Why Bores Lose Efficiency Over Time – and How to Fix It

Introduction

Even the best-designed bore will lose efficiency over time. Reduced yield, higher pumping costs, and changes in water quality are all signs of a problem that starts small — but compounds quickly.

Understanding why bores decline and how to restore them can save thousands of dollars and extend the working life of valuable groundwater infrastructure.

The Hidden Causes of Bore Efficiency Loss

1. Biofouling (Iron Bacteria Slime)

Iron bacteria are naturally present in groundwater. When they find oxygen, iron, and nutrients, they thrive — forming sticky biofilms that coat the bore screen and casing. These bacterial colonies trap iron oxides, reducing open area and restricting flow.

Typical signs include:

• Orange or rusty slime in discharge water

• Reduced flow and pressure

• Metallic odour or discoloured water

Left untreated, biofilm growth can reduce efficiency by 30–80%.

2. Mineral Encrustation

Chemical reactions in groundwater — especially where oxygen is introduced — cause iron, manganese, and calcium carbonate to precipitate as hard mineral scale.This crystalline buildup narrows the screen openings and can even cement gravel pack materials together.

3. Fine Sediment Migration

Over time, aquifer fines (very small sand and silt particles) can migrate into the bore during pumping. These particles lodge in the gravel pack or on the bore screen, causing partial blockage and turbidity issues.

The Bore Redevelopment Process

Bore redevelopment combines inspection, mechanical cleaning, and chemical treatment to restore the natural flow between the aquifer and the bore.

1. Inspection and Testing

   • Start with a downhole camera survey and flow profile to identify problem zones.

   • Record baseline data — flow rate, drawdown, turbidity, and water chemistry.

2. Mechanical Cleaning

   • Airlifting, high-pressure jetting, or brushing removes loose material, sediment, and soft biofilm layers.

   • Surging helps agitate fines and restore permeability in the gravel pack.

3. Chemical Treatment

   • Apply a bore-safe, biodegradable cleaner such as BoreSaver Ultra C PRO.

   • The product dissolves iron oxides and breaks down bacterial slime without harming the aquifer or equipment.

4. Redevelopment and Rinsing

   • Airlift or pump until water runs clear.

   • Retest the bore for yield and water quality improvements.

The results are often immediate: higher flow rates, lower drawdown, and cleaner water.

A Sustainable Solution

Regular bore maintenance and redevelopment not only improve performance but also reduce energy costs and extend equipment life.For councils, irrigators, and industry, it’s one of the most sustainable ways to manage groundwater resources.