Water Softener vs Water Filter Australia: Which Do You Actually Need?

A water softener and a water filter are not the same thing. They are different technologies solving different problems, and confusing the two is one of the most common mistakes Australian homeowners make when they are trying to improve their water. A softener removes hardness minerals — calcium and magnesium — via ion exchange. A filter removes contaminants — chloramine, PFAS, fluoride, heavy metals. One does not do the other’s job. If you are in Perth or Adelaide, there is a real chance you need both. Here is how to work out which one applies to your situation.

What Does a Water Softener Do?

A water softener uses ion exchange to remove calcium and magnesium from your water supply. Water passes through a resin tank loaded with sodium ions. The resin grabs the calcium and magnesium ions and releases sodium ions in exchange. What comes out is chemically “soft” — low in hardness minerals.

The practical result: no limescale building up inside your hot water system, dishwasher, washing machine, and shower heads. Appliances last longer. Soap and shampoo lather properly. Your skin and hair feel less dry after showering — not because the water is cleaner, but because hard minerals are no longer stripping your skin’s natural oils or leaving residue on your hair.

The resin tank regenerates periodically using salt (sodium chloride or potassium chloride), which flushes out the captured calcium and magnesium and resets the resin for the next cycle. Running cost is mostly salt, typically $150–$300 per year depending on water hardness and household size.

What a softener does NOT do: it does not remove chloramine, PFAS, fluoride, heavy metals, bacteria, or any chemical contaminants. The water coming out of a softener may be cleaner in terms of mineral scale, but it is not safer to drink in any meaningful sense. If your city uses chloramine (Brisbane, Sydney, Adelaide, Perth, Darwin), your softened water still contains chloramine. You still need a filter for drinking water.

The Pure Water Systems Water Softener ($2,395–$3,495) is an Australian-designed unit sized for household demand, with automatic regeneration and a 10-year resin warranty.

What Does a Water Filter Do?

A water filter removes chemical contaminants — but exactly which contaminants depends on the type of filter. These are not interchangeable systems.

Carbon block filters (including catalytic carbon) remove chlorine, chloramine, VOCs, herbicides, pesticides, and some heavy metals. They improve taste and odour significantly. Catalytic carbon is the only carbon media that effectively removes chloramine — standard granular activated carbon (GAC) does not break chloramine down efficiently. If you are in Brisbane, Sydney, Adelaide, Perth, or Darwin and buying a carbon filter, confirm it uses catalytic carbon or a dedicated chloramine-reduction stage.

What carbon filters do NOT remove: fluoride, nitrates, dissolved minerals (hardness), PFAS, or most heavy metals at meaningful reduction rates. A carbon filter does nothing to address limescale or water hardness.

Reverse osmosis (RO) systems push water through a semi-permeable membrane at pressure. This removes virtually everything — fluoride, PFAS, nitrates, heavy metals (lead, arsenic), dissolved TDS, chloramine, and yes, hardness minerals too. RO is the most thorough filtration available for residential drinking water.

The tradeoff: RO systems waste some water in the process (though modern systems like the EcoHero-50 membrane are significantly more efficient than older units), they require filter cartridge changes every 6–12 months, and they filter at low flow rates — they are drinking-water point-of-use systems, not whole-house systems.

The EcoHero 5-Stage Under Sink RO ($1,009–$1,059) is NSF 58 certified, WaterMark AS3497 compliant, and uses the EcoHero-50 membrane with 300% better water efficiency than standard RO units. For a carbon-only option without fluoride removal, the PWS Luxe Collection ($875–$995) is a dual-action high-flow system suited to chloramine cities.

Side-by-Side Comparison Table

Decision Guide: What Do You Actually Need?

The right answer depends on where you live and what your water actually contains. Here is a practical breakdown by city.

Perth and Adelaide have the strongest case for both systems. Perth water sits around 180 mg/L CaCO3 hardness — the hardest capital city supply in Australia — with TDS around 170 mg/L. Adelaide averages 140 mg/L hardness with TDS reaching 400 mg/L. Both cities use chloramine for disinfection. If you are in either city and you own your home, a whole-house water softener protects your hot water system, washing machine, and dishwasher from scale while improving skin and hair feel. You then need an RO system at the drinking tap to handle chloramine, PFAS, and fluoride that the softener leaves behind.

Brisbane and Sydney have moderate hardness (Brisbane 80–120 mg/L, Sydney 50–80 mg/L) that causes some scaling but is less aggressive than Perth or Adelaide. Both cities use chloramine. For most Brisbane and Sydney households, a good under-sink RO or catalytic carbon filter addresses the main drinking water concerns. A softener is optional — worth considering if you are seeing visible limescale, but not urgent in the way it is for Perth homeowners.

Melbourne and Hobart have very soft water — Melbourne averages around 25 mg/L CaCO3 — and use standard chlorine (not chloramine). A standard carbon block filter is sufficient for most households: it handles chlorine, improves taste, and removes common VOCs. RO is worth adding only if you specifically want fluoride removal. A softener is rarely warranted in Melbourne given how soft the supply is.

Rural and tank water users face different issues: low hardness but potential bacteria, sediment, and agricultural runoff. RO is the right primary filter for drinking water. Add UV disinfection if you are on rainwater that may have biological contamination.

