Reverse Osmosis Water Filter Guide

If you’ve ever wondered whether your tap water is as clean as it could be, you’re not alone. Many Australians are becoming increasingly aware of what’s in their water and are seeking simple ways to make it safer, cleaner and more palatable. A reverse osmosis water filter is one of the most effective options for doing just that.

This guide explains what a reverse osmosis (RO) water filter is, how RO works and why more households are choosing it as a reliable solution for everyday drinking water.

What is a reverse osmosis (RO) water filter?

A reverse osmosis water filter is a purification system that removes impurities and contaminants from tap water by forcing it through a semi-permeable membrane. The process separates clean water from unwanted substances, including chemicals, heavy metals and microorganisms. The result is pure, great tasting water that’s safe for drinking and cooking, ideal for households seeking a simple and effective way to enhance everyday water quality.

How RO works

Reverse osmosis, or RO, uses pressure to push water through a fine membrane that separates impurities from clean water. The process is broken down into the following stages, with each filter targeting specific types of contaminants:

• Pre-filter - Removes larger particles such as dirt, rust and sediment.
• Carbon filter - Reduces chlorine, odour and organic compounds that affect taste.
• RO membrane - Filters out dissolved solids, heavy metals and microscopic impurities.
• Post-filter - Polishes the water, improving clarity and taste.
  

Each stage plays a role in removing different kinds of impurities, resulting in water that’s noticeably cleaner and better tasting.

What RO removes

An RO system targets a wide range of contaminants that can affect both the taste and safety of your water. Its fine membrane and supporting filters capture substances that ordinary filtration systems can’t, helping to create water that’s cleaner and more consistent. Common impurities removed by RO include:

• Chlorine and chemical disinfectants used in public water treatment
• Fluoride, lead, arsenic and other heavy metals
• PFAS, sometimes referred to as “forever chemicals”
• Sediment, rust, dirt and fine particles
• Microorganisms such as bacteria and parasites

Reverse osmosis is one of the few household filtration methods capable of removing a wide range of harmful contaminants, including bacteria and heavy metals. Laboratory testing and independent studies have shown that high-quality RO membranes can reduce many substances by more than 90 per cent, typically achieving 90 to 99 per cent total dissolved solids (TDS) reduction, with specific research demonstrating removal rates of up to 99 per cent for chromium and nearly 99.8 per cent for lead under optimised conditions. These results highlight why RO systems are widely regarded as one of the most effective options for producing safer, cleaner water at home.

Why RO and remineralisation matter

One effect of reverse osmosis is that it removes almost everything from water, including natural minerals, such as calcium and magnesium. While this level of purification is excellent for reducing contaminants, it can also leave the water slightly flat in taste and lower in pH.

As an added step to RO, remineralisation restores these essential minerals after the filtration process. This step helps balance the water’s pH, improves flavour and supports a more natural composition closer to spring water. Many modern RO systems now include a remineralisation cartridge or stage, ensuring that purified water not only meets high safety standards but also tastes clean and refreshing.

The result is water that’s both pure and pleasant to drink, combining the benefits of advanced filtration with the natural balance that comes from healthy mineral content.

Waste water ratio and modern improvements

A common question about reverse osmosis systems is how much water they waste during filtration. Older RO units often used more water to flush contaminants away, sometimes producing several litres of waste for every litre of filtered water.

Modern systems have made significant improvements. Advances in membrane technology and system design now allow many units to recover far more water, reducing waste and improving efficiency. Some systems can achieve ratios as low as one litre of waste for each litre of purified water produced.

While no filtration method is entirely waste-free, newer RO models are far more sustainable than their early versions. Choosing a well-designed system helps you enjoy cleaner, safer water while using less overall.

RO system installation options

Reverse osmosis systems are available in two main styles: under sink and portable bench top. Both work on the same filtration principles but suit different homes and lifestyles.

Under sink systems

Installed discreetly beneath the kitchen sink, these systems connect directly to your cold-water line and deliver purified water through a dedicated tap.

Here are its key features and advantages:

• Hidden installation keeps your bench space clear
• Permanent setup (ideal for homeowners)
• Provides a steady supply of filtered water
• Usually requires professional plumbing installation
  

Bench top systems

Compact and portable, bench top units sit on the counter and connect to most standard kitchen taps. They deliver the same purification quality as under sink models, without any permanent fittings.

These systems:

• Can be installed through DIY methods, though seeking the advice of a professional is still recommended
• Are often portable and easy to move (ideal for renters or travellers)
• Does not require plumbing
• Offer the same high-quality filtration performance
  

Choosing between the two depends on your available space, lifestyle and how permanent you want your setup to be. Regardless, both options provide clean, filtered water for everyday use.

Costs and maintenance

A reverse osmosis water filter may cost more upfront than standard filtration systems, but it offers long-term value through lower operating costs and improved water quality. Routine maintenance is straightforward, as most pre-filters and post-filters only need to be changed every 6 to 12 months, and the RO membrane can last several years, depending on usage. Replacing filters on schedule keeps the system running efficiently and ensures your water tastes fresh.

Is a reverse osmosis system right for you?

A reverse osmosis system is ideal if you:

• Want the highest level of water purity for drinking and cooking
• Prefer a reliable, long-term filtration solution
• Live in an area where tap water may contain higher levels of dissolved solids, chemicals or other impurities
• Value clean, great tasting water for your family
• Want confidence in the quality and safety of the water you drink every day
  

Reverse osmosis offers one of the most effective ways to achieve consistently pure water at home.

Pure Water Systems can help you find the perfect RO system

For over 30 years, Pure Water Systems has helped Australian families enjoy the benefits of filtered and purified water at home, at work and on the go. Our team can help you select the ideal reverse osmosis water filter for your specific needs. Simply get in touch to speak with a specialist and find the system that perfectly suits your home.