Whole house water filter

Forums › Home Workshop DIY › Whole house water filter - for e coli

kingdragonfly

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#324714 17-May-2026 10:34

I live near dairy farms, and we've had a couple of temporary "boil-water" scares due to e coli contamination scares, and lost confidence in the council water.

I already have an under sink filter, but I need to cover two kitchens, and it must have UV light protection to kill e coli.

I'm interested in whole house water cleaners, one with a UV light to kill e coli; the kind for people off the grid, who depend on rain water collected from a roof (with bird poop contamination)

Anyone done business with NZ Filter Warehouse in Manukau Auckland NZ?

Extra thanks if you know anything about Alpine Pure Bug diamond at $1,050

The replaceable 3 large filters + UV lamp replacement can start at $464, and the quartz sleeve has to be replaced when damaged/clouded, about every 3 years at $100

PL05MP2 Cartridge
CB05MP2 Cartridge
PX01MP2 Cartridge

It looks very similar to a Mitre 10 - Puretec Hybrid R11 Triple Water Treatment currently at $3,049.

For future surfers, wanting long term costs the UV light uses about $110 in electricity per year. Again for future surfers my research indicates it's only partially filters agricultural chemicals / pesticides, Manganese not really, and won't filter nitrates at all.

My question is about experience with NZ Filter Warehouse, as mentioned.

Cheers

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#3491807 17-May-2026 12:06

Purtec is very good but very expensive, not sure about the Alpine - looks like a good price though I'd be tempted.

Will probably need a pressure reducing value on the mains before the unit (if you don't already have one) to ensure your water pressure is below 500kpa.

kingdragonfly

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#3491808 17-May-2026 12:26

Ragnor:
Purtec is very good but very expensive, not sure about the Alpine - looks like a good price though I'd be tempted.

Will probably need a pressure reducing value on the mains before the unit (if you don't already have one) to ensure your water pressure is below 500kpa.

hmm... you're right. if pressure is too high, UV light can't keep up.

mentalinc

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#3491861 17-May-2026 13:02

Only ever ordered normal under bench filters from nzfilterwarehouse and always been delivered quickly, and helpful when needing to confirm filters.

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aaristotle

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#3491868 17-May-2026 14:09

I've had one of these systems from NZ Filter warehouse https://www.nzfilterwarehouse.com/product/bug-buster-silver-pro-series for 8 years.

I replace the UV lamp yearly with the generic lamp they recommend rather than the Viqua OEM lamp which is more expensive. I am pumping out of a well into a tank then through the filter, so what little sediment there is settles and the filters last 2-3 years. You can tell when the filters need replacing by the difference in the 2 pressure gauges .The glass tube has never needed replacing as it is still perfectly clear, but I assume this depends on the water mineral content.

Before the filter was installed our water test came back with high ecoli levels, but after installation every test has zero ecoli.

I would probably skip the 3rd carbon filter on the system you are looking at, unless you are wanting to remove chlorine from a town water supply. If this is the case it might be cheaper to just carbon filter the under sink water fountain.

I've also replaced the UV ballast this year as it was overheating. Apparently they only last 5-7 years so it didn't do to badly.

davidcole

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#3491871 17-May-2026 15:12

I have the puretec wh2-60. 60 refers to the upper flow rate. I think for ecoli and tank systems you need the ultraviolet as well. Mine is just the carbon plus sediment filters. On lower hutt town water I chew through those in 6 months. Before you start tasting chlorine agin. And the sediment filter is very dark.

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tweake

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#3491922 17-May-2026 16:07

kingdragonfly: I live near dairy farms, and we've had a couple of temporary "boil-water" scares due to e coli contamination scares, and lost confidence in the council water.

I already have an under sink filter, but I need to cover two kitchens, and it must have UV light protection to kill e coli.

I'm interested in whole house water cleaners, one with a UV light to kill e coli; the kind for people off the grid, who depend on rain water collected from a roof (with bird poop contamination)

Anyone done business with NZ Filter Warehouse in Manukau Auckland NZ?

Extra thanks if you know anything about Alpine Pure Bug diamond at $1,050

The replaceable 3 large filters + UV lamp replacement can start at $464, and the quartz sleeve has to be replaced when damaged/clouded, about every 3 years at $100

PL05MP2 Cartridge
CB05MP2 Cartridge
PX01MP2 Cartridge
It looks very similar to a Mitre 10 - Puretec Hybrid R11 Triple Water Treatment currently at $3,049.

