Water Well Construction Method: Step-by-Step Guide for Reliable Groundwater Supply

When a project depends on a dependable groundwater source, the water well must be engineered and executed with tight QA/QC. Below is a clear, end-to-end sequence we use on live jobs—covering mobilisation, drilling, casing and screening, gravel packing, wellhead build-up, flushing and pump testing, and final commissioning. This mirrors the practical field method in our reference document and adds our site-proven notes for London/UK delivery.

1) Mobilisation & Site Readiness

• Locate & approve the well position with the Engineer; secure statutory/authority sign-offs.
• Clear access and services: temporary power and water, safe access route, flooding precautions, and a safe discharge route for well flushing.
• Move plant to site: drilling rig, auxiliary equipment, lifting gear; fix the rig over the marked well centre.

2) Drilling & Verticality Control

• Drilling method: down-the-hole hammer percussion to the design depth.
• Verticality tolerance: keep bore alignment within ~70 mm per 50 m; check alignment during works.
• Borehole protection: maintain diameter using an 18″ steel protection pipe during drilling.
• Sampling & logging: take two soil samples (≈0.5 kg) every 1.0 m; label with depth/date; test for moisture, permeability, and grading. Regular inspections with the Engineer throughout. 

3) Casing, Screens & Centralisation

• Casing: lower Ø300 mm UPVC casing with end cap; number and record pipe lengths.
• Screens: use screened sections through water-bearing strata; solid sections in dry layers and at least 1.5 m abovethe end cap.
• Centralisers: install at 5 m intervals to keep the string concentric. Engineer approval before lowering.

4) Gravel Pack (Filter Pack)

• Material: graded quartz gravel 1.5–2.0 mm between the steel protection pipe and UPVC casing/screen.
• Extent: place to 9.0 m above water level.
• Withdraw protection pipe until its lower end is at water level; trim excess and set the pipe 650 mm above a 100 mm blinding concrete layer. Fasten UPVC with a clamp. 

5) Wellhead Fabrication

• Steel plate collar welded around the protection pipe to approved details.
• DN600 wellhead cover ring welded to the protection pipe; the DN600 cover plate will later be bolted to this ring.
• Cast a 2.0 m × 2.0 m × 0.35 m raft around the well mouth for a robust, maintainable headworks.

6) Flushing, Pumping Test & Acceptance

• Install vertical test pump and DN150 riser; discharge lines routed safely away.
• Measure static water level, then conduct controlled pumping to specified discharge (fluctuation ≤ ±10 %).
• Record dynamic water level with an electric probe; confirm aquifer performance and decide final screen length.
• Remove test gear after Engineer’s acceptance. 

7) Final Fit-Out & Commissioning

• Install submersible pump with suction screen >3.0 m below dynamic level.
• Bolt DN600 cover plate, fit discharge elbow, air-release valve, and DN150 line to treatment (e.g., hydro-cyclone).
• QA/QC: follow the approved method statement and authority procedures for inspection, testing, and commissioning. Skilled personnel only. 

Why This Sequence Works

• Clean inflow & stable yield: matched screen zones + correctly graded gravel pack reduce fines migration.
• Maintainability: elevated headworks and reinforced wellhead protect against surface water ingress and damage.
• Traceable QA/QC: depth-indexed sampling, verticality checks, and witnessed pump tests prove performance and extend asset life.