Rainwater Filters and Tank Water Treatment
Safe rainwater from the roof to the tap.
Book a FREE onsite visit.
Is your tank water safe to drink?
Rainwater looks clean, but by the time it reaches your tank it has run over your roof and through your gutters. It picks up bird and possum droppings, leaves, dust and anything else up there, and bugs like E. coli, Campylobacter and Giardia can come with it. Clear water can still make you sick.
Good tank water starts on the roof: clean gutters, a first flush diverter and a tank that’s sealed and looked after. Then, where the water comes into the house, sediment filters take out the dirt and a UV system kills the bugs, so every tap is safe to drink.
In our view, every home on tank water should have a UV system with sediment filters. We’ve installed and serviced them across Rodney and North Auckland since 2000, from Mangawhai to Albany.
Start with a free onsite visit.
From the roof to the tap
Every part of a rainwater system affects the water you drink. Tap a step to find out more.
Roof, gutters and first flush
Clean gutters, leaf guards and a first flush diverter keep the worst off the roof out of your tank.
Your water tank
A sealed tank with a Maelstrom pre-tank filter, a calmed inlet and a floating outlet.
Ozone in the tank
Treats the water in the tank itself, and is brilliant at getting rid of smells.
Pump and pressure
The right pump gives steady pressure at every tap, and enough flow for your treatment system.
Filters and UV
Sediment filters take out the dirt where the water comes into the house, then UV kills the bugs.
Tank level indicators
Check your water level from your phone, and spot a problem before you run out.
Featured Product
Aqua Jumbo High-Capacity UV Water Filter
A high-capacity, 3-stage UV water filter system for clean, safe drinking water at home. It suits homes with 3 to 5 bathrooms and light commercial use, on rainwater, bore or surface water. Not sure if it's the right fit? Call us and talk to our water filtration experts.
$1,645.00 excl. GST
Which tank water system suits your home?
All our Aqua UV systems come fully assembled on a stainless steel bracket, with twin sediment filters in front of the UV lamp and a stainless cover to keep the weather off. We match the size to your home and your pump.
- Aqua Jumbo: our most popular. Twin 20-inch filters, for homes with 3 to 5 bathrooms, lifestyle blocks and gravity-fed supplies.
- Aqua BIG: twin 10-inch filters (20 and 1 micron), for homes with 1 or 2 bathrooms.
- Aqua Mini: for tiny houses.
Water tastes or smells? We can add a carbon filter, or treat the tank itself with ozone, which is brilliant at getting rid of smells.
Why tank water needs treatment
Most of the contamination in tank water comes from the roof, the gutters and the tank, not the rain. Birds, possums and rats leave droppings, dead animals and insects end up in gutters and tanks, leaves rot, and dust and ash wash in. The first water off the roof is the dirtiest.
It’s common, too. In a study of 125 rural Auckland homes on roof water, more than half the samples showed faecal contamination.
The bugs in that water are what make people sick. Babies, older people and anyone with a weakened immune system are most at risk. You can’t see, smell or taste them, so clear water isn’t proof that it’s safe.
What a tank water system does
It works in layers. Clean gutters, a first flush diverter and a pre-tank filter keep the worst out of the tank. Sediment filters take out the dirt where the water comes into the house. A UV system then kills the bugs that make people sick, with no chemicals added. If the water tastes or smells, a carbon filter or ozone in the tank deals with that.
Rainwater and copper pipes
Rainwater is soft and often slightly acidic, around pH 6. Water like that can dissolve copper from pipes and fittings, leaving blue-green stains in basins and showers, and we’ve seen it lead to pinhole leaks in copper pipe. It can also pick up lead from old roof flashings or lead-based paint. If you’re seeing blue-green staining, call us: we can test the water and fit a pH neutraliser.
Signs your tank water needs attention
Someone in the house has been sick.
Cloudy or discoloured water.
Bits or sediment in the water.
An earthy or musty taste or smell.
Blue-green stains on basins or showers.
Low water pressure. Often the filters are blocked.
Running out of water early. Blocked gutters or downpipes mean you’re not collecting all the rain.
No UV system, or a UV lamp older than a year.
You don’t know when the tank was last cleaned.
What treatment does
- Kills bacteria, viruses and parasites like E. coli and Giardia.
- Takes out sediment, dirt and particles.
- Treats every tap in the house, not just the kitchen.
- Carbon or ozone can fix a bad taste or smell.
What it doesn’t do
- Remove metals like copper or lead, or chemicals, without the right filters.
- Correct acidic water. That needs a pH neutraliser.
- Keep working without a service every year.
- Fix a dirty tank or blocked gutters.
Safe water from every tap, without boiling the jug.
Local Jobs – Local Trust – Local Experts
Recent tank water jobs
A few of the rainwater systems we’ve installed and look after.
Marram Place, Mangawhai Heads: a new home on tank water. We installed the tank, the pump and suction line, and a whole house Aqua UV system, and connected the downpipes to the tank and its overflow.
Inside the box: the Aqua UV system with twin sediment filters and the water pump, all out of the weather.
Kaipara Flats: a Viqua UV system and twin filters on one of our stainless brackets, with a Grundfos pump on its own base.