For future surfers, wanting long term costs the UV light uses about $110 in electricity per year. Again for future surfers my research indicates it's only partially filters agricultural chemicals / pesticides, Manganese not really, and won't filter nitrates at all.

My question is about experience with NZ Filter Warehouse, as mentioned.

Cheers

i've had no problem with nz filter warehouse. i got my last lot of filters through them.

i run filters on the mains at home, but also do the work setup as it requires food grade water system from the tanks, and it gets tested every year.

the basics is use a course filter for large bits, eg 50mic or 20mic. if its really dirty a flushable mesh prefilter is recommended. then finer filter, typically a 5mic or a 1mic. then carbon if you want to get rid of chlorine, a bigger mic rating than your finest filter. eg 5 mic carbon needs a 1 mic filter before it.

uv, size is down to flow requirements. one small downsize is they heat the water up when the water is not being used for a long time. not usually a problem in most houses. some manufactures have timers which force you to replace the ballast ever so many years. your meant to change bulb every so often and they have a counter for that. however if its oversized you can go years without changing bulbs. the quartz never really needs changing especially on tank water. ours is 20 years old or so.

uv has nothing to do with pressure. as long as the unit is rated for the pressure so it doesn't break. flow rates is what determines effectiveness, which is dictated by length of the unit. higher flow rate needs longer bulb.

most of the good filter housings will handle most main water pressures. but check first as some cheaper ones are lower pressure rated. i have a pressure regulator AFTER the water filters, that way the pressure drop across the filters doesn't affect pressures at the tap until filter is clogged.

pesticides etc require a different type of filter eg resin type etc. i think there is a few different systems, something i never needed to look at.

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tweake

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#3491923 17-May-2026 16:12

davidcole:

I have the puretec wh2-60. 60 refers to the upper flow rate. I think for ecoli and tank systems you need the ultraviolet as well. Mine is just the carbon plus sediment filters. On lower hutt town water I chew through those in 6 months. Before you start tasting chlorine agin. And the sediment filter is very dark.

i have had similar issues.

what mic rating carbon and filters are you using?

davidcole

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#3491925 17-May-2026 16:34

tweake:

davidcole:

I have the puretec wh2-60. 60 refers to the upper flow rate. I think for ecoli and tank systems you need the ultraviolet as well. Mine is just the carbon plus sediment filters. On lower hutt town water I chew through those in 6 months. Before you start tasting chlorine agin. And the sediment filter is very dark.

i have had similar issues.

what mic rating carbon and filters are you using?

5 for sediment and 10 from carbon I think.

I hear I’m quite close to the lower hutt bore so that is the suspicion why it’s so dirty.

tweake

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#3492026 17-May-2026 17:05

davidcole:

5 for sediment and 10 from carbon I think.

I hear I’m quite close to the lower hutt bore so that is the suspicion why it’s so dirty.

the dirt level is down to the plant filter system. we just got an upgrade done here so now its cleaner which allows them to use less chlorine.

i would use a 5mic carbon. its a little bit more expensive, $10 more, but it lasts a lot longer. but you would need a 1 mic filter. i ended up with one of the pleated washable 1 mics. just rinse it out every 6 months. you can go finer carbon again, 1mic, but filters get expensive quick as you need submicron. the other tradeoff is flow rate.

Yetti92

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#3493233 18-May-2026 09:46

If you have an E. coli issue, the only way to treat it will be UV or RO (Reverse osmosis). If nitrates are an issue, they are hard to remove unless you use an RO unit; council water supplies must test for these, but the limit is quite high at 11 ppm in NZ.

The cartridge filters are critical for getting the particulates out of the water for the UV unit, as UV Transmittance (UVT) is affected by particulates and can create issues for the UV light transmission, which kills the ecoli. Systems generally use a 20 or 10micro filter first, which then flows into a 1 or 0.5 micro filter. This also takes out any cysts, such as Giardia and Cryptosporidium, as in the past, some councils have lacked filtration for these parasites, such as the outbreak in Queenstown a while back that can't be treated with just UV. If you are worried about taste and/or chlorine, then add a carbon filter to the cartridge filter. But yes, 1 micron can decrease water pressure a little, but this may increase exposure time for the water in the UV tube. As you mentioned, you were on a council supply; they may already be filtering, which may reduce your need to regularly change particulate filters if the water is nice and clear. You could ask the council to provide you with a water analysis, as they are required now to regularly test at accredited labs and report back to the government. Look for the turbidity rating, as this will give you some idea of how clear your water is and how often you may need to replace cartridge filters and what you might need for your area specifically.

