How to choose a shower filter in New Zealand
Compare the filter media, flow, cartridge life, fit and test evidence, then see what a year of cartridges costs in NZ dollars.
How this guide was written
Written by SUHAE
SUHAE sells shower filters, and this guide says so up front. Every claim about our own product links to the lab report behind it. About SUHAE.
Comparisons by filter type
The comparisons describe common filter types. Where we name our own result, we name the lab too.
What does a shower filter actually do?
A shower filter takes chlorine out of the water at the shower head and, depending on its media, catches sediment and rust from the pipes on the way.
Why chlorine is the job in New Zealand
Your water arrives with a little free chlorine in it, put there on purpose so it stays safe to the end of the pipe network. A shower filter deals with that chlorine in the last two metres between the wall and you.
New Zealand town water is mostly soft, so scale is rarely the issue. Chlorine is in every town supply, which is why it is the thing worth filtering.
For drinking water, use a filter made for the kitchen tap.
What should you compare in a shower filter?
Compare the filter media, the measured flow rate, cartridge life, fit, and whether it adds a scent.
Three stages, drawn to scale. A body of media, a thin layer, and a washer.
The media, and how it works
The number of stages tells you less than what is inside them. Check the material, the quantity, the order and the published test result for each stage.
Adsorption, chemical reduction, and which is which
Adsorption holds chlorine on a surface. Activated carbon is the common one: it works on free chlorine, it needs contact time, and it eventually fills up.
Chemical reduction converts the chlorine instead, and the media is used up rather than filled. Calcium sulfite, copper-zinc redox media and ascorbic acid all work this way.
In a shower the water moves fast, so media that reacts as the water passes has an easier job than media that needs the water to linger. The longer explanation is here, and what is inside ours is here.
Flow rate
Flow rate affects shower feel and the time water spends in contact with the filter media. Compare figures measured on the complete installed product.
5.0 litres a minute, tested to AS/NZS 3662:2013, the Australian and New Zealand Standard, by Singapore Laboratory Services rather than by the manufacturer. How the plate does it.
Why less water is not less filtration
A head that moves less water gives the media longer to work, not less. Each drop spends proportionally longer in it.
When a brand claims higher pressure, check whether the figure comes from an independent report, manufacturer testing or an unmeasured description.
Cartridge life
Cartridge life depends on how much water your household uses. Look for a tested litre figure, or a monthly estimate that says what it assumes.
Fittings
New Zealand showers use a standard ½-inch thread. Check the space you have, the weight of the filter, and whether your shower is fixed, handheld or overhead.
Whether it adds anything
Some cartridges add a scent. Choose it on purpose, and check there is an unscented option if you want one.
What does a chlorine removal percentage actually mean?
A removal figure tells you most when the test names the product, the lab, the method and how many litres it ran for.
Both can be reported as a percentage. A beaker gives the media close to a minute. A shower head gives it a fraction of a second. A result measured over thousands of litres of flowing water tells you more. Our result, and how it was measured.
Look for four things next to any figure.
- The flow rate it was measured at, in litres per minute, written L/min.
- The water temperature.
- How many litres it ran for, not just a reading off a fresh cartridge.
- Who ran the test, by name.
Hold every brand, ours included, to the same four.
What is NSF/ANSI 177?
An American standard for shower filters. It covers the reduction of free chlorine.
Check certification at product level
Search the certifier's public database for the exact product model. A certificate for one product does not cover another from the same brand.
A named lab and a certificate number
Whatever the standard, the useful part is a lab you can name and a number you can look up. Our chlorine result is KEWI certificate IW-230133.
And read the wording around it
Certification means an independent body has tested the product against a written protocol and continues to audit it, which is more than an in-house test.
A brand can hold a certificate on a drinking water product and describe itself as certified. Ask which standard, which product and which certifying body.
How much does a shower filter cost to run per year?
Annual running cost is the cartridge price times the number of cartridges your household uses in a year.
Numbers stay in your browser. The default values are our own Vita Refill in NZ dollars, so the first number you see is ours.
Two things worth checking
When cartridge life is given as a range, use the shorter end for a careful estimate.
If a subscription is offered, check how often it ships and how you skip or stop it.
Look at the unit price and the cartridge price together. A cheap unit with expensive cartridges costs more by the second year.
Is my water hard, or is it chlorine I am noticing?
In most of New Zealand it is chlorine. Hardness and chlorine are separate things, and your supplier publishes both.
Where hardness fits in New Zealand
Hardness comes from dissolved calcium and magnesium and shows up as white marks on glass. Christchurch publishes 45 mg/L and Wellington's plants run 18 to 45, both soft, under New Zealand's 100 mg/L line. Some Auckland sources are moderately hard.
Every New Zealand town supply is disinfected with free chlorine, and a vitamin C shower filter is built to take that chlorine out at the shower head.
City by city, with each supplier's figures and sources: the NZ Water Guide.
How long does a shower filter cartridge last?
It depends on how much your household showers. Most brands give a time estimate, and the better ones give a tested litre figure too.
- Note the date you installed it.
- Note the date you noticed a change.
- The gap is your household's real cartridge life, and it beats anything on the box.
Why the published figures vary so much
Use the maker's replacement interval as your guide, and change a little earlier in a busy household. A tested litre figure is the clearest way to compare. Ours: chlorine not detected through 6,000 litres.
Will it fit a New Zealand shower?
New Zealand showers use a standard ½-inch thread. What matters next is the space you have and whether your shower is fixed, handheld or overhead.
Measure the clearance below your shower arm before you order. The filter adds length in line with the fitting.
Check the weight and cradle angle
An attachment can add weight or length near a handheld cradle. Check the available clearance and whether the head stays at your preferred angle.
Renting or flatting?
There is more on install and moving out on the renters page.
What should I ask before I buy?
Eight questions that cover the evidence, fit, running cost and support. They work on any brand, ours included.
- What is the media made of? Not how many stages. What each one contains.
- At what flow rate and temperature was the removal figure measured? If it is not on the page, ask for it.
- Who ran the test? A named laboratory, or an in-house claim.
- Is the result measured over a cartridge's life? One reading off a fresh cartridge tells you less than six across it.
- Is the cartridge life one number or a range? Litres is the clearest unit.
- What does a year of cartridges cost? The calculator above takes ten seconds, in NZ dollars.
- Does it add anything to the water? Minerals or fragrance.
- What happens if it does not work for me? Returns window, postage, and whether a used cartridge counts against you.
8. What warranty applies?
SUHAE gives a lifetime warranty on eligible shower hardware. Read the full warranty and delivery terms before ordering.
For fit questions, send us a photo on WhatsApp before you order.
Is a shower filter worth it?
Start with what you notice in your shower
If your shower smells of chlorine, a filter that takes chlorine out changes something you can notice on the first day.
Make the change measurable
A free-chlorine test strip before and after fitting gives you your own answer, in your own bathroom.
How to read a performance claim
Check that a percentage names the product, the lab, the method and the litres it ran for.
New Zealand town water is soft in most cities and chlorinated in all of them, so choose a filter for what it does to chlorine.
Compare SUHAE using the same eight questions
Our test conditions, fit, cartridge life, running cost in NZ dollars and warranty, all on the page before you choose.