Look after the tank, too
Treatment at the house only works well if the tank is in good shape. Sludge builds up on the bottom of every tank over time. A Maelstrom pre-tank filter screens the water down to 180 microns before it goes in, and cleans itself. A calmed inlet stops new water stirring up the sludge, and a floating outlet draws the cleaner water from just below the surface.
The Ministry of Health tank guide recommends a calmed inlet, a floating outlet and insect screens on the overflow. Clean the gutters every three months and after storms, check the tank every year, and have the sludge cleaned out when it builds up, or straight away if the water turns cloudy, coloured or smelly. Don’t collect drinking water from roofs with lead flashings, lead-based paint or treated timber shingles. Our water tank installation team can fit a Maelstrom filter, a calmed inlet and a floating outlet to an existing tank.
Test your water
A water test tells you what’s really in your tank. An E. coli test shows whether droppings or other contamination have got in. A chemical test picks up metals like lead and copper.
For peace of mind, the household water supplies guide (ESR, 2021 update) suggests a lab test for bugs every three months and a chemical test every year. It also suggests testing when the system is new or changed, after heavy rain, and if someone in the house is pregnant or there are young children.
We can take the sample and send it to an accredited lab. Renting out or selling? See safe water for rural rentals and sales.
How we sort your tank water
Every job follows the same four steps.
1
Free onsite visit
We look over the whole system: roof, gutters, tank, pump and any treatment you already have.
2
Find what’s wrong
We work out what’s causing the problem and tell you what needs improving, and why.
3
Install and upgrade
Our registered plumbers fix or upgrade whatever needs it, then sterilise the pipes so the house starts clean.
4
Service every year
New filters, a new UV lamp if you have one, a check of the whole system, and a reminder when it’s due.
Professional installation
Our own registered plumbers install tank water systems across Rodney and North Auckland, from Mangawhai to Albany.
- Sized to your home, your pump and how much water you use.
- Fitted where the water enters the house, so every tap is treated.
- Pipes sterilised after the install.
- Covered outside to keep the sun and rain off.
Ongoing service and support
Every tank water system needs a service every 12 months. We fit new filters, replace the UV lamp and clean its sleeve if you have one, and check the pump, tank and gutters while we’re there. UV lamps are rated for about 9,000 hours, roughly a year, so the yearly change matters. We remind you when it’s due, and we service most makes and models: see UV water filter servicing.
Tank water FAQs
Is tank water safe to drink?
What is the best water filter for tank water?
For most homes, twin sediment filters followed by a UV system. The filters take out the dirt and the UV kills the bugs. If the water tastes or smells, a carbon filter or ozone in the tank helps. A filter on its own, without UV, doesn’t make tank water safe to drink.
How often should I change my tank water filters?
Every 12 months at your yearly service, or sooner if the water is dirty and the pressure drops. We remind you when your service is due.
Do I still need to boil my tank water?
Not if you have a working UV system with good filters that is serviced every year. Without treatment, boil your drinking water: a rolling boil for one minute. If the power goes off or the UV alarm sounds, boil it until the system is working again.
How often should I clean my water tank?
Check the tank every year and have the sludge cleaned out when it builds up, or straight away if the water turns cloudy, coloured or smelly. A calmed inlet and a floating outlet help keep the sludge where it belongs.
Do I need a first flush diverter?
We recommend one. It sends the first, dirtiest water off the roof away from the tank, along with most of the droppings and dust. BRANZ suggests diverting about 20 to 50 litres for every 100 square metres of roof. Read more about rainwater harvesting.
Why do I keep running out of tank water?
Often the gutters or downpipes are blocked, so you’re not collecting all the rain your roof could. A leak, or a tank that’s too small for the household, can also be the cause. A tank level indicator shows you what’s happening, and we can check the whole system.
Can ozone fix smelly tank water?
Often, yes. Ozone treats the water in the tank itself and is brilliant at getting rid of smells. See ozone tank treatment.
Why is my tank water cloudy or smelly?
Usually sediment stirred up from the bottom of the tank, rotting leaves, or something that has got into the tank. It can also mean the filters are overdue. We can check the tank and the system and tell you what’s going on.
Can rainwater damage my pipes?
It can. Rainwater is soft and often slightly acidic, so it can dissolve copper from pipes and fittings and leave blue-green stains. If you see blue-green staining, call us and we can test the water and fit a pH neutraliser.
How much does tank water treatment cost?
You’ll find current prices for our Aqua UV systems in our online shop. Installation depends on your site and pump, so we quote after a free onsite visit.
Don’t just take our word for it…
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“We have an advanced rain water treatment system at our Mangawhai Heads home which includes whole house neutralisation, UV treatment and 3-stage filtration with KDF/GAC, primarily for removal of copper contamination from gutters and down pipes. The system was supplied and installed by Aqua Works and has just had its first annual service by them. We have been totally satisfied with the expert service throughout …”
Richard Mules, 2025
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“Steve and team from Aqua Works did a great job installing a UV filter system, upgraded larger pump and a very tidy cement job to secure tank pipes that were loose and leaking. Great communication, easy to work with and I am thrilled with the professionalism. …”
Shaye Chirotarrab, 2026
⭐⭐⭐⭐⭐
“Thank you, Rich, from Aquaworks Having never lived on tank water, Rich was informative about our system and how it works We intend to use you in the future …”
H R Fairclough, 2024
Want safe tank water at every tap?
Book a FREE onsite visit. We’ll check your system from the roof to the tap and tell you what it needs.