Well Pump Glossary: Key Terms and Definitions
The well pump sector operates across a specialized vocabulary that governs equipment selection, installation compliance, and service qualification. This reference covers the core terminology used by licensed well pump contractors, hydrogeologists, plumbing inspectors, and property owners navigating residential and commercial groundwater systems in the United States. Precise command of these terms is essential for reading equipment specifications, interpreting state well codes, and evaluating contractor proposals. The Well Pump Listings directory applies this terminology throughout its provider classifications.
Definition and scope
Well pump terminology spans three overlapping domains: mechanical and hydraulic engineering, regulatory and permitting language, and field service categories. These terms appear in state well construction codes, manufacturer technical datasheets, Environmental Protection Agency (EPA) private well guidance, and National Sanitation Foundation (NSF International) certification standards.
Aquifer — A saturated underground formation of rock, sediment, or soil that yields usable quantities of groundwater. Aquifers are classified as unconfined (water table aquifers, recharged directly from surface infiltration) or confined (artesian aquifers, bounded above and below by impermeable layers). Aquifer depth and yield directly determine pump type selection.
Static water level — The depth to the water surface in a non-pumping well, measured from grade. Published by the U.S. Geological Survey (USGS National Groundwater Monitoring Network) as a baseline measurement.
Pumping water level (dynamic level) — The depth to water during active pumping. The difference between static and dynamic levels is called drawdown.
Drawdown — The vertical distance the water level drops in a well during pumping, measured in feet. High drawdown relative to aquifer yield signals pump oversizing or aquifer limitations.
Well yield — The sustained flow rate a well can deliver, expressed in gallons per minute (GPM). Yield testing protocols are governed by state well codes; most states require documentation of yield at the time of well completion.
Total Dynamic Head (TDH) — The total equivalent height against which a pump must work, combining static lift, drawdown, pipe friction losses, and pressure requirements. TDH, expressed in feet or PSI, is the primary variable used to size a pump motor.
How it works
Understanding pump operation requires fluency in both hydraulic and electrical terminology.
Submersible pump — A sealed motor-and-pump unit installed below the water surface inside the well casing. The motor is water-cooled and drives one or more impellers that push water upward through the drop pipe. Submersible pumps dominate residential well installations in the United States.
Jet pump — A surface-mounted pump using a venturi ejector assembly to create suction. Shallow-well jet pumps operate where static water levels are within 25 feet of grade; deep-well jet pumps use a separate ejector lowered into the well and function at depths up to approximately 80–100 feet.
Impeller — The rotating disc inside a centrifugal pump that imparts velocity to water. Multi-stage submersible pumps stack 5 to 20 or more impellers to achieve high TDH performance.
Pressure tank (hydropneumatic tank) — A storage vessel containing a pre-charged air bladder or diaphragm that maintains system pressure between pump cycles. Tank pre-charge pressure, set to 2 PSI below the pump cut-in pressure (typically 28 PSI for a 30/50 switch setting), prevents pump short-cycling.
Pressure switch — An electromechanical device that starts the pump at the cut-in pressure and stops it at the cut-out pressure. Standard residential settings are 30/50 PSI or 40/60 PSI (NSF/ANSI 61 sets material standards for components in contact with drinking water).
Control box — An external electrical enclosure, required for two-wire and three-wire submersible motor wiring configurations, containing starting capacitors and relays. Absent on single-phase two-wire motors, which incorporate starting components inside the motor housing.
Drop pipe — The water delivery pipe from the pump to the surface, typically Schedule 80 thermoplastic or stainless steel. Pipe diameter and length factor directly into friction loss calculations within TDH.
Common scenarios
The following situations represent the primary contexts in which well pump terminology is applied in the field:
- New well installation — A licensed well driller logs aquifer depth and yield; a pump contractor sizes the submersible pump using TDH and GPM calculations; a plumbing or well inspector verifies installation against the applicable state well construction code.
- Pump failure diagnosis — Technicians distinguish between no-water calls attributable to electrical failure (blown fuse, failed capacitor, tripped breaker), mechanical failure (worn impellers, seized motor), or well problems (aquifer depletion, sand intrusion).
- Pressure system service — Waterlogged pressure tanks — tanks that have lost bladder integrity and fill completely with water — cause short-cycling, identifiable by pump run times under 30 seconds per cycle.
- Water quality testing — EPA guidance recommends annual testing of private wells for coliform bacteria and nitrates; terminology such as well casing, grouting, and sanitary seal describes the physical barriers that protect water quality.
- Permit and inspection review — State well codes (administered by agencies such as the California Department of Water Resources or the Texas Commission on Environmental Quality) define construction standards, setback distances, and casing requirements in regulatory language that mirrors this glossary.
The directory purpose and scope page explains how provider categories within this resource align with these service scenarios.
Decision boundaries
The boundary between related terms is frequently misapplied in contractor proposals and permit applications.
| Term Pair | Distinction |
|---|---|
| Submersible vs. jet pump | Installation depth and application; submersibles are preferred above 100-foot depths and are standard for deeper aquifers |
| Static level vs. dynamic level | Static is measured at rest; dynamic is measured under pumping load — only dynamic level determines pump setting depth |
| Well yield vs. pump capacity | Yield is an aquifer property; pump capacity is a mechanical rating — pump capacity must not exceed well yield |
| TDH vs. static head | Static head is only the vertical lift component; TDH includes friction and pressure requirements and is always larger |
| Pressure tank vs. storage tank | Pressure tanks maintain hydraulic pressure via air charge; storage tanks are atmospheric-pressure vessels used for high-demand buffering |
Contractors and inspectors referencing state well construction codes will encounter these distinctions in documentation requirements. The how to use this resource page describes how professional categories within this directory map to licensing tiers and service scope.
References
- U.S. Environmental Protection Agency — Private Drinking Water Wells
- U.S. Geological Survey — National Groundwater Monitoring Network
- NSF International — NSF/ANSI 61: Drinking Water System Components
- California Department of Water Resources — Well Standards
- Texas Commission on Environmental Quality — Water Well Regulations
- National Ground Water Association — Well Owner Resources