Water well drilling: the process, step by step

Water well drilling turns a spot on your property into a working private water supply in a series of steps: planning and permits, choosing a contractor, drilling and casing the well, sealing and developing it, testing its yield, installing the pump, and testing the water. This guide walks through each step, what happens, and what to ask, so you can follow the work and check it. It is a homeowner's guide, not drilling instructions.

How is a water well drilled?

A drilled well is bored with a truck-mounted rig. The U.S. Geological Survey describes drilled wells as built with rotary or percussion (cable tool) equipment, and notes that local subsurface conditions determine how deep a well must go and where water stands in it. USGS: Groundwater Wells The National Ground Water Association lists rotary, cable tool, down-the-hole and reverse circulation drilling as common methods for household wells, and says drilling can take hours or days depending on depth and geology. NGWA Well Owner's Guide (2021) [USGS source note] [NGWA-GUIDE source note]

The rig advances the hole until it reaches a water-bearing zone that supplies enough water. Casing is set to hold the hole open, the space around the casing is sealed with grout, and a screen is added where loose material needs one. Well drilling methods compares the techniques.

The water well drilling process at a glance

Step 1: plan before anyone drills

Start with how much water you need and where the well can go. Household use is commonly estimated at 80 to 100 gallons per person per day. USGS: How much water do I use at home each day? Then find nearby well reports to see what depths and yields others found; see how to find water well logs and how deep a residential well should be. Choose a location that meets setback rules, sits uphill of contamination sources and gives the rig access; see where to drill a well on your property. [USGS-HOMEUSE source note]

Step 2: permits and local rules

Requirements vary widely: some states require notice to a state agency before drilling, others route permits through county health departments, and a few have no statewide construction standards. EPA: Private Drinking Water Well Programs in Your State Water well drilling licenses and permits explains how the pieces fit, and water well permits by state lists official sources. [EPA-STATES source note]

Step 3: choose water well drilling contractors and sign a clear contract

Get written, itemized quotes from more than one contractor and check each license with the issuing agency. NGWA's contract guidance lists what to itemize, including drilling and casing per foot, grouting, development, test pumping, disinfection, and drilling deeper or a second well. NGWA (Wellowner.org): Guidelines for Written Contracts Agree a maximum depth in writing and what happens if the hole is dry; see who pays for a dry hole. The vetting questions and quote checklist help you compare bidders, and the cost calculator adds up their numbers. [NGWA-CONTRACT source note]

Steps 4 and 5: drilling, casing and sealing

During drilling, the driller records the material at each depth and where water is found. Casing keeps the hole open and, with grout, keeps out dirt, surface water and lower-quality groundwater; some states set minimum casing lengths. EPA: Learn About Private Water Wells A pitless adapter lets the water line leave the casing below the frost line, and a vented, vermin-proof cap closes the top. See well casing and completion. [EPA-LEARN source note]

Step 6: how is a new well tested?

After drilling, the well is developed to clear fines, then tested. A proper yield test measures the static water level, the drawdown during pumping, and the recovery afterward; a short flow check is only a snapshot. Water Systems Council: wellcare Guide to Evaluating Water Wells (for home inspectors) The result decides whether the well meets your needs and how to size the pump. Well pump tests explains the report, and how many GPM a well should produce sets the target. [WSC-INSPECTOR source note]

Steps 7 and 8: pump, connection and water testing

A finished well is not yet a water system. The pump, pressure tank, water line and electrical work are often separate line items, sometimes by separate licensed installers; see planning a pump for a new well and complete well installation cost. Before anyone drinks the water, test it through a certified lab. Private wells are the owner's responsibility; EPA notes private domestic well water is not federally regulated the way public systems are. EPA: Private Wells The CDC recommends testing at least yearly for total coliform bacteria, nitrates, total dissolved solids and pH. CDC: Guidelines for Testing Well Water [EPA source note] [CDC-TEST source note]

Step 9: keep the records

Contractors must file well logs with their states when a new well is completed. NGWA Well Owner's Guide (2021) Keep your copy with the yield test, pump details and water tests. These records guide future maintenance and matter when you sell; see the well maintenance checklist. [NGWA-GUIDE source note]

What can go wrong, and how to prepare

• The hole is dry or weak. No driller can guarantee water; see what happens if a new well has no water.
• Depth runs past the estimate. A written maximum depth turns this into a decision instead of a surprise.
• Water quality needs treatment. Quality depends more on the aquifer than on depth, so budget for treatment until the lab results are in. Water Systems Council: Determining the Depth of a Well
• Schedules slip. Rig backlogs, permits and lab turnaround all add time; see how long it takes to drill a well.

When you're ready to look for contractors, start with the well driller directory and verify each one independently. An independent membership lookup is NGWA's contractor lookup, which does not endorse or guarantee listed companies. [NGWA source note]