NGWA CPI cheat sheet

Total dynamic head (TDH) is the sum of static lift, drawdown, discharge pressure head, and friction losses in the drop pipe, fittings, and discharge line; pump selection must satisfy TDH at design flow, not just rated capacity.

Pump capacity must fall within the well's safe yield; if the pump exceeds recharge, the well pumps dry, the motor loses cooling flow, and cycling accelerates wear on the pump, motor, and controls.

Submersible pump setting depth must keep the motor above the well bottom and below the drawdown water level; the motor needs passing water velocity of roughly 0.5 ft/s (0.15 m/s) to shed heat.

Friction loss rises roughly with the square of flow; doubling flow through the same pipe multiplies head loss by about four, so undersized drop pipe can dominate TDH at high flow.

Check valves hold the water column on shutdown and prevent backspin; a second check valve is installed on deep settings to reduce water hammer, but too many check valves trap pressure and complicate troubleshooting.

A pressure tank's drawdown equals the volume between cut-in and cut-out pressures; a 20/40 psi setting yields far less usable drawdown than 30/50 or 40/60 for the same tank size.

A 40/60 psi switch setting provides roughly 10 psi more usable pressure at fixtures than 30/50 but increases pump head and energy use; the tank precharge is set 2 psi below cut-in with the system drained.

Pump efficiency is best near the pump's design point; operating far to the left of the curve wastes energy and can cause upthrust, while operating far right risks downthrust and motor overload.

Static water level is the undisturbed water level before pumping; pumping water level is the stabilized level while pumping, and drawdown is the difference between them.

Specific capacity is pumping rate divided by drawdown (gpm per foot of drawdown); declining specific capacity over time signals well fouling, screen plugging, or declining aquifer yield.

Well yield is tested by pumping at a controlled rate and measuring drawdown and recovery; recovery to static level is typically recorded for at least as long as the pumping period.

A well casing and annular seal protect the aquifer from surface contamination; the grout seal extends from the surface to a depth set by the local well code, often at least 20 ft where the code requires it.

Well screen slot size is matched to the formation; a gravel pack is used where the formation is fine and uniform, while naturally developed wells rely on formation material to settle around the screen.

Artesian (confined) aquifers are bounded by low-permeability layers and can produce a potentiometric surface above the aquifer top; a flowing well occurs where that surface is above land.

Water quality testing for bacteria, nitrate, arsenic, and other parameters is specified by state or local rules; private wells are often not covered by federal drinking water standards, so local codes govern sampling.

Ohm's law: voltage equals current times resistance (V = I × R); power in watts equals volts times amps times power factor for AC circuits.

Single-phase motors use a start capacitor and/or start winding switched out by a centrifugal switch or relay; a failed start capacitor causes the motor to hum and trip the overload.

Three-phase motors are reversed by swapping any two of the three supply conductors; single-phase motors are reversed by swapping the start winding leads per the motor nameplate diagram.

Motor overload protection is sized to the motor's nameplate full-load amps (FLA) and service factor; a heater or overload set above nameplate FLA fails to protect the winding.

A pressure switch opens and closes the pump circuit at set pressures; contacts pitted or welded closed cause the pump to run continuously, while a failed diaphragm causes short cycling or no start.

A control box for a three-wire submersible pump contains the starting capacitor and relay; a two-wire pump has the start components built into the motor and needs no control box.

Grounding and bonding: the equipment grounding conductor and well casing bond must be continuous; a missing ground creates shock hazard and can cause nuisance tripping of GFCI protection.

A pump cycling rapidly on and off indicates a waterlogged tank, failed pressure switch, or check valve leak; continuous running with no flow points to a check valve failure or low water level.

Well construction, pump installation, and water testing rules are set primarily by state and local codes, not by a single federal standard; a contractor must know the code for each jurisdiction worked in.

A written contract should state scope, price, payment schedule, exclusions, warranty terms, and change-order procedure; verbal agreements invite disputes and are hard to enforce.

Lien rights and notice requirements vary by state; a contractor who fails to serve the required preliminary notice may lose the right to file a mechanic's lien for unpaid work.

Before digging or drilling, call the 811 one-call service and wait the required notice period; hitting a buried utility can cause injury, fines, and liability for repair costs.

Confined-space entry into a pit or vault requires atmospheric testing, ventilation, a permit, and an attendant; a pump pit can accumulate gases and is not entered casually.

Electrical work on pump circuits must follow the applicable electrical code and local licensing rules; lockout/tagout of the disconnect is required before servicing a pump motor.

Jobsite safety basics: keep guards on rotating shafts, use proper lifting technique for pump and motor assemblies, and verify the circuit is de-energized with a tester before touching conductors.

Record keeping: retain well logs, pump test data, water quality results, and signed change orders; documentation supports warranty claims, code compliance, and dispute resolution.