Renters cannot install a whole-house softener, but can add a benchtop or portable RO for drinking water.

Softener + RO Combo: When You Need Both

If you are in Perth or Adelaide, the softener-plus-RO combination is not luxury — it is the practical answer to two separate problems that happen to exist in the same water supply.

The setup works in series. A whole-house water softener is installed at the mains entry point. Every tap, shower, and appliance in the house receives softened water — scale-free, gentler on skin and hair, easier on heating elements and seals. The softener does not touch the chemical contaminants.

At the kitchen sink, an under-sink RO system handles the drinking water. The RO membrane removes fluoride, chloramine, PFAS, nitrates, and dissolved TDS. Because the softener has already removed the calcium and magnesium, the RO membrane lasts longer — hard water is one of the primary causes of premature membrane fouling. The two systems complement each other directly.

Cost breakdown for a Perth household:

• PWS Water Softener: $2,395–$3,495 installed, plus $150–$300/year in salt
• EcoHero 5-Stage RO: $1,009–$1,059 installed, plus $120–$200/year in filter cartridges
• Total upfront: roughly $3,400–$4,500 depending on installation complexity

For most Perth and Adelaide homeowners who are dealing with appliance scale and want clean drinking water, this is a one-time setup that solves both issues properly.

Frequently Asked Questions

Do I need a water softener or a water filter for Brisbane?

In Brisbane, water hardness is moderate (80–120 mg/L CaCO3) — enough to cause some limescale but not at the severe level seen in Perth or Adelaide. The more pressing issue is chloramine, which Brisbane Water uses for disinfection and which standard carbon filters do not remove effectively. For most Brisbane households, a good under-sink RO system or a catalytic carbon filter addresses the main drinking water concerns. A softener is optional — worth considering if you are seeing visible scale on taps and shower screens — but not the priority that it is in harder water cities.

Can a water filter replace a water softener?

No. A water filter (carbon or RO) and a water softener solve different problems. A carbon filter removes chemical contaminants like chloramine and VOCs but does not remove calcium and magnesium ions responsible for water hardness and scale. An RO system does remove hardness minerals alongside contaminants, but it is a point-of-use drinking water system — it filters only the water at one tap, not the water running through your hot water system, washing machine, and dishwasher. If you need whole-house scale protection, you need a softener. If you need safe drinking water, you need a filter. In hard water cities, you need both.

Does reverse osmosis remove water hardness?

Yes, an RO system removes calcium and magnesium ions along with everything else — a good RO membrane will reduce TDS by 90% or more, which includes hardness minerals. However, RO systems are under-sink point-of-use units producing filtered water only at the connected tap, typically at low flow rates (a few litres per hour). They are not practical as a whole-house hardness solution. If you want scale protection for your entire plumbing system, appliances, and shower, you need a dedicated whole-house water softener. RO is for drinking water; a softener is for protecting your home infrastructure.

Is soft water safe to drink?

Yes, softened water is safe to drink for most people. The ion exchange process replaces calcium and magnesium with trace amounts of sodium. For a typical household water supply, the sodium increase from softening is small — generally 10–40 mg/L depending on original hardness — which is well within safe drinking limits for healthy adults. People on sodium-restricted diets prescribed by a doctor may prefer to use an RO system at the drinking tap (RO removes the sodium too). Beyond sodium, softened water still contains whatever chemical contaminants were in the original supply — chloramine, fluoride, PFAS. For those, you need a filter in addition to the softener.

What’s the best water softener brand in Australia?

Pure Water Systems is one of the best-established Australian suppliers of residential water softeners, offering units designed and sized for Australian water hardness conditions and local plumbing standards. Their water softener range runs from $2,395 to $3,495 and includes a 10-year resin warranty with automatic regeneration. When evaluating any water softener brand, check for Australian WaterMark certification, local technical support, and salt availability in your area. Avoid generic imported units without local support — the installation and ongoing servicing matters as much as the unit itself.

Do I need a water softener in Melbourne?

Almost certainly not. Melbourne has some of the softest tap water of any Australian capital city, averaging around 25 mg/L CaCO3. At that hardness level, there is negligible scaling on appliances, and there is no practical benefit to running a softener. Melbourne water also uses standard chlorine rather than chloramine, so a standard carbon block filter is sufficient for most households wanting to improve taste and remove chlorine. If you want fluoride removed from your drinking water, an under-sink RO system is the upgrade to consider — not a softener.

What’s the difference between a water softener and an RO system?

A water softener works via ion exchange at whole-house scale: it removes calcium and magnesium ions that cause hardness and scale, replacing them with sodium ions. It does not remove chemical contaminants. An RO system uses a semi-permeable membrane at point-of-use (usually a single kitchen tap) to remove dissolved solids including contaminants, fluoride, PFAS, heavy metals, and yes, hardness minerals too — but only from the small volume of drinking water you draw from that tap. In short: a softener protects your plumbing and appliances from scale throughout your home; an RO system gives you clean, low-TDS drinking water at one point. For hard water cities with chloramine, you use them together.

Written by Jayce Love

Former Royal Australian Navy Clearance Diver and TAG-E counter-terrorism operator. Founded Clean and Native to apply the same rigorous thinking to the home environment.

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