For reference, the NZ water regulator Taumata Arowai has some approved/acceptable treatment systems for drinking water suppliers on a small scale for homes, which now can include anyone who supplies water to another property in most cases. They cite UV and cartridges as an acceptable water treatment system, with some technical details that might help.

https://www.taumataarowai.govt.nz/drinking-water-suppliers-and-operators/for-drinking-water-suppliers/ways-to-comply/acceptable-solutions

kingdragonfly

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#3493236 18-May-2026 09:51

@Yetti92 That was very helpful. Cheers

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MikeAqua

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#3493290 18-May-2026 11:43

kingdragonfly:

hmm... you're right. if pressure is too high, UV light can't keep up.

Pressure isn't inherently limiting for UV filters - unless it's so high you have physical failure. Flow rate and water clarity can be very limiting.

It's been a while since I was down the rabbit hole of UV filters, but ... the UV dose required to kill pathogen used to be expressed as the amount of UV energy that hits each unit of its surface (e.g. cell wall).

Two things effect this:

How long the water spends passing through the UV filter - faster flow reduce the amount of UV each pathogen is exposed too. And,
How clear the water is - more turbid water partially shades pathogens, reducing the amount of UV each is exposed to.

The second one is hard to visualise, until you understand how small some these pathogens are. For viruses your usually down to the nanometer scale.

Any reputable manufacture of a UV filter should provide a dose vs flow rate graph. There will be specific dose rate for treating drinking water. Remember E.coli is an indicator organism. Other pathogens that cooccur with it are the real concern. (exception for pathogenic strains of ecoli)

Another factor is how long the UV filter takes to warm up (generally quick for LEDs). I let the UV lamp run for few seconds after water flow stops. That way the water that is in the UV tube when flow starts again is already treated. In a critical system (e.g. incoming water for bio-secure facilities), I'd run 30 seconds of water to waste (or back to the untreated water). That would be OTT for a domestic installation.

UV filters last a long time if you prefilter your water sufficiently and clean them regularly and carefully. I'd have the UV filter as the last filter (after carbon). I also found some little electronic hour meters which could track how many hours each tube had done. This allowed cleaning and replacement to be programmed.

I noticed you also referred to removing nitrates. That's difficult. They're a small, dissolved molecule. You're basically talking about laboratory water systems - distillation, RO or similar. Nitrates aren't usually a threat to healthy adults. If you have infants (or other vulnerable people) in the household, I'd look at bottled water for drinking to avoiding nitrates (assuming levels are actaully high in you two supply). Boiling won't remove nitrates. It will concentrate them slightly, because when you boil water some of it escapes as steam.

Mike

tweake

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#3493494 18-May-2026 17:56

Yetti92:

As you mentioned, you were on a council supply; they may already be filtering, which may reduce your need to regularly change particulate filters if the water is nice and clear.

https://www.taumataarowai.govt.nz/drinking-water-suppliers-and-operators/for-drinking-water-suppliers/ways-to-comply/acceptable-solutions

don't count on the town water supply being clean even if they are filtering. i was very surprised at how dirty ours was here, it was way worse than rural tank water.

thx for the link thats helpful.

tweake

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#3493495 18-May-2026 17:59

MikeAqua:

Another factor is how long the UV filter takes to warm up (generally quick for LEDs). I let the UV lamp run for few seconds after water flow stops. That way the water that is in the UV tube when flow starts again is already treated. In a critical system (e.g. incoming water for bio-secure facilities), I'd run 30 seconds of water to waste (or back to the untreated water). That would be OTT for a domestic installation.

UV filters last a long time if you prefilter your water sufficiently and clean them regularly and carefully. I'd have the UV filter as the last filter (after carbon). I also found some little electronic hour meters which could track how many hours each tube had done. This allowed cleaning and replacement to be programmed.

all the UV systems i've dealt with all run the UV constantly, hence you get a bit of hot water in it if you go away for the weekend. the controller also has built in hour meter as you are meant to replace the lamp after so many hours of use.

Paul1977

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#3493709 19-May-2026 10:52

We got ours here: Household Filter Systems | Water Filtration System for Home. We got a 3 stage jumbo 20". We didn't do UV on ours as we're in the suburbs and didn't think we'd need it, but they have plenty of options.

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