- Annulus
- The ring-shaped space between the outside of the casing and the wall of the borehole. Sealing it correctly is what prevents surface water and shallow contamination from travelling down alongside the casing into the aquifer.
- Borehole
- The drilled hole itself, before casing and equipment are installed. Its diameter determines what casing and pump will fit and how much annular space is available for grout.
- Casing — also called Well casing
- The pipe lining the borehole. It holds the hole open, seals out shallow contaminated water, and houses the pump. Most Houston-area residential wells use Schedule 40 PVC. Casing diameter also determines permit exemption status under the subsidence districts. Well drilling
- Drop Pipe
- The pipe running from the submersible pump up to the wellhead, carrying both the water and the weight of the pump. Its material and rating have to match the setting depth.
- Float Shoe
- A one-way valve fitted at the bottom of the casing string. It lets the casing be floated into place and allows cement to be pumped down and up the annulus without flowing back in.
- Grout / Pressure Cement — also called Pressure cementing
- Cement or bentonite pumped into the annulus to seal it. Pressure cementing forces the seal upward from depth, which produces a more reliable barrier than pouring from the surface. This is the single most important step for protecting a well from contamination.
- Liner
- A secondary length of casing set inside an existing well, usually to seal off a damaged or corroded section without abandoning the entire well.
- Multi-Zone Completion
- A well screened across more than one water-bearing zone so it draws from several formations at once. Used where no single zone yields enough on its own.
- Pitless Adapter
- A fitting that carries the water line out through the side of the casing below the frost line, so the connection stays buried and protected instead of sitting in an above-ground or pit enclosure.
- Plugging & Abandonment
- Permanently sealing a well that is no longer in use. Texas requires it — an open abandoned well is both a physical hazard and a direct pathway for surface contamination into the aquifer.
- Production Sand
- Graded sand placed in the annulus around the screen. It filters formation material before it reaches the screen and stabilises the zone. If it shifts or settles over time, a well can begin producing sand or lose yield.
- Rotary Drilling — also called Mud rotary
- The standard method for water wells in this region: a rotating bit cuts the hole while drilling fluid carries cuttings to the surface and holds the borehole open. Fast and well suited to the sand and clay sequences beneath the Houston area. Well drilling
- Sanitary Cap — also called Well cap
- A sealed, vermin-proof cover on top of the casing with a screened vent. It keeps insects, rodents, and surface water out while still allowing the well to breathe as the water level moves.
- Torque Arrestor
- A rubber-and-metal collar fitted above the pump to absorb the twisting force at start-up and keep the pump centred so it does not bang against the casing.
- Well Development
- The step after drilling and before the pump goes in — surging, airlifting, or pumping the well hard to pull fine material out of the formation. A properly developed well produces clearer water and more yield for its whole life. Skipping it is a common shortcut.
- Well Screen — also called Screen
- The slotted or perforated section of casing set across the water-bearing zone. It lets water in while holding back formation sand. Slot size is matched to the formation — too large and the well produces sand, too small and it clogs.
- Wellhead — also called Well head
- Everything at the surface where the well terminates — the top of the casing, cap, discharge piping, and electrical connections. Its condition is the first thing worth inspecting when a well develops problems.