Under-sink or benchtop water filter: which one should you buy?

Two filters with the same cartridge inside can cost very different amounts to own, and the difference is almost entirely about where they sit. Here is how to choose between under the sink and on the bench, with the real costs.

What each one is

Under-sink filters connect to the cold water line in the kitchen cupboard. Inline units (Puretec Z6 and X7, Brita’s mypure kit, and online brands such as Frizzlife and Waterdrop, which aren’t WaterMark-listed) are a single cartridge that feeds your existing tap. Housing systems (the Stefani single, twin and triple) use standard 10 inch housings, one per stage, and usually a separate small tap. Both deliver filtered water at mains pressure and never run dry.

Benchtop filters sit on the counter and connect to nothing, or nothing permanent. Gravity filters (the Stefani ceramic, the Devanti) drip through a candle or cartridge. Filtered dispensers and electric jugs (Stefani Pure Flow, Frizzlife MD40) are big jugs with a tap or a pump. Countertop reverse osmosis (Waterdrop C1S and C1H, Philips compact station) is the only benchtop option that removes fluoride and dissolved solids. On-tap filters that screw onto the spout are a third, in-between category covered in the on-tap guide.

The comparison

Prices are from Bunnings on 4 October 2026, except the Puretec Z6 cartridges (Cass Brothers $159, Puretec $232.01, each lasting six months) and the Stefani twin (Bunnings), checked 21 October 2026.

The five-year cost, honestly

Take the WaterMark-listed Stefani twin under-sink at $159, add Bunnings’ $226.60 installation and five years of cartridges at about $62 a year: about $695. Take the Stefani ceramic gravity filter at $99 with a $32.50 candle every six months: about $425. Take a Brita jug at $49.90 with a cartridge every four weeks: about $700.

So the gravity filter is cheapest to own, the under-sink is in the middle, and the jug most people start with is the dearest. The under-sink’s extra buys you filtered water at tap pressure, finer filtration, and no refilling, which is why it is the one we recommend for owners. Over ten years the install cost fades and the under-sink pulls ahead.

Who should buy under-sink

• You own the home, or have a landlord who will say yes in writing.
• You want filtered water for cooking and bottles, not just drinking, so volume matters.
• You are on tank or bore water and need a sediment stage first: the Stefani twin’s two housings do that.
• You want filtered water through your existing tap: the Puretec PureMix Z6, WaterMark-listed but dear to run at about $318 to $464 a year in cartridges.

Read the under-sink guide for the full list and the plumbing rules.

Who should buy benchtop

• You rent. Our renters’ guide goes through every no-plumbing option.
• You have no spare cupboard, or the cupboard already holds a dishwasher connection and a bin.
• You want fluoride out without a plumber: countertop reverse osmosis is the only way.
• You are on tank water and want a final polish with a ceramic candle before drinking.

The benchtop water filter guide and benchtop reverse osmosis guide have the detail.

The competition

These online under-sink units are sold as easy or no-drill installs. All of them connect to the cold line, which is licensed plumbing work, and none is on the WaterMark register, so a licensed plumber can’t install them (checked 21 October 2026).

• Waterdrop UL12A ($119.99 from Waterdrop Australia). Stands on a suction base with push fittings.
• Waterdrop TSA (Amazon Australia). Three cartridges with push fittings; only its chlorine (NSF/ANSI 42) element is certified.
• Frizzlife MK99 (Amazon Australia). Certified by IAPMO to NSF/ANSI 53 for lead and cysts, with a twist-in cartridge on your existing tap. The brand page has the detail.

The picks

Owners: the Philips FastFlow for certified, WaterMark-listed filtration, and the Stefani twin for the lowest running cost or tank water. Renters and share houses: the Stefani ceramic for near-zero running cost, the Frizzlife MD40 if you want certified lead reduction and speed, and the Waterdrop C1S if fluoride is the reason you are here.

The one trap

Choosing under-sink and then never changing the cartridge because it is out of sight. A saturated carbon cartridge stops filtering while the water keeps flowing, and an under-sink filter gives you no visual cue. If you know you are the sort of household that forgets, put the change date in your phone the day it is fitted, or buy a benchtop unit where the empty jug reminds you. The filter that gets maintained beats the better filter that does not.