28 May 2026

Should New Zealand be more proactive in collecting rainwater?

Yes. New Zealand should be more proactive about collecting rainwater because rainfall patterns are changing, water demand and supply pressure remain real issues, and rainwater harvesting can improve resilience, reduce reliance on mains supply, and support better water security for homes, farms, and businesses. In 2026, the strongest case for rainwater collection is not just sustainability - it is preparedness, flexibility, and smarter use of an available resource.

Rainwater harvesting has moved beyond being a niche environmental choice. In 2026, it is a practical water management strategy that can help New Zealanders reduce pressure on local networks, improve resilience during dry periods, and make better use of the rainfall that already falls on roofs across the country.

For many properties, the biggest opportunity is not whether rainwater can be collected. It is whether it is being collected efficiently, stored well, and monitored properly. That is where smart water tank level indicators become especially relevant, because they turn water storage from guesswork into usable data.

Back in August 2020, Stuff questioned the traction of rainwater tanks in New Zealand. At the time, a survey of 66 territorial authorities revealed a mixed bag of support. While some councils like Kapiti and Gore led the way with incentives and requirements for rainwater harvesting, many remained neutral.

Fast forward to 2026, and the situation demands a more urgent and proactive approach. 

Why rainwater matters now

Rainfall across Aotearoa is not static. Stats NZ reports that annual rainfall likely or very likely increased at 15 of 30 sites and decreased at 8 of 30 sites between 1960 and 2022, which shows that local rainfall patterns are shifting rather than staying predictable. That matters because water planning based on old assumptions is less reliable than it used to be.

At the same time, rainwater is already an important source for many people. According to Level, approximately 10 percent of New Zealand’s population depends on roof-collected rainwater for drinking water. That figure shows rainwater is not an experimental idea in New Zealand. It is already part of the country’s water reality.

The case for collecting more rainwater is therefore not just about personal preference. It is about using a resource that falls naturally, can be stored for later use, and can reduce pressure on supply systems during dry or high-demand periods.

The Climate Has Changed: Droughts and Dam Levels

Since 2020, water restrictions have become commonplace, particularly in Auckland. The severe drought of 2019-20 saw dam levels plummet to critical lows, leading to strict water usage rules. While Auckland's dam levels have recovered somewhat, they are once again below average, and the risk of future droughts remains a significant concern for residential, commercial and agricultural water users.

The cost of supplementing water supplies, like drawing from the Waikato River, is substantial and will impact water bills for years. It's time to future-proof our water supply by embracing rainwater harvesting on a larger scale.


In April 2025, we reported that Auckland was once again reliant on drawing water from the Waikato River. Up until the end of March last year, Auckland was drawing approximately 40% of its water supply from the Waikato River, with 60% coming from dams.

As we head into winter this year, it's a slightly different picture with Auckland dams already tracking at nearly 95% capacity, although this doesn't mean we should rest on our laurels.

Homes and businesses should be planning ahead and thinking about how they can combat potential water restrictions now. Installing a water tank as we head into winter is the perfect time as you will benefit from storing up the water that you can collect over the wetter months before we reach the drier conditions of the summer.

Future-Proofing with Rainwater Harvesting

The concept of future-proofing is key, especially for new build properties. Integrating rainwater harvesting systems from the outset is far more efficient and cost-effective than retrofitting later. However, retrofitting existing homes is also a viable and increasingly necessary option.

Slimline Tanks: A Practical Solution

One of the barriers to rainwater harvesting has been the perception of bulky, unsightly tanks. Fortunately, advancements in tank design have led to the rise of slimline water tanks. These tanks are more practical for many households, fitting neatly against fences or along the sides of buildings, maximising space while still capturing valuable rainwater. These tanks also often fit in with updates to the resource consent programme, meaning they often don’t require consent to install.


Policy Changes and Incentives

Auckland Council has taken steps to encourage rainwater harvesting, including removing resource consent fees for residential installations. However, more widespread policy changes and incentives are needed across the country to make rainwater harvesting a standard practice.

In further changes to the Auckland Unitary Plan and Hauraki Gulf Islands District Plan, rainwater harvesting became even more accessible with updates to the plan meaning that in most residential zones, you may not need resource consent if:

  • your tank is placed at least 10m away from a stream, 30m away from a lake or 10m away from the coastline
  • the tank is not placed between the front of the building and the street
  • your tank is not higher than 3m if placed in a side or rear yard
  • your tank is installed completely below ground level when sited in a designated ‘outdoor living space’ area
  • your tank is no higher than 1m when sited in a required ‘outlook’ area
  • your tank overflow drains to the existing onsite stormwater discharge point (where the stormwater ran before your rainwater tank was connected)
  • your tank overflow does not flow across an effluent dispersal area

You should still always check before you start a project, however, these are at least steps in the right direction towards encouraging more people to invest in water tanks for rainwater harvesting.

