Deep Well Pump (Submersible) Guide

If your water comes out of the ground more than about 25 feet down, a jet pump won’t cut it and you need a submersible deep well pump sitting at the bottom of the casing. That single component pushes every gallon into your house, so when it fails you have no water, no toilet, and no shower until it’s fixed. This guide walks you through sizing, pricing, and the actual pull-the-pump job so you know what you’re dealing with before you call anyone.

How a Submersible Well Pump Works

A submersible pump is a long, skinny cylinder — usually 3 to 4 inches in diameter and 2 to 3 feet long — that hangs on the drop pipe deep inside a 6-inch well casing. The motor sits at the bottom, the multi-stage impeller stack sits above it, and the whole unit is fully underwater. Because water is a far better heat sink than air, submersibles run cooler and last longer than the old above-ground jet pumps. Most last 8 to 15 years, sometimes 25 in a clean well with steady voltage.

Power runs down a waterproof cable strapped to the drop pipe. When your pressure switch senses the tank has dropped to its cut-in point (commonly 40 PSI), it closes, the motor spins, and water is shoved up the pipe into the pressure tank. When the tank hits the cut-out (60 PSI), the switch opens and the pump stops. You want the pump to run in reasonable cycles, not kick on for two seconds every time someone washes their hands.

Sizing: HP, GPM, and Depth

Three numbers decide which pump you buy: how deep the pump sits, how many gallons per minute you need, and the horsepower required to move that water against gravity plus friction.

• Depth: Residential deep wells commonly run 100 to 400+ feet. The pump does not sit at the very bottom — it hangs 10 to 20 feet off the bottom so it never sucks sediment. The vertical distance from the pumping water level up to your pressure tank is the “total head” you’re fighting.
• GPM: A typical three-bed, two-bath house wants 8 to 12 GPM at the fixtures. Add up simultaneous demand — a shower (2.5 GPM), a running toilet fill (3 GPM), and a dishwasher — and you land around 8 to 10 GPM for most homes.
• Horsepower: Deeper wells and higher flow need more HP. As a rough guide: 1/2 HP handles up to roughly 100–150 ft, 3/4 HP suits 150–250 ft, 1 HP covers 250–350 ft, and 1.5 HP handles the deep 350–450 ft wells or homes wanting extra flow. Don’t just buy the biggest motor — an oversized pump short-cycles and burns out the switch.

Every pump ships with a performance curve. Find your total feet of head on the chart, read across, and confirm it still delivers your target GPM at that depth. If a 1/2 HP pump gives 10 GPM at 100 ft but only 4 GPM at 300 ft, that pump is wrong for a 300-ft well.

The Pressure Tank Matters as Much as the Pump

The pump fills a pressure tank, and the tank is what actually feeds your house between pump cycles. A properly sized tank keeps the motor from starting and stopping constantly — every start is wear. For a 1/2 to 1 HP pump, a 32-gallon or 44-gallon bladder tank is common; the goal is at least one minute of run time per cycle.

Set the tank’s air pre-charge 2 PSI below your pump’s cut-in pressure. If your switch cuts in at 40, charge the empty tank to 38 PSI with a bicycle pump and a tire gauge. Get this wrong and you’ll waterlog the tank, short-cycle the pump, and shorten its life by years. A waterlogged tank that feels heavy and gives you machine-gun pump cycling is one of the most common “my pump is dying” calls that turns out to be a $200 tank, not a pump.

What a Deep Well Pump Costs

The pump itself is the cheap part. Here’s a realistic breakdown:

• Pump unit: $250–$400 for a 1/2 HP, $400–$700 for a 1 HP, $700–$1,200 for 1.5 HP name brands like Goulds, Franklin, or Grundfos.
• Drop pipe and wire: New poly or galvanized drop pipe plus submersible cable runs $150–$500 depending on depth.
• Pressure tank: $200–$450 for a quality bladder tank.
• Switch, fittings, torque arrestor, safety rope: $75–$150.
• Professional labor: $500–$1,500, driven mostly by depth and whether they need a truck-mounted hoist.

All-in, a professional deep well pump replacement typically lands between $1,500 and $4,000, with deep 400-ft wells and 1.5 HP units at the top of that range. A DIY job on a 150-ft well can come in under $800 in parts.

Install and Replacement Timeline

A crew with a well hoist truck can pull an old pump and set a new one in 3 to 5 hours on a shallow-to-mid well. Go DIY on a 300-plus-foot well and plan a full day — the drop pipe full of water is heavy, and hand-pulling 400 feet of pipe is genuinely hard physical work. Budget for two strong people minimum.

How to Pull the Pump Yourself

Pulling a deep well pump is doable on wells under about 200 feet with two people. Deeper than that, rent a hoist or hire it out — you can drop the whole assembly down the casing and turn a $600 job into a well-drilling nightmare.

1. Kill the power. Shut off the breaker to the pump and verify it’s dead. This is 240V in water — non-negotiable.
2. Remove the well cap. Loosen the bolts on the sanitary well cap and lift it, feeding the wire and pipe through as you go.
3. Pull steadily, hand over hand. As pipe comes up, have your helper support each section. If it’s galvanized pipe in threaded sections, you’ll unthread each 21-ft length as it clears; poly pipe comes up in one continuous run.
4. Never lose the safety rope. Keep tension on the nylon safety rope tied to the pump — if the pipe slips, the rope is your backstop.
5. Inspect at the surface. When the pump breaks the surface, check the impeller for sand, the cable for cracked insulation, and the check valve for gunk.
6. Set the new pump. Wire it, attach a torque arrestor to protect the casing from motor kick, tie on a fresh safety rope, and lower it back to the same depth the old one hung at.

Signs Your Pump Is Failing

Watch for these before you’re standing in a dry shower:

• Air spitting and sputtering at the faucets — the pump may be losing prime or the water table dropped below it.
• Pressure that climbs slowly or never reaches cut-out — worn impellers.
• Rapid on-off cycling — usually the tank or check valve, not the pump.
• Tripping breakers — a failing motor pulling too much amperage.
• Sandy or cloudy water — the pump has dropped too close to the bottom or the well is silting in.

Test the amp draw against the motor’s nameplate before condemning it. A deep well pump that pulls normal amps but won’t build pressure is a mechanical failure; one that trips instantly is electrical. Knowing which saves you from buying the wrong part.

Wire, Voltage, and Motor Protection

A surprising number of premature pump deaths trace back to wiring, not the pump. Voltage drop over a long cable run starves the motor, makes it run hot, and shortens its life. On a 300-ft run, undersized wire can cost you 10 percent of your voltage before it ever reaches the motor. Size the submersible cable up a gauge from what the chart’s bare minimum suggests — going from 12 AWG to 10 AWG on a deep run is cheap insurance against a $1,000 motor.

Three-wire motors use a separate control box mounted near the pressure tank that holds the start capacitor; two-wire motors put everything downhole. Two-wire is simpler to wire but means pulling the pump to replace a failed start component. Three-wire lets you swap a $40 capacitor at the surface instead of pulling 300 feet of pipe — worth considering when you replace. Either way, install a properly sized pump-saver or low-water cutoff relay; it kills the motor if the well runs dry, preventing the classic burnout when the water table drops in a drought.

Bottom Line

Size for depth and GPM off the pump curve, match the pressure tank and pre-charge to your switch, protect the motor with correct wire and a dry-run cutoff, and respect the physical reality of pulling hundreds of feet of water-filled pipe. Get those right and a good submersible will quietly deliver water for a decade or more without you ever thinking about it.