Bore water filtration in WA — the complete guide

Bore water vs scheme water — the key difference

Perth scheme water (from Water Corporation) is treated, tested thousands of times annually, and guaranteed to meet Australian Drinking Water Guidelines before it reaches your tap. You pay for that treatment in your water bill, and you are protected by a regulatory framework that requires compliance or escalation.

Bore water from the superficial (shallow) aquifer is none of those things. It is raw groundwater drawn directly from under your property. It has not been treated, has not been tested by any utility, and there is no regulatory body guaranteeing its quality. What it contains depends entirely on the geology, land use history, and hydrology of your specific location.

This is not a reason to avoid bores — approximately one in four Perth gardens use bores for irrigation, and many are entirely suitable for that purpose. But it is a reason to test before making any assumptions, and to understand that "bore water" describes a source, not a quality standard.

The three main problems with Perth bore water

Most Perth bore water issues fall into three categories. Understanding which one — or which combination — you're dealing with is the starting point for any treatment decision.

1. Iron and iron staining

Iron is the most common bore water problem in Perth. The superficial aquifer in many Perth suburbs sits above iron-rich geology, and groundwater picks up dissolved iron as it moves through this material. The iron is dissolved (invisible) when it leaves your bore pump — but when it contacts oxygen in air or on surfaces, it oxidises and precipitates as iron oxide: the orange-brown rust staining you see on paths, walls, fences, sprinkler heads, and laundry.

Iron concentration thresholds that matter in practice:

Iron level	What you notice	Treatment required
Below 0.25 mg/L	None — aesthetically acceptable	No treatment needed
0.25–2 mg/L	Taste and odour — mild staining over time	Specialty inline filter may suffice
2–5 mg/L	Noticeable staining on sprayed surfaces	KDF/catalytic media filter with regular backwash
5–20 mg/L	Significant staining — sprinkler head clogging begins	Aeration system + catalytic sand filter required
Above 20 mg/L	Severe staining, pipe fouling, pump damage risk	Chlorine micro-dosing + aeration + dual sand filters

Iron concentrations vary dramatically by suburb. Areas like Joondalup and Mt Claremont have some of the highest iron levels recorded in Perth's superficial aquifer — some bores above 37 mg/L have been measured in these zones. Coastal areas near wetlands or low-lying land tend to have higher iron because the shallow, anaerobic conditions near the water table favour dissolved iron. By contrast, areas like Kensington can have very low iron and relatively clear bore water.

The critical point about iron removal: standard inline water filters are not iron removal systems. A carbon block or sediment filter designed for scheme water will become saturated with iron within days if the concentration is above a few mg/L. Iron removal above 5 mg/L requires an aeration-based system that oxidises the dissolved iron before it reaches any filter — converting it to a particle that can then be captured in a catalytic sand bed.

2. Iron bacteria

Iron bacteria are microorganisms that feed on dissolved iron in groundwater. They produce a rust-coloured, slimy biofilm that coats sprinkler heads, pipe interiors, bore casings, and pump components. This biofilm is the cause of the brownish slime that Perth bore owners often notice inside hose fittings and on irrigation equipment — and it accelerates the corrosion of pumps and pipes when left untreated.

Iron bacteria and dissolved iron often occur together, but they are separate problems requiring separate treatment components. You can have iron bacteria without high dissolved iron, and vice versa. Iron bacteria are not generally considered a health risk at typical concentrations, but they are a significant maintenance and equipment problem.

Treatment for iron bacteria involves:

• Shock chlorination of the bore and distribution system to kill existing bacterial colonies
• Ongoing chlorine micro-dosing to prevent re-establishment — iron bacteria return quickly without ongoing disinfection
• Removing iron from the water (which removes the bacteria's food source) as a long-term control measure

3. Salinity

Salinity in Perth bore water is caused by the natural presence of salt in the coastal plain aquifer and, near the coast or rivers, saltwater intrusion. Bore water near the Swan River, the coast, or low-lying estuarine areas can have elevated electrical conductivity and a distinctly salty taste or feel.

Salinity cannot be removed by standard filtration, KDF, carbon block, or iron removal systems. The only effective treatment is reverse osmosis, which removes dissolved salts through membrane filtration. For irrigation-only bore water, a salinity level below approximately 800 mg/L TDS is generally acceptable for most Perth garden plants — above this, salt damage to turf and plants becomes a consideration.

Some Perth suburbs are explicitly flagged by DWER as unsuitable for garden bores due to saltwater intrusion — the Cottesloe Peninsula and areas around Secret Harbour and Port Kennedy are examples. Check the Perth groundwater map at the DWER website before drilling.

Testing first — what to test for

Before investing in any bore water treatment system, test your water. A water treatment system designed for the wrong problem will not solve your issue and may create new ones. This is not a situation where buying a "comprehensive" filter is a safe default — you need data.

A NATA-accredited laboratory water test costs $150–$400 depending on the panel. For bore water used for irrigation only, a standard panel covers:

• pH, electrical conductivity (salinity), TDS
• Iron, manganese (both dissolved and total)
• Hardness (calcium and magnesium)
• Sodium and chloride (salinity indicators)
• E. coli and total coliforms (bacteria)
• Hydrogen sulphide (rotten egg smell indicator)

For bore water intended for drinking or food preparation, the panel must also include nitrates, heavy metals, and — depending on land use history near your bore — an agricultural chemical screen or PFAS panel.

