits yours depends on casing diameter, static water level and the specific model's published limits. Manufacturers state those. Do not assume a hand pump fits your well because it is sold as a backup, and check the depth rating against your static level rather than your well depth.
Solar pumps
A solar pump is a system, not a product. You are buying a pump, a controller, panels, and a decision about whether to store energy in batteries or water in a tank. The common design stores water instead of electricity: pump when the sun shines, draw from the tank when it does not.
Voltage, head and flow all have to agree across those parts, and the manufacturer's pump curve is what tells you whether they do. This is not a place for a general rule.
Generator
A well pump is a motor with a large starting surge, which is exactly the load our generator sizing guide is built around. Take the running and starting watts off the pump nameplate rather than guessing.
Where this page stops
Equipment and how it works. Not installation, and not wiring. A well pump is a permanently wired motor in a wet environment, and that is an electrician and a well contractor, not an article.
Water quality is a different subject with its own page. If you want to know what is in your water, our well water testing guide covers home kits against certified labs.
Common questions
What is the difference between a jet pump and a submersible pump?
Where the pump sits, and that follows from physics. EPA describes jet pumps as the most common choice for shallow wells of 25 feet or less: they mount above ground and pull water up by suction. Submersible pumps are the most common choice for deep wells, and they sit down in the water pushing it up instead. Pulling has a limit. Pushing does not have the same one.
Why is 25 feet the limit for a shallow well pump?
Because suction does not really pull. Removing air above the water lets atmospheric pressure push it up the pipe, and atmosphere only has so much pressure to give. That caps the practical lift at around 25 feet regardless of how powerful the pump is. A bigger motor does not move the limit, which is why deep wells use a pump that sits in the water instead.
How do I know how deep my well is?
Your well log, if one exists. Many states keep well construction records, and the driller may have filed one. Depth is also not the same as static water level, which is where the water actually stands when the pump is off, and static level is what a pump has to work against. A well contractor can measure both.
What does a pressure tank do?
It holds a reserve of pressurised water so the pump does not have to start every time somebody opens a tap. Without enough reserve the pump switches on and off repeatedly, which is called short cycling. EPA notes a submersible set too close to the water table can draw the level down too fast and cycle on and off as it recovers, and that this often damages the pump.
What size well pump do I need?
We are not going to give you a number, and any page that does without knowing your well is guessing. Sizing needs well depth, static water level, the flow your household actually uses, the pressure you want at the tap, and the pump's own performance curve. Those come from a well log, a measurement and the manufacturer's curve for a specific model, not from a rule of thumb.
Can I use a hand pump as a backup on my existing well?
Sometimes, and it depends entirely on your well and the specific hand pump. Fit depends on casing diameter, static water level, and whether the pump is designed to share the casing with an installed electric pump. Manufacturers publish those limits. Do not assume a hand pump fits your well because it is sold as a backup.
The rest of the water system
Sources: EPA, learn about private water wells. Your well log, your well contractor and the manufacturer's pump curve outrank any general guidance for your own system.