Whole House or Under Sink Water Filter: Which Do You Need?
An under-sink filter treats the water you drink at one tap. A whole house filter treats every tap, shower and appliance, but it is not the stronger choice for everything. Here is where each one sits, what each removes, who each suits, a side-by-side table, a simple way to decide, and why plenty of homes end up with both.
Many homes pair the two: a whole house carbon filter for every tap and shower, and an under-sink system at the kitchen for drinking water. Both connect to your water supply, so in NSW both need a WaterMark certified product fitted by a licensed plumber.
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Talk to a licensed plumber about the right filterWhere Each Filter Sits
The difference starts with where the filter goes. Puretec puts it simply: a whole house system treats all the water coming into your home, while an under-sink system gives targeted filtration for just one tap, typically in the kitchen.
Where each filter sits, and which taps get filtered water
Placement as described by Puretec (a whole house system goes where the mains supply enters your home) and Pure Water Systems (point-of-use filters, like under-sink units, treat water at one specific tap).
What Each One Removes
Both kinds usually use carbon, so both take out the chlorine taste and smell. They part ways on reach, on PFAS and, for tank water, on germs.
Chlorine Taste and Smell
Carbon removes it in both. Puretec says its whole house FilterWall reduces chlorine by up to 98%. The difference is reach: whole house does every tap and shower, under-sink does the kitchen drinking tap.Source: Puretec FilterWall F Series
Sediment
Whole house systems such as Puretec's FilterWall, All Home Filtration's system and Select Plumbing and Gas's HP3 include a sediment stage, which traps dirt, rust, sand and silt before it reaches your taps and appliances.Sources: Puretec; All Home Filtration; Select Plumbing and Gas; Awesome Water
PFAS
A 2020 study found under-sink dual-stage and reverse osmosis filters removed the PFAS tested almost completely. Other carbon filters were variable, and whole house carbon systems had higher PFAS after the filter in four of eight.Source: Herkert et al., Environmental Science and Technology Letters, 2020
Germs in Tank Water
NSW Health notes that not all filters remove or inactivate harmful microorganisms, and that an additional disinfection unit may be necessary. For tank water used for drinking it lists UV disinfection, and filters that meet a standard such as AS/NZS 4348 or NSF/ANSI 53.Source: NSW Health, rainwater tanks
PFAS removal found in home filters
Herkert et al., Environmental Science and Technology Letters, 2020: filters tested in 73 homes in North Carolina, USA. "Other carbon filters" covers jugs, tap-mounted, fridge and under-sink carbon block filters. Sydney Water reports PFAS below the national guideline values at every plant, so this is about choice, not a safety fix.
Side by Side
How the two compare on the things people ask about. Prices are published market ranges from the named businesses, not Mr Splash prices.
| What you get | Under-sink filter | Whole house filter |
|---|---|---|
| Where it filters | One tap, usually the kitchen | Every tap, shower and appliance |
| Chlorine taste and smell | Yes | Yes |
| Shower and bath water | No | Yes |
| PFAS in drinking water | Near complete with RO or dual-stage | Variable |
| Where it goes | The cabinet under the kitchen sink | On the main, often an outside wall |
| Cartridges | Smaller, at one tap | Larger, changed less often per litre |
| Published labour to install | $185 to $470 | $300 to $900 |
| Published system price | Reverse osmosis listed from $799 | Installed prices from $2,995 |
| Needs a licensed plumber | Yes | Yes |
Who Each One Suits
Most people fit one of these five situations.
You Just Want Better Drinking Water
An under-sink filter puts filtered water where you fill the kettle and the glass, at a lower published price than a whole house system. For PFAS, choose reverse osmosis or dual-stage.
You Notice Chlorine in the Shower
Only a whole house filter treats the shower and bath. Some people find their skin and hair feel less dry once the chlorine is gone. The research on chlorine and skin is still uncertain, so we won't promise it will fix a skin condition.
