Reverse Osmosis Water Filter Pros and Cons
Is Reverse Osmosis Water Worth It? Pros, Cons & What Melbourne Homeowners Should Know (2026 Guide)
Honest look at the pros and cons of reverse osmosis water filters. We cover water waste, mineral removal, taste, cost vs bottled water, and how a 7-stage system solves the common drawbacks.
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What Melbourne Homeowners Should Know About Reverse Osmosis Water Filters
Reverse osmosis is the most thorough residential water filtration technology available. It removes contaminants that standard filters can’t touch, including fluoride, dissolved salts, heavy metals, PFAS, and nitrates. Many experienced plumbers in Melbourne recommend reverse osmosis systems for homes looking for higher-quality drinking water. However, it’s not without trade-offs, and there’s plenty of misinformation online about both the benefits and the drawbacks.
We install under-sink reverse osmosis systems across Melbourne, and we think it’s only fair that our customers have a clear, honest picture before they commit. So here’s a genuine pros-and-cons breakdown, including the drawbacks and how a properly specified 7-stage system addresses the most common concerns.
Reverse Osmosis: Pros and Cons at a Glance
✓ Pros | ✗ Cons (and How They’re Addressed) |
Removes up to 99% of dissolved contaminants, including fluoride, lead, PFAS, arsenic, and dissolved salts | Produces wastewater, but modern systems are 2:1 to 3:1, far better than older 5:1 designs |
Only residential technology that effectively removes fluoride | Removes beneficial minerals, but our 7-stage system includes alkaline mineral restoration (Stage 6) |
Dramatically improves the taste noticeable from the first glass | Slower flow than tap, but the storage tank means water is ready on demand |
Eliminates bottled water costs ($1,500–$2,500/year for a Melbourne family) | Higher upfront cost than basic filters, but lower total cost than bottled water within the first year |
No electricity required, runs on mains water pressure alone | Requires filter and membrane replacement, but cartridges are straightforward to change at home |
Reduces plastic waste from single-use bottles | Treats drinking/cooking water only, not the whole house. Pair with a whole-house filter for full coverage |
See If RO Is Right for Your Home Tell us your suburb and what concerns you about your water. We’ll recommend the right system, whether that’s RO, a whole-house filter, or both. No obligation. ☎ 0420 646 641 | Get a Free Quote → |
The Pros: Why Reverse Osmosis Is Worth It
1. It Removes Contaminants That Other Filters Can’t
This is the fundamental reason RO exists for residential use. Standard carbon filters are excellent at removing chlorine, taste, odour, and organic chemicals, and they’re what we use in our whole-house filtration systems. But dissolved contaminants like fluoride, lead, arsenic, PFAS, dissolved salts, and nitrates pass straight through carbon because they’re dissolved at a molecular level.
The RO membrane filters at 0.0001 microns, fine enough to physically block these dissolved substances. For a complete breakdown of how each stage works, see our guide: What Is Reverse Osmosis and How Does It Work?
2. It’s the Only Practical Way to Remove Fluoride at Home
Melbourne’s water supply is fluoridated, and while this is a public health measure, some homeowners prefer not to consume fluoride. Carbon filters, no matter how fine, do not remove fluoride. Distillation can, but it’s impractical for daily use. Reverse osmosis is the only realistic residential option and one of the most common reasons our Melbourne customers choose it.
3. Taste Improvement Is Immediate and Obvious
We hear this consistently from customers: the difference in taste from the very first glass is noticeable. RO water tastes cleaner, smoother, and has none of the subtle chlorine or mineral flavour that Melbourne tap water carries. It also improves coffee, tea, and cooking anything where water quality affects the final result.
4. It Eliminates Bottled Water Costs
This is where the financial case for RO becomes clear:
Cost Comparison (Family of 4) | Annual Cost |
Bottled water (2L/day average household) | $1,500–$2,500/year |
RO system Year 1 (installation + cartridges) | ~$1,100 (one-off) |
RO system Year 2+ (replacement cartridges only) | ~$150–$250/year |
Break-even point | Within the first 6–12 months |
After the first year, a family replacing bottled water with RO saves approximately $1,300–$2,300 annually. Over 10 years, that’s $13,000–$23,000 in savings, plus you’ve eliminated thousands of plastic bottles from landfill.
