u/wellness-nek-level

i got nerd sniped by this.
the room size rating printed on the box is calculated by the manufacturer. so basically made up bs and no standard for how they do it, so a unit “rated for 500 sq ft” from one brand and another “rated for 500 sq ft” from a different brand can perform completely differently.

the only actually means something is CADR - Clean Air Delivery Rate. the simple rule is your smoke CADR should match or exceed your room size in square feet. smoke is used because its the hardest particle type to capture - if it handles smoke it handles dust and pollen. Done.

oh another lil sneaky trick brands sometimes advertise pollen CADR because its the highest of the three numbers. smoke CADR is what you want to compare.

for bedrooms specifically i’d size up - a unit rated exactly for your room runs on high all night. one rated for double your room runs on low or medium, which means quieter and longer filter life.

one more hot chip (I’m full of them) - HEPA captures particles but does nothing for gases, VOCs, or smoke smell. for that you need activated carbon as a separate stage. thin carbon pre-filters on cheap units are mostly decorative. if youre dealing with bushfire smoke, cooking smells, or new furniture off-gassing, carbon matters as much as the HEPA.

and turn the ioniser off. it doesnt filter anything, just moves particles to your walls, and some produce ozone.

ok this applies to any country really. but i;ve noticed this seems to be a repeated convo so a lil bit of education could help on filter selection so you dont waste your time and filter the wrong thing for your area.

chloramine vs free chlorine - most AU capitals use chloramine (Brisbane, Sydney, Perth, Adelaide, Gold Coast, Darwin). Melbourne and Hobart use free chlorine. this distinction is huge because standard carbon filters (Brita, most benchtop jugs) handle free chlorine fine but do almost nothing for chloramine. if youre in a chloramine city and running a standard carbon filter, youre mostly filtering for taste on chlorine that isnt there.

for chloramine you need catalytic carbon or RO.

fluoride - only RO (90ish% removal) or activated alumina reliably removes fluoride. carbon cannot and i see a lot fo people just saying get any ol filter and it does the job. if fluoride removal is your goal, a standard filter wont get you there.

PFAS (yes, forever chemicals) only RO with NSF 58 certification or NSF P473 certified carbon removes PFAS reliably. relevant if youre near defence sites or known contamination areas (Williamtown NSW, Oakey QLD, Katherine NT, Pearce WA).

arsenic bore water concern in WA, NT, SA, western QLD. not a capital city mains concern.

short version

• Brisbane, Sydney, Perth, Adelaide, Gold Coast, Darwin = chloramine. need catalytic carbon or RO
• Melbourne, Hobart = free chlorine. standard carbon filter works fine
• fluoride removal = RO or activated alumina only
• PFAS = RO (NSF 58) or NSF P473 carbon only

Of course this is Australia focussed, but you can easily search the common chemcial/compound thats in your local water supply that you want to focus your filter selection on.

Happy filtering

just genuinely curious what other renters do about water filtration. do you bother at all, go countertop, or has anyone actually installed something under the sink? keen to hear real experiences.

We moved into a place on the Gold Coast last year and the tap water tasted off, so I grabbed one of those benchtop filter jugs from Bunnings.

Felt better drinking it for a few months. Then I bought a $15 TDS meter to see how well the thing was actually working and the reading was basically identical to straight tap. 370 before, 360 after. I'd spent two hundred bucks on a placebo.

Went down a rabbit hole after that. Turns out the filter I bought was standard granular activated carbon - and almost every Australian capital except Hobart and Canberra uses chloramine instead of free chlorine for disinfection. Brisbane, Sydney, Adelaide, Perth, Darwin all chloramine. Melbourne is split - depends which retailer supplies your suburb. Standard carbon doesn't touch chloramine. So somewhere around 5 million Australians are running Brita-style filters that aren't doing what they think they're doing.

The other thing nobody mentions: fluoride and PFAS only come out via reverse osmosis. No carbon filter of any kind removes them, regardless of what the marketing says. Sydney has the highest fluoride of any capital at 1.0 mg/L. PFAS hotspots are mostly defence-base adjacent - Williamtown is the famous one with the $212m class action, but Oakey, Katherine, RAAF Edinburgh and RAAF Pearce all have documented contamination too.

Adelaide is its own situation. Water comes off the Murray, TDS hits ~480 mg/L (highest of any capital), sodium ~66 mg/L. Worth knowing if anyone in the house has hypertension or is on dialysis.

The cost angle was the bit that actually changed how I thought about it. An under-sink RO including five years of cartridge replacements works out to about $1,400 all up. Bottled water at 4L a day for the same five years is around $8,800. If you're already a bottled water household it pays itself off inside two years, and the filter output is measurably cleaner - RO under 10 ppm vs bottled water sitting anywhere between 5 and 50 depending on the brand.

I ended up putting all of this into a little decision tool so I'd never have to redo the research. Free, no signup, asks a few questions and tells you what fits your city. Happy to drop the link if anyone wants it, otherwise I've got the data here and can answer specific city questions in the thread.

The thing I wish I'd known before spending $200 on the wrong filter: just check whether your city uses chloramine or chlorine first. That one question narrows the whole decision down to two paths instead of fifty.

We moved into a place on the Gold Coast last year and the tap water tasted off, so I grabbed one of those benchtop filter jugs from Bunnings.

Felt better drinking it for a few months. Then I bought a $15 TDS meter to see how well the thing was actually working and the reading was basically identical to straight tap. 370 before, 360 after. I'd spent two hundred bucks on a placebo.

Went down a rabbit hole after that. Turns out the filter I bought was standard granular activated carbon - and almost every Australian capital except Hobart and Canberra uses chloramine instead of free chlorine for disinfection. Brisbane, Sydney, Adelaide, Perth, Darwin all chloramine. Melbourne is split - depends which retailer supplies your suburb. Standard carbon doesn't touch chloramine. So somewhere around 5 million Australians are running Brita-style filters that aren't doing what they think they're doing.

The other thing nobody mentions: fluoride and PFAS only come out via reverse osmosis. No carbon filter of any kind removes them, regardless of what the marketing says. Sydney has the highest fluoride of any capital at 1.0 mg/L. PFAS hotspots are mostly defence-base adjacent - Williamtown is the famous one with the $212m class action, but Oakey, Katherine, RAAF Edinburgh and RAAF Pearce all have documented contamination too.

Adelaide is its own situation. Water comes off the Murray, TDS hits ~480 mg/L (highest of any capital), sodium ~66 mg/L. Worth knowing if anyone in the house has hypertension or is on dialysis.

The cost angle was the bit that actually changed how I thought about it. An under-sink RO including five years of cartridge replacements works out to about $1,400 all up. Bottled water at 4L a day for the same five years is around $8,800. If you're already a bottled water household it pays itself off inside two years, and the filter output is measurably cleaner - RO under 10 ppm vs bottled water sitting anywhere between 5 and 50 depending on the brand.

I ended up putting all of this into a little decision tool so I'd never have to redo the research. Free, no signup, asks a few questions and tells you what fits your city. Happy to drop the link if anyone wants it, otherwise I've got the data here and can answer specific city questions in the thread.

The thing I wish I'd known before spending $200 on the wrong filter: just check whether your city uses chloramine or chlorine first. That one question narrows the whole decision down to two paths instead of fifty.