Water Well Rehabilitation

What is water well rehabilitation?

Almost every water well produces less over time. The water is usually still in the aquifer — what changes is the well's ability to let it in. Rehabilitation is the work of recovering that lost intake capacity: bringing a well's yield and specific capacity back toward its original design performance.

It sits between two more drastic options. Doing nothing lets the decline continue until the well is abandoned; drilling a replacement is expensive and disruptive. Rehabilitation recovers an existing asset — often at a fraction of the cost of a new well — provided the treatment can actually reach where the well is plugged.

When a well needs rehabilitation

The signals that a well is plugging rather than simply being over-pumped include:

• Falling specific capacity — the well needs more drawdown to deliver the same flow.
• Longer pump run times and rising energy cost per unit of water delivered.
• Sand or turbidity appearing in the discharge.
• Water-quality changes — iron staining, odour, or slime that point to biofouling.

A stronger pump can mask the problem for a while by raising flow, but it does not stop the well from degrading. The article Why water wells lose yield covers the underlying causes — mineral incrustation, iron and manganese, biofouling, and gravel-pack plugging — and where each one occurs.

How to diagnose the problem

Choosing a rehabilitation method starts with understanding where and why a well is plugging. Four sources of evidence matter:

• Specific capacity and a step-drawdown test — the honest measure of a well's health: flow per unit of drawdown (m³/h per metre, or gpm per foot). Run before and after any treatment.
• Downhole video — useful for seeing the screen's surface condition, but it shows only the inner face. A screen can look clean on camera while the gravel pack and formation behind it are plugged.
• Water chemistry — iron, manganese, carbonate hardness, and the presence of iron bacteria indicate what type of deposit is forming.
• Construction records — screen type and slot size, gravel pack, casing, and depth determine which methods are safe and effective for that well.

The main rehabilitation methods

Every method uses energy — and sometimes chemistry — to remove deposits and restore flow. The practical difference is where that energy goes, and that determines which wells each method can actually help.

Mechanical brushing and swabbing

A brush or swab is worked through the screen to scrape deposits from the inner surface. Simple and useful for surface build-up, but its reach ends at the screen face; it does little for plugging in the gravel pack or formation.

Surging and airlifting

Moving water in and out of the screen — the same principle used in new-well development — helps loosen and remove fines. It is a valuable part of many programmes, but the energy it can apply is limited, especially in deep or heavily incrusted wells.

High-pressure jetting

A rotating jetting tool washes deposits from the slot openings with high-velocity water. It is a proven method for soft, recent deposits and post-drilling cleanup — but water velocity dissipates quickly once the jet passes the screen slot, so its effect fades within the first part of the gravel pack. See Impulse vs. high-pressure jetting for the full comparison.

Chemical treatment

Acids and dispersants dissolve mineral incrustation and biofilm. Chemistry can reach where mechanical tools cannot, but its effectiveness depends on contact time and getting the chemical to the deposit — which is why chemical treatment is often paired with a physical method that agitates the fluid through the pack and formation.

Impulse rehabilitation

An impulse generator delivers a pressure wave and an oscillating gas bubble that travel through the screen, the gravel pack, and into the near-wellbore zone — reaching the plugging a jet or brush cannot. This is the method AirShock® is built around; how it works is covered in detail below.

Why cleaning the screen alone is often not enough

This is the decisive point for choosing a method. In most aging wells the restriction is not just a film on the inner screen surface — it extends through the screen slots, into the gravel pack, and into the near-wellbore zone. Mineral incrustation and biofouling develop exactly where groundwater velocity and chemistry change, which is throughout the pack and the surrounding formation, not only against the screen wall.

A method that only cleans the inner screen face can leave a well looking clean on camera while its specific capacity barely recovers, because the blockage sits beyond that method's reach. Effective rehabilitation has to deliver energy — and, where needed, chemicals — into the gravel pack and formation. That is the physical basis of impulse rehabilitation.

The physics of impulse cleaning

An impulse generator (the AirShock® AIG) is lowered into the well on a hose and fired at 15–25 pulses per minute using compressed nitrogen or air. Each pulse produces two linked effects:

• An elastic pressure wave that propagates through the water column and continues through the screen, gravel pack, and near-wellbore zone. Unlike a water jet, a pressure wave is not stopped by the screen — it passes through it and into the surrounding aquifer.
• An oscillating gas bubble that expands and collapses, forcing water out into the formation and drawing it sharply back. This surging action mechanically breaks incrustation and biofilm and carries the loosened material into the well bore, where simultaneous airlifting or pumping removes it.

The tool works the screen at 3–5 shots per foot, so material is continuously lifted, drawn in, and extracted rather than driven deeper. The energy is matched to the well: operating pressure is chosen against the well's diameter, screen type, depth, and condition (a working range of about 225–3,000 psi), reduced when running past blank casing, with dedicated lower-energy configurations for PVC and other sensitive wells. For the engineering behind this, see The physics of impulse cleaning and Planning gas supply for an AirShock® job.

Measuring the result

Whatever method is used, the honest way to measure a rehabilitation is a step-drawdown test before and after treatment, comparing specific capacity. Video shows appearance; specific capacity shows performance. A well that recovers its flow-per-unit-drawdown has genuinely been rehabilitated; a well that only looks cleaner has not.

Documented results

The Flow Industries archive documents before/after pump-test results from wells treated with AirShock®. A few examples, each with the full data on its own page:

See all documented outcomes on the case studies page.

Where to go next

This guide is the entry point; the detail lives in the technical library:

Rehabilitation outcomes depend on the specific well — its construction, geology, condition, and correct system configuration. Every recommendation begins with the well's records and pump-test data.