5. No Electricity Required
An under-sink RO system runs entirely on mains water pressure. No power connection, no running costs beyond the water itself and periodic cartridge replacements. It’s completely passive once installed.
The Cons: Honest Drawbacks (and How a 7-Stage System Addresses Them)
Here’s where most RO articles either gloss over the disadvantages or blow them out of proportion. We’ll do neither. Every technology has trade-offs, and here are the real ones, and how a properly specified system manages them.
1. RO Wastes Water
The concern: RO systems produce wastewater (called concentrate or brine) as they flush contaminants to drain. Older systems could waste 5–6 litres for every litre of purified water.
The reality: Modern RO systems, including ours, operate at a much more efficient ratio of approximately 2–3 litres of wastewater per litre of purified water. Since the system only produces water when you use the dedicated drinking tap, total daily wastewater for a typical Melbourne household is roughly equivalent to a single toilet flush.
To put it in perspective: The average Melbourne household uses around 160 litres per person per day. An RO system treating drinking and cooking water adds approximately 10–15 litres per day to that total. It’s a modest increase for dramatically purer drinking water.
2. RO Removes Healthy Minerals
The concern: The RO membrane is so effective that it strips beneficial minerals like calcium, magnesium, and potassium along with the contaminants. Post-membrane water has a pH of around 6.0, which is mildly acidic and can taste flat.
The reality: This is a legitimate characteristic of the RO process, and it’s exactly why system specification matters. A basic 4 or 5-stage RO system stops after the membrane, leaving you with pure but acidic, mineral-free water.
Our 7-stage system includes Stage 6: Alkaline Mineral Restoration, which passes the purified water through mineral media that adds back calcium, magnesium, and potassium and raises the pH to approximately 8.5–9.0. You get the full contaminant removal of RO with a natural, healthy mineral balance and a smooth, pleasant taste. This is the single most important difference between a cheap RO system and a properly specified one.
3. RO Water Tastes Flat
The concern: Because basic RO systems strip minerals, the water can taste empty or flat, especially compared to mineral water.
The reality: This is only true of systems that lack a remineralisation stage. With Stage 6 restoring minerals and pH, our customers consistently describe the taste as noticeably cleaner and smoother than tap water, not flat or empty. It’s actually the taste improvement that most customers comment on first.
4. RO Is Expensive
The concern: RO systems cost more upfront than basic carbon filters or benchtop jugs.
The reality: Our 7-stage system is fully installed for $1,100 inc. GST. Ongoing cartridge replacements cost approximately $150–$250 per year. Compared to bottled water, the system pays for itself within 6–12 months. Compared to the health impact of unfiltered dissolved contaminants, it’s a modest investment in your family’s drinking water quality. For a full cost breakdown, see our water filter cost guide.
5. RO Only Filters One Tap
The concern: An under-sink RO system provides purified water at the kitchen tap only, not the whole house.
The reality: This is true, and it’s by design. RO’s slow, thorough process isn’t suited to whole-house flow rates. But most people don’t need RO-grade water in the shower or laundry. What they do need is clean water at every tap (chlorine and chloramine removal) plus the purest possible drinking water at the kitchen sink. That’s why many of our customers install both systems: a whole-house filter for every tap and an RO system for the kitchen. Combined installed price from $2,200 with 0% finance available.
For more on when each system makes sense, see: Whole House vs Under Sink Water Filter.
6. RO Requires Maintenance
The concern: Filters and the membrane need periodic replacement.
The reality: Sediment and carbon pre-filters are replaced every 6–12 months. The RO membrane lasts approximately 2–3 years. Post-filters are replaced annually. Cartridge changes are straightforward and take about 15 minutes. It’s comparable to the maintenance of any water filter and far less effort than buying and carrying home cases of bottled water every week.