Perth aquifer rules — what you can and can't bore

Perth's groundwater sits in three distinct aquifer layers, and only one is accessible for residential bores:

• Superficial aquifer: The shallow, unconfined aquifer closest to the surface. This is the only aquifer licensed for residential (non-commercial) bore use without an approved groundwater licence. Maximum bore depth is limited to the base of the superficial aquifer at your property — check via the Perth groundwater map tool (wa.gov.au).
• Leederville aquifer: A confined aquifer below the superficial layer, separated by confining clay layers. Licensed for Water Corporation use. Not available for residential bores.
• Yarragadee aquifer: The deepest and most reliable aquifer — a vast ancient groundwater system. Used by Water Corporation and by Aqwest (Bunbury) for scheme supply. Not available for residential bores.

The bore depth permitted on your property without a licence depends on local geology — use the Perth groundwater map to find the allowable depth before drilling. Bores must be constructed by an ADITC-accredited driller and meet the Minimum Construction Requirements for Water Bores in Australia (4th Edition, 2020).

Treatment matched to problem

Low iron (under 5 mg/L) — inline filter approach

If your test shows iron below 5 mg/L and no iron bacteria, a catalytic KDF or specialty iron-reduction filter inline with your bore pump may be sufficient. These systems use a zinc-copper redox media that oxidises dissolved iron and manganese, capturing it in the media. They require regular backwashing to remove captured iron. NSF-certified media is preferable. Expect to spend $500–$1,500 installed for a residential unit.

Medium to high iron (5–37+ mg/L) — aeration system required

Above 5 mg/L, you need aeration before filtration. The aeration stage injects air into the raw bore water, oxidising dissolved ferrous iron (Fe²⁺) into insoluble ferric iron (Fe³⁺) particles before they enter the filter bed. The catalytic sand filter then captures these particles. Most Perth residential aeration systems use a venturi or diffuser pump to introduce air, followed by a sand bed containing catalytic media matched to your specific iron concentration and pH.

At very high concentrations (above 20 mg/L), chlorine micro-dosing is added before the aeration chamber to ensure complete oxidation and to control iron bacteria simultaneously. The ongoing cost for chlorine dosing in these systems is approximately $200 per year in chemical costs. Sand filters require periodic backwashing — this can be automated on a timer. Installed cost for a medium-high iron residential system: $3,000–$6,000.

Iron bacteria — shock chlorination plus ongoing dosing

Treat the bore first with shock chlorination (high-concentration chlorine solution injected into the bore and left to contact for 12–24 hours, then flushed). This kills existing bacterial colonies. Follow with ongoing chlorine micro-dosing to the irrigation line to prevent re-establishment. If you also have iron, the iron treatment system (aeration + sand filter) combined with chlorine dosing addresses both problems together.

Salinity — reverse osmosis only

If your bore water test shows elevated electrical conductivity (above ~800–1000 µS/cm for irrigation, lower for drinking), the only solution is RO. A whole-bore RO system is expensive ($5,000+) and wastes 2–4 litres per litre produced. For most irrigation uses, if the water is excessively saline the more practical solution is to assess whether the bore location can be moved to a less saline part of the aquifer, or whether the bore is viable at all.

Drinking water use — multi-barrier system

If you want to use bore water for drinking, the treatment system must address all contaminants identified in your potable water panel. A typical multi-barrier system for Perth bore water used for drinking includes: sediment pre-filter → iron removal (aeration or KDF) → UV disinfection → under-sink RO for final drinking water. The UV stage kills bacteria and viruses. The RO stage removes dissolved contaminants, nitrates, heavy metals, and any residual salinity. This is a significant installation and the ongoing maintenance is higher than scheme water filtration. Budget $4,000–$8,000+ installed for a comprehensive drinking-standard bore treatment system.

Can I use bore water instead of scheme water?

Perth bores are licensed for outdoor (garden) irrigation, which is their primary use — reducing scheme water consumption for lawns and gardens. Using bore water for drinking, cooking, bathing, or indoor purposes requires that the water meets potable standards and that the bore infrastructure complies with health requirements.

In practice, most Perth residential bore setups are not designed or approved for drinking use. The pump, pipe materials, and storage (if any) may not meet potable water standards. If you want to use bore water for drinking, consult the WA Department of Health and get appropriate NATA-accredited testing before proceeding.

For garden irrigation: a properly treated bore is an excellent resource — offsetting scheme water use significantly and reducing water bills. For the typical Perth quarter-acre block with a healthy bore and appropriate iron treatment, bore water can supply all outdoor irrigation needs.

Maintenance you cannot skip

Bore water treatment systems require more active maintenance than scheme water systems. Key maintenance items:

• Sand filter backwash: Required regularly (weekly to monthly depending on iron load) to remove captured iron from the media bed. Automated backwash controllers are strongly recommended.
• Chlorine supply replenishment: If using a dosing system, the chlorine tank needs refilling — typically monthly for a residential property.
• UV lamp replacement: If using UV disinfection, the lamp degrades over time and must be replaced annually regardless of appearance.
• Annual water re-test: Bore water quality can change over time — seasonal, due to nearby land use changes, or aquifer level fluctuations. Annual testing is good practice.
• Pump servicing: Bore pumps should be inspected regularly. Iron bacteria accumulation on pump impellers is a common cause of reduced flow and pump failure.