Well Pump Installer cheat sheet

A submersible pump's head-capacity curve is set by impeller diameter and stage count; more stages raise shutoff head and power draw at the same flow.

A check valve directly above the pump holds the discharge column; a leaking check valve causes backspin, pressure loss, and short cycling.

Bladder tanks separate air precharge from water; with the water side drained, precharge is measured and normally set about 2 psi below cut-in.

A pitless adapter transfers discharge below frost and seals the casing; its flow rating and O-ring size must match the drop pipe and casing.

Jet pumps use a venturi ejector; shallow single-pipe systems place the ejector near the pump, while deep two-pipe systems place it down the well.

A torque arrestor centers the pump and limits start-up twist; cable guards protect motor leads from abrasion against the casing.

The well seal supports the drop pipe and seals wiring and vent openings; an unsealed or damaged seal creates a path for surface contamination.

TDH = vertical lift + drawdown + pressure head + friction loss, all in feet; pressure head in feet equals psi times 2.31.

Water horsepower = gpm x TDH / 3960; brake horsepower = water horsepower / pump efficiency.

The pump operating point is where the pump curve crosses the system head curve; changes in pressure setting or pipe friction move that point.

A 40/60 psi switch corresponds to about 92.4 ft cut-in and 138.6 ft cut-out pressure head; 40 x 2.31 and 60 x 2.31.

Tank drawdown equals usable volume between cut-out and cut-in; minimum run time is drawdown volume divided by pump flow.

Pump intake must remain below maximum drawdown and above the well bottom; setting too high causes loss of water, too low causes sediment intake.

Friction loss rises with flow and pipe roughness; size discharge pipe for velocity generally below 5 ft/s to limit loss and erosion.

Pump capacity should not exceed tested well yield unless storage or controls limit pumping; excessive pumping can lower the water level below the intake.

Two-wire submersible motors contain start components internally and connect directly through the pressure switch; three-wire motors require a control box with capacitor and relay.

A pressure switch opens at cut-out and closes at cut-in; the cut-out setting must match tank precharge and system pressure requirements.

For single-phase 230 V motors, nameplate current and pump curve current should be checked at actual flow; high amps suggest overload, low voltage, or wrong rotation.

Voltage drop should be limited to about 3% on the branch circuit and 5% overall; undersized cable reduces starting torque and overheats the motor.

Insulation resistance measured with a megohmmeter detects moisture or cable damage; readings are compared with motor manufacturer values.

A failed start capacitor can cause humming and overload trips; capacitance is checked in microfarads and compared with the control box label.

All metal well casings, pump motors, and control boxes must be bonded and grounded; a ground fault can energize the water system.

Three-phase motor rotation is reversed by swapping any two power leads; single-phase rotation is fixed by internal wiring.

Pump setting depth is chosen from static water level, expected drawdown, well depth, and required motor cooling flow.

Before startup, the pressure tank precharge is set with the water side drained, typically 2 psi below cut-in for a 20 psi differential.

New or repaired wells are disinfected with a chlorine solution, then flushed until chlorine residual is acceptable before sampling.

Startup checks include supply voltage, running amps per leg, discharge pressure, flow rate, and drawdown; readings are recorded against design values.

Submersible cable splices must be waterproof and strain-relieved; heat-shrink or resin kits restore insulation and prevent ground faults.

A constant-rate flow test records pumping rate, water level, and time; the data estimate sustainable yield and allowable pump setting.

Pressure switch settings are adjusted only after confirming tank precharge and gauge accuracy; cut-in and cut-out differential controls cycle volume.

Pump rotation for three-phase units is verified at startup; reverse rotation produces low flow, high amps, and possible motor damage.

Short cycling results from a waterlogged tank, leaking check valve, stuck pressure switch, or pump oversized for available tank drawdown.

Loss of prime on jet or suction pumps is caused by air leaks, low water level, clogged intake, or a failed foot valve.

Before service, isolate electrical supply at the disconnect, apply lockout/tagout, and verify absence of voltage at motor leads.

Well pits and vaults can be confined spaces; atmospheric testing, ventilation, an attendant, and rescue equipment are required before entry.

A sanitary well cap must exclude insects and surface water while providing venting; a damaged cap or unsealed casing is a contamination pathway.

Backflow prevention is required where a well system connects to potable supply or chemical injection; air gaps and testable assemblies protect the supply.

Motor overload trips can indicate high amps from low voltage, worn pump stages, sand binding, or incorrect motor selection; current is checked before reset.

Water samples for bacteria are collected after disinfection and flushing using sterile bottles and proper sampling technique.