Glossary

Agricultural wells — also called irrigation wells or farm wells — are designed to produce significantly higher GPM than residential wells to meet the water volume demands of farming operations. Common agricultural well applications include center pivot or drip irrigation systems for crops, stock watering for cattle, poultry, or other livestock, greenhouse operations, and aquaculture.…

Air rotary drilling is the primary method used by Trident Drilling for water well construction in Northern Idaho. The system uses a rotary drill bit driven by a top-mounted motor, with high-pressure compressed air injected down the drill string to both cool the bit and blow drill cuttings back up to the surface through the…

An aquifer is a subsurface geological formation that contains sufficient saturated permeable material to yield usable quantities of water to wells. Aquifers are divided into two main types: unconfined aquifers, where the water table is at the top of the saturated zone and is recharged directly by precipitation and surface water; and confined aquifers, which…

Aquifer recharge rate describes how quickly an aquifer regains water lost to pumping or seasonal drawdown through natural infiltration from the surface. For the Spokane Valley–Rathdrum Prairie Aquifer, recharge occurs primarily through precipitation on the Rathdrum Prairie, river and stream infiltration, and seasonal snowmelt from surrounding mountains. The SVRP Aquifer’s high permeability allows for relatively…

Basalt is an extrusive igneous rock formed from solidified lava flows. In Northern Idaho, basalt formations underlie parts of the region — particularly at higher elevations and in areas outside the Rathdrum Prairie’s sedimentary aquifer zone. When a drill bit encounters basalt, penetration rates slow significantly, drill bit wear increases, and water production depends entirely…

Commercial well drilling addresses the water supply needs of non-residential properties — including commercial buildings, multi-family housing developments, resorts, businesses, and industrial sites. Commercial wells are typically engineered for higher GPM output than residential wells to meet the volume demands of multiple users or commercial processes. The permitting process is more complex than residential permitting,…

Crack-water drilling — sometimes called fracture-zone drilling — refers to the practice of drilling through dense basalt or other volcanic rock to reach groundwater stored in natural fractures, joints, or void spaces within the rock mass. Unlike aquifer drilling in sedimentary zones, where water is held in the pore spaces between sand and gravel particles,…

Deep polling occurs when a driller continues drilling past a productive water zone — either claiming insufficient yield or simply drilling without disclosing that water has already been reached at a shallower depth — in order to charge for additional footage at the per-foot billing rate. In regions like Northern Idaho where customers are rarely…

Drawdown measures how much the water level inside a well drops when a pump is operating. As the pump extracts water, the level inside the well casing falls until an equilibrium is reached between the pumping rate and the rate at which water flows from the surrounding formation into the well. A well with a…

A flow rate test (also called a GPM test or well yield test) is a pump test conducted on an existing or newly drilled well to measure its water production rate over a defined period. For real estate and construction loan purposes, the test produces a documented GPM figure that lenders use to verify the…

Gallons per minute (GPM) is the standard metric used in the well drilling industry to measure a well’s flow rate — the volume of water the well produces per unit of time under pumping conditions. A residential well in Idaho typically needs to produce a minimum of 1 to 3 GPM to support basic household…

The grout seal — also called an annular seal — fills the gap between the outside of the well casing and the borehole wall from the surface down to the depth required by IDWR regulation. In Idaho, grouting is required to a minimum depth to ensure that surface runoff, agricultural chemicals, and bacteria cannot travel…

Hard rock drilling refers to the process of penetrating consolidated, crystalline, or volcanic rock formations to reach water-bearing fractures or zones within the rock mass. In Northern Idaho, basalt formations are common in elevated areas and parts of the region away from the Spokane Valley–Rathdrum Prairie Aquifer basin. Hard rock wells use air rotary drilling…

The Idaho Department of Water Resources (IDWR) is the primary regulatory body governing groundwater use in Idaho. Its responsibilities include issuing well drilling permits before any drilling can begin, establishing and enforcing well construction standards (including casing depth, grout seal requirements, and setback distances), receiving and maintaining the public well log database, administering Idaho’s water…

An injection well is a drilled structure designed to direct fluids into a subsurface formation rather than extracting water from it. Unlike extraction wells, injection wells return fluids to the ground. Applications in Northern Idaho include stormwater management systems that direct surface runoff into the subsurface for infiltration, land remediation projects that reintroduce treated water…

In Idaho, well drilling is a licensed profession regulated by IDWR. A licensed well driller has met the state’s education, examination, experience, and insurance requirements to legally perform well construction work. Licensing is specific to the work type — there are separate licensing categories for drillers, pump installers, and monitoring well contractors. Only licensed drillers…

A monitoring well is a purpose-built well designed to allow access to groundwater at a specific depth for sampling and level measurement. Unlike water supply wells, monitoring wells are not intended to produce large quantities of water. They are installed to track groundwater quality and levels near industrial sites, fuel storage areas, mining operations, contaminated…

Mud rotary drilling circulates a fluid mixture (drilling mud, typically bentonite clay and water) down through the drill string and back up the annular space to remove drill cuttings and maintain borehole wall stability through hydrostatic pressure. The fluid cake that forms on the borehole wall prevents collapse in loose, unconsolidated formations such as sand,…

A new construction well is drilled during the development phase of a property before or during building construction. Timing is critical: the well must be drilled and permitted, and a GPM test must be completed and documented before construction loan approval or building permit issuance in many Idaho jurisdictions. The well is typically drilled in…

