Under-Sink Water Filter System or Reverse Osmosis: Which Is Right for Your Home?

How to choose between under-sink filtration and reverse osmosis

Choosing between an under sink water filter system and a reverse osmosis system comes down to what you’ve noticed about your water and what you want to improve. 

Both systems are installed under the sink and connect to your mains water supply. The difference is in how each system filters water and which contaminants they are designed to reduce. 

For most homes on municipal mains water, a standard sediment and carbon under sink water filter system is enough. Where there are specific concerns such as PFAS, fluoride or heavy metals, reverse osmosis goes further.

This guide helps you decide which option fits your home. 

What a standard under-sink filter is best for

A standard under sink water filter system uses sediment and activated carbon filtration to improve drinking water at the kitchen tap. It reduces chlorine and chlorine by-products, contaminants that affect taste and smell, and fine sediment like sand and grit.

For most WA homes on municipal mains water, improving the taste and odour of tap water is the key reason for filtering water. 

Filtered drinking water tastes cleaner, smells better and is more pleasant to use for tea, coffee and cooking.

Where there are specific water concerns such as lead, copper or scale, under-sink systems can be configured with specialist cartridge options to address these specific issues. 

Most Perth households start with a standard under sink water filter system, either a Twin Filter System or single combined sediment and carbon filter system, like the Maxiflow or Mixerflow Filter Systems.

If you are still comparing options, our under-sink and on-tap filter range shows the full selection we install and service across Perth and regional WA.

Filter cartridges typically need replacing every 6 to 12 months to protect water quality and we can manage servicing and maintenance after installation so your filter system always performs how it should and you water always taste great.

What reverse osmosis is best for

A reverse osmosis (RO) system filters water through a very fine membrane under pressure, after it has been passed through sediment and carbon filters.

This additional filtration stage removes up to 99% of contaminants, chemicals and minerals, including PFAS, fluoride, heavy metals and total dissolved solids. 

This makes RO the best solution if you live in an area with poor quality source water or rely on bore water. 

There are also practical differences. Reverse osmosis filtering is slower than a standard under sink filter, often uses a small storage tank, and can use up to three litres of source water for every litre of pure water it produces.

It’s worth remembering this water can be collected and used for your laundry, washing up and watering the garden to minimise waste. RO membranes typically last two to four years, and the sediment and carbon pre-filters should be replaced every 6 to 12 months.

PFAS is more commonly a concern for bore or dam water than mains water. A 2019 DWER investigation found PFAS in a high proportion of Perth groundwater sampling locations. Bore water users and households near known contamination sites face a different risk profile to those on scheme water.

The Commonwealth’s PFAS National Environmental Management Plan was updated in December 2024 to reflect tighter risk thresholds. Where bore water or a specific contaminant concern exists, reverse osmosis may be appropriate.

In the Pilbara and parts of regional WA, and for homes relying on bore or dam water with higher sediment and mineral levels, RO is the most popular water filtration system.

Our reverse osmosis filter systems range covers the options we install and service across WA.

Under-Sink Filter vs Reverse Osmosis Comparison

To improve everyday drinking water, a standard under sink water filter system is usually the right starting point for most Perth homes.

A reverse osmosis system is better suited where water quality can vary or there are specific concerns about contaminants like PFAS, bacteria and viruses. 

Water2water installs and services under-sink and RO filter systems and, because we’re not tied to any manufacturers, we will always recommend the most cost-effective filtration based on the quality of your water, your budget and your household water needs.

For a more technical breakdown, our RO vs Twin Filter guide explains the differences in detail.

We offer free standard installation on many under sink filtration systems for domestic customers in Perth and many areas of regional WA. For more details, see our installation service to check eligibility and areas covered. 

If you want to purify water throughout your home, our guide on water filtration for your home explains all the options.