You Are on Tank Water
Think about germs, not just taste. For tank water used for drinking, NSW Health lists boiling, chlorination or a properly sized UV unit. Sediment and carbon filtration then look after grit and taste across the house.Source: NSW Health, rainwater tanks
You Rent
A plumbed-in filter is a change to the property. NSW rules say you can make changes if your lease allows it or your landlord gives written permission, water filters are not on the list of minor changes a landlord cannot unreasonably refuse, and unless the landlord agrees to pay, you pay. An under-sink filter is the smaller ask.Source: NSW Government, making changes to a rental property
You Are Worried About PFAS
Choose an under-sink reverse osmosis or dual-stage filter for drinking water. NHMRC says PFAS exposure from showering and bathing is negligible, so a whole house system adds little for PFAS.Sources: Herkert et al. 2020; NHMRC
A Simple Way to Decide
Answer these in order. Most homes have their answer by the third question.
Which filter? Four questions
No: go to question 2
No: go to question 3
No: go to question 4
Renting? Get your landlord's written permission before anything is plumbed in. Sources: NSW Health (tank water), Herkert et al. 2020 (PFAS), NHMRC (supplies below the guideline values need no extra home treatment), NSW Government (rental changes).
Why Many Homes Do Both
The two are not rivals. They do different jobs, and specialists sell them together.
Pure Water Systems says most households get the best result from running a whole house system alongside a point-of-use filter in the kitchen, and it recommends pairing the two for an extra layer of protection at the kitchen tap. Great Water Filters sells its whole house system with reverse osmosis as a bundle, and All Home Filtration sells both.
The pairing splits the work sensibly: a whole house carbon filter for the chlorine taste and smell at every tap and shower, and an under-sink reverse osmosis or dual-stage system for the water you drink. The trade-off is two sets of cartridges to change, so set both schedules when they go in.
Installing Either One in NSW
Whichever you choose, the rules are the same.
Mr Splash fits both, with free quotes, one fixed price agreed before any work starts, a lifetime guarantee on workmanship and 0% interest payment plans. See whole house water filters or under-sink and filter tap installation.
- Licensed plumber, certified product. WaterMark rules say a product must be certified before it can be installed and must be installed by a licensed plumbing practitioner. That covers under-sink units and whole house systems alike.
- Whole house: on the main. It goes where the supply enters the home, with isolation valves and a bypass so it can be serviced without cutting water to the house (HG PureWater).
- Under-sink: in the kitchen cabinet. It sits under the sink and feeds the drinking tap.
- Cartridges on a schedule. Both need changing. A neglected filter can trap deposits that promote bacteria growth (Scientific Reports, 2018), so set the schedule when it is fitted.
Whole House or Under Sink FAQs
Is a whole house filter better than an under sink filter?
Not better, different. A whole house filter treats every tap and shower; an under-sink filter treats the water you drink. For PFAS, an under-sink reverse osmosis or dual-stage filter is the stronger choice.
Do I need an under sink filter if I have a whole house filter?
Only if you want more for your drinking water than chlorine taste and smell removed. Pure Water Systems recommends pairing the two, and under-sink reverse osmosis or dual-stage is the proven option for PFAS.
Which water filter is best for PFAS?
Under-sink reverse osmosis or dual-stage. A 2020 study found they removed the PFAS tested almost completely, while whole house carbon systems were variable.
Does a whole house water filter filter the shower?
Yes. It sits on the main, so every shower, bath and tap gets filtered water. An under-sink filter only treats its own tap.
Can renters install an under sink water filter?
With permission. NSW rules let renters make changes if the lease allows it or the landlord gives written permission, and water filters are not on the list of minor changes a landlord cannot unreasonably refuse.
Which filter is best for tank water?
It depends on the use. For drinking tank water, NSW Health's advice covers disinfection such as UV and filters that meet a recognised standard. Sediment and carbon filtration look after grit and taste across the house.
Do both types need a plumber?
Yes. Anything connected to your water supply in NSW needs a WaterMark certified product installed by a licensed plumber.
Related: Whole house water filters · Water filter installation · Whole house water filter cost · Whole house water filter disadvantages · Filter tap or under sink? · Is Sydney tap water safe to drink?