A pressure tank (also called a captive air tank or bladder tank) is installed between the submersible pump and the household plumbing system. Inside the tank, a rubber bladder separates a pre-charged air chamber from the water storage chamber. As the pump runs, water fills the tank, compressing the air bladder. When a faucet opens,…

A pump system is the above-well and in-well assembly that draws water from the aquifer to the surface and maintains the household or commercial water supply. A standard residential pump system includes: a submersible pump (installed inside the well casing at depth), drop pipe (connecting the pump to the surface), electrical wiring and controls, a…

Residential well drilling is the process of creating a new private water well for a single-family home, duplex, or small residential property in an area without municipal water access. The full process includes a site evaluation to assess geology and setback compliance, IDWR permit application, mobilization of the drill rig, drilling to the required depth,…

A sanitary well cap is the protective cover that seals the top of the well casing at the surface. It is specifically designed to keep out insects, small rodents, surface water, and foreign debris while allowing for pressure equalization between the well interior and the atmosphere through a fine-mesh screened vent. A properly functioning well…

Setback requirements are regulatory minimums specifying how far a well must be located from sources of potential contamination. In Idaho, IDWR establishes minimum setback distances for various contamination sources. Common setback rules include minimum distances from septic tanks and drain fields (typically 50 to 100 feet), underground fuel storage tanks, animal feedlots or enclosures, irrigation…

A site evaluation (also called a site survey or site assessment) is Trident Drilling’s standard pre-drilling process. It involves a physical visit to the property to assess: probable subsurface geology and aquifer type based on location and available data; setback compliance — the distances from the proposed drill location to septic systems, fuel tanks, animal…

The Spokane Valley–Rathdrum Prairie (SVRP) Aquifer is a glacial outwash aquifer composed of highly permeable sand, gravel, and cobble deposits formed by ancient glacial meltwater floods. It underlies a significant portion of the Rathdrum Prairie in Kootenai and Bonner Counties in Northern Idaho and extends west beneath the Spokane Valley in Washington. The aquifer is…

Static water level (SWL) is the depth from the surface to the top of the water column in a well under non-pumping (static) conditions. It is measured after the well has rested long enough for the water level to stabilize — typically several hours after any pumping has stopped. The static water level is recorded…

Water rights in Idaho are governed by the doctrine of prior appropriation — ‘first in time, first in right.’ This means that earlier water right holders have priority over later ones during times of water scarcity. In Idaho, domestic groundwater use (household water from a private well) falls under an exempt category that does not…

Water testing involves collecting a sample from a well and submitting it to a certified laboratory for analysis. A standard basic test for residential wells includes coliform bacteria, E. coli, nitrates, and pH. A comprehensive test adds hardness, iron, manganese, arsenic, lead, turbidity, and other site-relevant parameters. In Idaho, water testing documentation is required by…

A water tote trailer carries a large portable water storage tank on a wheeled trailer that can be delivered to a property and connected to an exterior fill point or temporary holding tank. Trident Drilling uses water tote trailers as part of its emergency water delivery service to provide potable water to households and properties…

A water well is a structure — typically a cased borehole — that accesses an underground aquifer and allows groundwater to be pumped to the surface for drinking, sanitation, irrigation, or commercial use. In Northern Idaho, private water wells are the standard water supply for rural and semi-rural properties that are not served by a…

Well abandonment — also called well decommissioning or well sealing — is required by Idaho law when a water well is permanently removed from service. The process involves removing the pump and all equipment, filling the borehole with approved sealing materials (typically bentonite and cement grout) from the bottom to the surface, and filing an…

Well adequacy is an assessment — often performed as part of a well inspection — that determines whether a well’s yield (GPM), water quality (potability), and system condition collectively meet the requirements for the property’s intended use. For a residential property, adequacy typically means the well produces at least the lender’s minimum GPM threshold, water…

Well deepening involves re-entering an existing well casing and continuing the borehole to a greater depth than the original construction. It is typically considered when an existing well’s water production has declined — often due to a dropping water table during drought or long-term aquifer changes — or when the current well is producing insufficient…

A well inspection is a comprehensive assessment of an existing water well and its components conducted by a licensed professional. The inspection evaluates: the wellhead’s physical condition (casing height, cap integrity, surface drainage); the well log documentation and construction history; current static water level compared to the well’s original recorded level; a pump test to…

A well log — sometimes called a driller’s report or well completion report — is the legal and technical record of a well’s construction. In Idaho, licensed drillers are required by law to file a well log with IDWR after completing any new well. The log documents the well’s location (legal description), total depth, casing…

Well rehabilitation encompasses a range of treatments and repairs used to recover or improve a well’s performance. Common rehabilitation techniques include mechanical cleaning to remove mineral encrustation or bacterial growth from the casing and screen, chemical treatment with acid or chlorine to dissolve mineral deposits or disinfect bacterial biofilm, redevelopment to improve the flow of…

Well yield is the long-term productive capacity of a well expressed in gallons per minute (GPM). It is distinct from instantaneous flow rate because yield accounts for the well’s ability to sustain production over time without excessive drawdown. A well might briefly produce 10 GPM but sustain only 5 GPM over a four-hour pump test…

Worst-case scenario bidding is the estimating methodology Trident Drilling uses for all well drilling projects. Rather than providing a low attractive estimate based on the best-case (shallow) well depth and then billing significantly more when depth exceeds expectations, Trident provides an estimate range that includes what the project would cost if the well must be…