How a Water Well Drilling Rig Works

A water well drilling rig is a specialized industrial machine designed to:

✔ Break through earth layers

✔ Remove cuttings

✔ Stabilize the borehole

✔ Reach the aquifer

✔ Install casing and screens

✔ Build a functional water well

Most rigs used in Arizona are rotary drilling rigs with the power to drill hundreds—and often thousands—of feet deep.

Modern rigs cost anywhere from $300,000 to $1 million+, depending on size, torque, and capabilities. They are engineered to handle Arizona’s harsh geology, from clay soils to volcanic basalt.

A professional-grade drilling rig includes several essential systems. Here’s a breakdown of the most critical components:

1. Mast / Derrick

A tall steel tower that supports the drill pipe as it is raised and lowered. Some rigs can lift thousands of pounds of drill string at a time.

2. Drill String (Drill Pipe Sections)

Steel pipes that connect together to reach deep underground. As the well goes deeper, more pipe is added.

3. Drill Bit

• The tool that actually cuts through earth layers. Types include:
• Tri-cone bits – for rock and mixed formations
• PDC bits (polycrystalline diamond) – for hard rock
• Drag bits – for softer formations
  

4. Rotating Head

This system spins the drill string, allowing the bit to cut through rock.

5. Mud Pump / Air Compressor

Used to circulate drilling fluid or compressed air down the borehole to:

• Cool the drill bit
• Bring cuttings to the surface
• Stabilize the wellbore

Air rotary rigs are most common in Arizona because air easily lifts rock fragments and sand in dry formations.

6. Blowout Preventer (BOP)

A safety device that prevents uncontrolled pressure releases.

7. Casing, Screen, and Gravel Pack

Installed once the target aquifer is reached. These components keep the well stable and ensure clean water flow.

The drilling process is more complex than simply digging downward. Here’s what really happens:

Step 1: Positioning the Rig & Preparing the Site

Before drilling starts, the crew:

• Levels the ground
• Stabilizes the rig
• Aligns it with the chosen drill point
• Prepares water, air, and power systems

Arizona Well Drilling LLC uses geophysical testing first to select the most productive location.

Step 2: Drilling Through the Unsaturated Zone

The first layer the bit goes through is the unsaturated zone, also called the vadose zone.

This is the part of the ground where soil and rock contain some moisture, but the pores are not fully filled with water.

Most Common Layers in Arizona’s Unsaturated Zone

Depending on the region, we typically drill through:

• Sandy soils
• Caliche (cement-like desert hardpan)
• Clay beds
• Alluvial deposits
• Gravel layers
• Volcanic ash or basalt (common in northern AZ)

Cuttings are brought up to the surface by either air or drilling mud.

Step 3: Reaching the Water Table

Homeowners often ask:

“What happens when you drill through the unsaturated zone?”

Answer: You reach the saturated zone, which begins at the water table—the top of the aquifer.

This is where all pores and fractures are fully filled with groundwater.

In Arizona, water table depth can vary from:

• 150–400 feet in areas like St. Johns
• 500–1,200+ feet in Phoenix basins
• 300–800 feet in Tucson regions
  

Step 4: Drilling Into the Aquifer

Once the rig reaches the aquifer, drilling continues deeper into the water-bearing formation to build a stable, high-yield well.

Common aquifers in Arizona include:

• Alluvial aquifers (sand, gravel)
• Basin-fill aquifers (major population centers)
• Fractured bedrock aquifers (north and eastern AZ)

The drilling rig continues rotating and circulating air/mud to remove cuttings.

Step 5: Installing the Well Casing

After the final depth is reached, steel or PVC casing is lowered into the borehole.

Casing protects your well by:

• Preventing collapse
• Blocking contaminants
• Supporting long-term water flow

We then set well screens in the aquifer zone to allow clean water in while filtering sediment.

Step 6: Gravel Packing & Annular Seal

A specially sized gravel is placed around the screened section to filter water.

Above that, we create a bentonite seal to prevent surface contamination from entering the well.

Step 7: Deep Cleaning & Air Development

Using high-pressure air, we flush the well to:

• Remove fine particles
• Improve flow rate
• Increase water clarity
• Develop the well to its maximum yield

This process can dramatically increase gallons-per-minute output.

Step 8: Installing the Water Well Pump

Once development is complete, we install the pump system—typically a submersible pump placed deep in the aquifer.

Pump size depends on:

• Depth
• Water level
• Household or irrigation needs
• Desired flow rate (GPM)
  

Step 9: Water Testing & Final Inspection

Before finishing the job, professional drillers perform:Pump size depends on:

• Flow rate testing
• Pressure testing
• Water quality testing
• Safety inspections

This ensures your water is clean, reliable, and safe.

Arizona geology requires more than a basic drilling setup. Most professional drillers use one of these rig types:

Air Rotary Rigs (Most Common in Arizona)

Uses compressed air to lift cuttings. Ideal for:

• Hard rock
• Desert soils
• Deep aquifers
• Fast drilling
  

Mud Rotary Rigs

Uses drilling fluids to stabilize loose soils. Ideal for:

• Alluvial aquifers
• Sandy or unstable formations
  

Dual Rotary Rigs

Excellent for challenging geology and deep wells.

Arizona Well Drilling LLC uses rigs matched specifically to each region’s subsurface structure.

Arizona has some of the deepest groundwater wells in the country. Typical depths:

The drilling rig must be powerful enough to handle these depths safely.

Arizona has an extremely mixed geological profile, meaning the rig may encounter:

Each layer requires different:

Experienced drillers adjust constantly throughout the process.

Water well drilling rigs include multiple safety features:

A properly trained crew keeps all systems within safe operating conditions at all times.

You may have seen “DIY water well drilling rigs” online—but these setups cannot reach Arizona aquifers.

Why DIY rigs fail in Arizona:

DIY systems work only in wet, shallow regions with soft soil—not in Arizona.

The success of your well depends on the rig and the crew operating it.

At Arizona Well Drilling LLC, our rigs and crew deliver:

Experience + proper equipment = a better well.

Even the best drilling rig cannot guarantee a productive well without:

That’s why choosing an experienced team matters more than the machine itself. If you want a high yield well, call our experts at Arizona Well Drilling to learn more.