Calculating Your Harvestable Water

There are several different calculations that people use to work out how much water can be captured and stored but we like this model:

1.       Estimate the size of your roof by calculating the length x width of your property. You can also visit websites like homes.co.nz where you can find out the overall size of your property and use this as a guide i.e., 170m²

2.       Look up the annual rainfall for your area. Head over to the NIWA website where you will find that information.

Once you know these two bits of information, then it’s a simple equation to calculate your harvestable water potential:

Litres per square metre of catchment x catchment area (roof area) = litres of harvestable water

You can calculate the litres per square metre of catchment based on the annual rainfall for your area. The annual rainfall for your area in mm is equal to the litres per square metre of catchment.

Example:

The average rainfall in Auckland is 1,114mm per year. My property is 172m².

1,114 litres x 172m² = 191,608 of harvestable water per year

You can read more about rain collection and the size of water tank you might need in our recent post, What size water tank do I need?

Why many sites still underuse rainwater

One of the biggest barriers is not technology. It's planning. Many properties do not collect rainwater because they have not worked out the right tank size, how much roof area is available, or what the water will be used for. That means the issue is often not willingness, but clarity.

Another barrier is poor visibility. Even when tanks are installed, users may not know how much water is available at any given time. That creates uncertainty and can lead to underuse of stored rainwater or unnecessary reliance on mains supply. Smart tank level indicators solve that problem by making available water visible in real time.

There is also a perception issue. Some people still think rainwater is only suitable for rural homes or isolated sites. In reality, Level notes that rainwater can be part of a building’s water supply, provided the installation meets relevant Building Code requirements and contamination risks are managed properly. That makes rainwater a much broader option than many people assume.

What makes rainwater harvesting safer

Collecting rainwater is only valuable if the system is designed well. Level’s guidance explains that roofing, gutters, downpipes, and pipework need to be suitable for collecting rainwater, and that first-flush diversion and leaf screening help reduce contamination. Those are basic but important safeguards.

That means rainwater harvesting in 2026 should be discussed as a system, not just a tank. The roof is the catchment. The plumbing is the delivery route. The tank is the storage point. The indicator is the visibility layer.

When those pieces work together, rainwater collection becomes far more practical. You are not just storing water. You are managing it in a way that improves reliability, reduces waste, and supports more confident use.

Why monitoring is part of the answer

Rainwater collection and water level monitoring go hand in hand. A tank that cannot be monitored effectively is harder to manage, especially when demand changes across the week or season.

This is where Smart Water’s core product category becomes relevant. Internal monitoring tools and tank indicators help users see how much water they have, when it is being used, and whether the system is operating as expected. For properties trying to make rainwater part of everyday supply rather than a backup only, that visibility is essential.

Smart Water’s product ecosystem also helps support the buying journey:

The business case

The strongest argument for proactive rainwater collection is not just environmental. It is operational. Capturing rainwater can reduce dependence on mains supply, lower exposure to restrictions, and create a more flexible water system that performs better during dry spells.

For households, that might mean fewer supply worries and better garden or outdoor water use. For farms and lifestyle blocks, it can support livestock, irrigation, and washing needs. For businesses, it can improve continuity, reduce costs in some use cases, and make water management more resilient overall.

There is also a competitive advantage for organisations that treat rainwater as part of their sustainability story. Customers and stakeholders increasingly want evidence of practical action, not just broad environmental claims. Rainwater harvesting is a visible, understandable, and measurable action that can support that story.

Smart Water: Monitoring for Efficiency

Whether you're in a residential, commercial, or agricultural setting, monitoring your water tank levels is crucial for efficient water management. Smart Water provides state-of-the-art monitoring systems that deliver accurate water level readings via an easy-to-read display or our app. Our award-winning technology helps you track water consumption and make informed decisions about water usage.

A Call to Action

New Zealand needs to be more proactive in collecting rainwater. By embracing rainwater harvesting, utilising innovative solutions like slimline tanks, and leveraging smart monitoring technology, we can reduce our reliance on mains water supplies and create a more sustainable future.

FAQs

Why should New Zealand collect more rainwater?

Because rainfall is a valuable local resource, supply pressure remains real, and rainwater can improve resilience for homes, farms, and businesses.

Is rainwater harvesting already common in New Zealand?

Yes. Level notes that about 10 percent of the population depends on roof-collected rainwater for drinking water, which shows it is already widely used.

Does rainwater collection need to follow building rules?

Yes. Level explains that rainwater systems need to meet Building Code requirements and manage contamination risks properly.

Why are tank level indicators important?

They help users know how much rainwater is available, which makes stored water easier to use efficiently and reliably.

What kind of properties benefit most from rainwater harvesting?

Homes, farms, lifestyle blocks, commercial sites, and any property that wants greater water resilience can benefit.

Where can I learn more about Smart Water products?

You can explore the product range, starter packs, about us, testimonials, and where to buy pages.

First Published 29 October 2021 and Last Updated 28 May 2026