The Verdict: Is Reverse Osmosis Worth It for Melbourne Homes?
RO is worth it if:
- You want fluoride removed from your drinking water
- You have concerns about dissolved contaminants (lead, PFAS, arsenic, nitrates, dissolved salts)
- You’re currently spending money on bottled water and want to stop
- You want the cleanest possible drinking water for your family, including infants and young children
- You already have a whole-house filter and want to take drinking water quality to the next level
RO is probably not necessary if:
- Your only concern is chlorine taste, and a whole-house carbon filter handles this at every tap for the same price
- You’re not concerned about fluoride or dissolved contaminants because a whole-house filter covers the main contaminants in Melbourne’s water supply.
Why the Number of Stages Matters
Not all RO systems are equal. The common drawbacks people cite, such as flat taste, mineral removal, and acidic water, are problems with basic 4 or 5-stage systems. A properly specified 7-stage system solves them:
Common Complaint | Basic 4–5 Stage RO | Our 7-Stage System |
Water tastes flat | No mineral restoration. pH ~6.0 (acidic). Flat, empty taste. | Stage 6 restores calcium, magnesium, and potassium. pH raised to 8.5–9.0. Smooth, natural taste. |
Removes healthy minerals | Membrane strips everything. No restoration. Mineral-free output. | Minerals restored post-membrane. Balanced mineral content in the final water. |
Chloramine not addressed | Basic systems may have only one carbon pre-filter. Limited chloramine reduction. | Dual carbon pre-filters (Stages 2–3) with a dedicated carbon block for chloramine, essential for Melbourne’s western suburbs. |
Bacteria risk in stored water | Basic post-filter only. No antibacterial treatment in the storage tank. | Stage 7 uses far-infrared ceramic media to inhibit bacterial growth in stored water. |
When you see negative reviews or articles about RO water tasting bad or being unhealthy, they’re almost always referring to basic systems that stop after the membrane. A 7-stage system with alkaline mineral restoration eliminates these complaints
Frequently Asked Questions
Is reverse osmosis water safe to drink every day?
Yes. RO water is among the safest drinking waters available. With our 7-stage system, minerals are restored, and pH is balanced (Stage 6), so you’re drinking water that’s both purified and nutritionally balanced for daily consumption.
Is reverse osmosis water better than bottled water?
In most cases, yes. Many bottled water brands are simply filtered municipal water, and the filtration standards for RO are typically more rigorous than those used by bottled water manufacturers. You also eliminate plastic waste and transport costs, and the water is always fresh on demand.
How much water does a reverse osmosis system waste?
Modern systems produce approximately 2–3 litres of wastewater for every litre of purified water. For a typical Melbourne household, this adds roughly 10–15 litres per day, approximately equivalent to a single toilet flush. Since the system only treats drinking and cooking water, total waste is modest.
Does RO water make good coffee and tea?
Excellent coffee and tea. By removing chlorine, dissolved salts, and off-flavours, RO water lets you taste the actual coffee or tea rather than the water. Many speciality coffee enthusiasts specifically use RO water for this reason. With Stage 6 restoring minerals, you also get the slight mineral content that helps with extraction.
Do I need RO if I already have a whole-house filter?
It depends on your priorities. A whole-house filter handles chlorine, chloramine, sediment, and chemical contaminants at every tap, but it doesn’t remove fluoride, dissolved salts, or heavy metals at a molecular level. If those matter to you, adding an RO system at the kitchen sink gives you the best of both worlds. Many of our customers choose both.
How much does an under-sink RO system cost in Melbourne?
Our 7-stage reverse osmosis system is fully installed for $1,100, including GST. That includes the system, all cartridges, dedicated drinking tap, storage tank, and licensed plumber installation. Combined with a whole-house filter from $2,200 total. 0% finance available on all systems.
How Reverse Osmosis Water Filtration Works in Residential Homes
