Under the sink or the whole house?
An under-sink filter looks after the water you drink. A whole house filter looks after all the water you use. The right one depends on the problem you want solved, and for plenty of homes that is the cheaper option.
BlogPublished 31 October 2026By the Eco Purify Water team
In short.
For drinking water at one tap, use an under-sink unit. For the shower, your skin, your appliances and every tap together, use a filter at the mains.
These two filters solve different problems, so it helps to start with yours. An under-sink filter treats cold water at a single tap, normally in the kitchen. A whole house filter goes in where the mains enters the property and treats everything downstream: every tap and shower, the hot water service, the washing machine and the dishwasher.
If what bothers you is how your drinking water tastes, go under-sink. It is the right fix and the cheaper one. If it is the chlorine smell in the shower, dry skin after a bath, grit in the aerators or sediment in the hot water service, a filter under the kitchen sink cannot help, because none of that water ever runs through it.
How an under-sink filter works.
Compact, affordable, and ideal for a single job.
It is a one or two cartridge unit that sits in the cupboard, connects to the cold line and feeds its own small tap on the bench, or now and then a three-way mixer. Most use a carbon block, some with a sediment pre-filter and some with a ceramic or membrane stage. A plumber can fit one in about an hour.
Its cartridges are small, and that is fine, because only the water you drink and cook with goes through them. Plan on replacing them every six to twelve months. If you want fluoride removed, this is the format that does it, using a reverse osmosis unit with a storage tank and a slow drain line.
How a whole house filter works.
One install at the inlet, built for the whole household.
It is three 20 inch housings on the main supply, in a cabinet on an outside wall, with a bypass valve and a pressure gauge. Cold water goes through one sediment stage and two carbon stages before it reaches the hot water service. A licensed plumber installs it in two to three hours and issues a plumbing compliance certificate.
Every drop the household uses goes through it, so everything is bigger. 25 mm ports and 20 inch cartridges keep pressure up with two showers and the washing machine running together, and there is enough carbon for the cartridges to last about a year, not a season.
The two compared.
What each does, what each costs, and where each comes up short.
| Under-sink | Whole house | |
|---|---|---|
| What gets filtered | Cold water at a single tap, and nothing more. | Every tap, shower and bath, the hot water service, and all your appliances. |
| Good at | Better-tasting water for drinking and cooking. Removing fluoride, if you choose a reverse osmosis unit. | Taking the chlorine smell out of showers, comfort for skin and hair, keeping sediment out of fixtures and appliances, and taste at every tap. |
| Usual installed price, Melbourne | A few hundred dollars for a carbon unit, and about twice that for reverse osmosis. | $2,499 fixed with Eco Purify, including the cabinet and your first year of cartridges. See what is covered. |
| Ongoing cost | One or two small cartridges each year. With reverse osmosis, a membrane every two to three years, plus the pre and post filters. | A set of three cartridges each year. The Care Plan delivers the set, and on the fitted plan we fit it too. |
| Flow and pressure | Its own slow tap. Reverse osmosis taps run slower again and depend on a tank. | No extra tap. Every outlet gets full flow, as long as the housings are sized properly. |
| Fluoride | Only the reverse osmosis or activated alumina versions take it out. | Stays in. Carbon does not remove fluoride. |
| Where it goes | Under the kitchen sink, in the cupboard. | In a weatherproof cabinet on an outside wall near the meter. |
| Who fits it | Any plumber. Some are sold as DIY kits with push-fit connectors. | A licensed plumber only. It is work on the mains connection, so it needs a compliance certificate. |
Under-sink suits you if.
One of these on its own is enough.
- You are renting, or you live in an apartment with a shared meter.
- Your shower is fine and you just want nicer drinking water.
- You want fluoride removed from your drinking water, which means reverse osmosis at one tap.
- Your budget is a few hundred dollars, not a few thousand.
Whole house suits you if.
An under-sink unit cannot help with any of these.
- What bugs you most is the chlorine smell in the bathroom.
- Someone at home has dry or sensitive skin that is better on holiday or on tank water.
- You are forever clearing grit from aerators and shower heads, or there is sediment in your hot water service.
- You would prefer one filter at the source over several filters at several taps to fit and look after.
- The house is yours and you plan to stay for a while.
Lots of Melbourne homes have both: a whole house system for all the water, plus a small reverse osmosis unit at the kitchen tap for fluoride-free drinking water. If fluoride matters to you, that pairing is the right one. We quote it as an add-on, because the main system does not remove fluoride and we will not pretend it does.
Common questions.
Plain answers you can use.
Which is better, a whole house filter or an under-sink filter?
Neither. They fix different things. For a few hundred dollars, an under-sink unit gives you better drinking water at one tap. A whole house unit filters every tap, shower and appliance from the mains inlet, and costs about $2,500 installed. If your problem is in the shower, only the whole house option will help.
Will an under-sink filter get rid of the chlorine smell in my shower?
No. Your shower draws from the hot water service, and the hot water service draws from the unfiltered mains. Bathroom water never goes anywhere near the kitchen filter.
Will a whole house filter improve the taste at my kitchen tap as well?
Yes. Your kitchen cold tap gets the same filtered water as every other outlet, so you do not need a separate under-sink carbon filter. The one reason to add something under the sink is fluoride removal, and that takes reverse osmosis.
Over ten years, which costs less?
Under-sink, and by a long way, since the hardware and cartridges are smaller. Comparing the two only matters once you know you want the whole house filtered. If you do not, the under-sink unit is the one to buy.
Does either one need a plumber?
The whole house installation has to be done by a licensed plumber, because it is work on the mains connection and needs a compliance certificate in Victoria. Under-sink units are normally fitted by a plumber as well, although some are sold as DIY kits.
Keep exploring.
More on the whole house option, and the price.
Eco Purify Home System: specs and inclusions
Our three-stage whole-home filter: 5 micron pleated sediment, carbon and carbon block in 20 inch WaterMark housings, inside a weatherproof cabinet. Full specifications and what comes with it.
What a whole house water filter costs in Melbourne
Our fixed installed price and each item it covers, market ranges for supply-only and installed systems, what a plumber charges on top, Care Plan cost per year against buying cartridges yourself, and what moves the price (meter location, pipe size, access).
Chlorine in your shower water
Why a Melbourne shower smells of chlorine, its effect on skin and hair, a shower filter compared with whole-home carbon filtration, and what carbon cannot remove, fluoride included.
Do water filters remove fluoride? Carbon does not, but some filters do.
Why Melbourne adds fluoride to its water, why carbon filters let it through, the technologies that do remove it (reverse osmosis, activated alumina, bone char), and the cost of doing that at one tap.
Still deciding which one?
Let us know what you do not like about your water. If an under-sink unit will sort it out, we will tell you, and you will keep a lot of money in your pocket.