Bore Water Treatment

Bore water is groundwater pumped from a well on the property. In rural Australia it is the primary water source for households and farms not connected to a town main and without enough rainfall for tank-only supply. It is also rarely safe to drink straight from the bore — even when it looks clean.

This page covers what is typically wrong with Australian bore water, the treatment stages that fix each problem, and how chemical dosing fits in.

What is in Australian bore water

Bore water draws from groundwater aquifers, which means it has been in contact with rock, soil, and organic matter for a long time. The common issues:

• Iron — gives the water a metallic taste and stains laundry, sinks, and toilets a rust-orange colour. Often invisible at the tap until air contact oxidises the dissolved iron into the visible form.
• Manganese — similar to iron but stains black or dark brown. Health concerns at higher concentrations.
• Low pH (acidic water) — corrodes copper and brass plumbing, causing pinhole leaks and blue-green staining around outlets. Common in eastern Australian sandstone aquifers.
• High hardness — calcium and magnesium dissolved out of limestone or dolomite. Scales kettles, hot-water systems, and shower heads. Not a health issue, just a maintenance one.
• Bacteria and protozoa — surface contamination of the bore casing or a shallow water table can introduce E. coli, Giardia, Cryptosporidium. Less common in deep bores, more common in shallow ones near agriculture or septic.
• Salinity — total dissolved solids from saline groundwater. A regional problem in parts of WA, SA, and inland NSW/Vic.

Get a water test before specifying any treatment. A NATA-accredited lab gives you the actual numbers — pH, hardness, iron, manganese, microbiological — for $150–$400. Without the test you are guessing.

The standard bore-water treatment train

For a typical rural household drawing from a moderate-quality bore, the treatment runs in this order:

1. Bore pump → external storage tank. Lets dissolved iron oxidise (precipitate out) before treatment. Settling time also lets sediment fall to the tank bottom.
2. Sediment pre-filter. Catches grit, sand, and the iron particles that have oxidised in the tank. 20 micron pleated polypropylene first, then 5 micron. Two stages are normal for bore water — the first traps the heavy stuff so the finer filter does not blind off in a week.
3. Chemical dosing (if needed). Chlorine for disinfection, soda ash for pH correction, or both. Dosed via a peristaltic pump into the line ahead of the next stage.
4. Carbon stage. Removes the chlorine taste added during dosing, plus any remaining organic compounds.
5. UV steriliser. Final pathogen barrier. Kills anything bacterial that survived the chlorine stage or wasn't dosed at all.

Not every bore needs every stage. A clean deep-aquifer bore with neutral pH and no measurable iron might only need sediment + carbon + UV. A shallow bore with iron, manganese, and low pH needs all five stages.

Chemical dosing — when it matters

The two most common dosing applications:

Chlorine dosing for disinfection. A peristaltic pump meters sodium hypochlorite (typically 12.5% chlorine solution) into the water line at a controlled rate to maintain a free-chlorine residual of around 0.5–1 mg/L. The chlorine then has contact time in the line or in a downstream contact tank, after which a carbon stage removes the residual taste before the water reaches the tap.

pH correction for acidic bore water. Soda ash (sodium carbonate) solution is dosed to lift pH from acidic (often 5.0–6.0) to neutral (6.5–7.5), preventing copper-pipe corrosion. The dose rate depends on the starting pH and the alkalinity of the water — a NATA test gives the right starting point, and a test pH meter at the tap confirms the dose is working.

Both setups use the same equipment — peristaltic dosing pump, day tank for the chemical, injection point on the water line.

Sizing the dosing tank

For a typical four-bedroom rural household:

• 50L tank — suits low-dose applications, trial installations, or holiday properties with light water use. Refills every one to three months.
• 100L tank — the standard for full-time household use at moderate dose rates. Refills every three to six months.
• 200L tank — larger households, higher dose rates, or anyone who wants to refill less often. Six to twelve months between refills.
• 500L tank — small-commercial, agricultural irrigation, or multi-household setups.

Dosing tanks dispensing Class 8 chemicals — which includes both sodium hypochlorite and most pH correction chemicals — generally require secondary containment under AS 1940. The simplest way to comply is an integrated bunded tank. See bunded tank regulations for the full compliance picture.

What to install yourself, what to call a plumber for

The bore pump, external storage tank, and dosing equipment can typically be installed by the property owner — they are outdoor, low-pressure, and not regulated as plumbing work in most states.

The connection from the treated-water output into the indoor mains plumbing must be done by a licensed plumber. That includes any backflow prevention, pressure regulation, or interface with existing house pipework.

Browse the pumps and tanks category for bore pumps, dosing pumps, storage tanks, and bunded chemical tanks. The rural tank water page covers the complementary case for rainwater treatment — many rural properties run both supplies in parallel.