18 May 2024

Why rainwater tanks are good for the environment

The water tank revolution is once again sweeping New Zealand and countries around the world. Many homes are choosing to invest in a water tank as a way of saving money, especially if they plan to live in that house for a long time. Harvesting rainwater from your roof can save you hundreds of dollars on your water bill, and over time, your initial investment in a water tank will pay for itself and more.

Cost savings are not the only good reason to install a water tank. With hotter summers leading to water restrictions across New Zealand, Australia and the USA, a water tank is a great way to ensure you have access to clean water all year round. Whilst many people are forced to stop watering their gardens when water restrictions come into play, those with water tanks can continue to water all year round, keeping their gardens in tip-top shape.

In this post, however, we want to go beyond the cost savings and the practical benefits of having your own on-premise water supply. In this post, we are going to feature the environmental benefits of installing a water tank on your property.

Environmental benefits of installing a water tank

Water tanks have long been used in New Zealand and Australia, especially in remote areas where access to mains water was very limited.

Of course, over the past 20-30 years, mains water has become more accessible to even the most remote areas, reducing the reliance on water tanks. Fewer homes in New Zealand and Australia were fitted with water tanks in the 90s, 2000s and 2010s, however, they have been making a comeback.

Today, awareness about sustainability and environmental issues has driven a resurgence in the popularity of water tanks. In some places, there are incentives available for people building new homes to install a water tank, and in other areas, water tanks are compulsory for new builds.

There are a number of environmental benefits that come from installing a water tank. Tanks today come in all shapes and sizes, making them a much more practical addition to a property. Traditional water tanks were huge concrete structures that were difficult to screen and also required a lot of space to install.

Today, slimline tanks can be installed along fence lines or alongside properties and come in a range of colours that can blend in with the overall property. This makes them much more appealing as well as being a more practical installation.

With more people installing water tanks in their homes, let’s take a look at some of the environmental benefits:

Managing stormwater

As the world’s population continues to grow, more and more people are moving to cities. As urban migration continues, with the United Nations predicting that 70% of the world’s population will be living in cities and urban areas by 2050, cities will increase in size by roughly 2.5 billion people over the next thirty years.

That places a lot of strain on the water systems in cities around the world.

Rainfall that used to infiltrate through the soils, or slowly drain overland, runs much faster across sealed surfaces, and into the piped stormwater network.

This will continue to increase as cities grow and climate change creates more extreme rainfall events.

This increase in stormwater runoff leads to a whole range of problems, from flooding to pollution. The more water tanks that are installed in domestic properties, the less runoff into stormwater drains and the more those systems can function how they are supposed to.

Without rain harvesting, the sheer volume of stormwater, which is typically rapidly channelled into nearby waterways erodes creeks, deposits sediments, and pollutes and destroys water habitats and organisms.

This has a significant impact on these environments and the water quality in our lakes and streams becomes compromised, not to mention the runoff into our oceans.

Reduce carbon emissions and energy use

Whilst reducing carbon emissions and reducing energy usage might not seem like an obvious benefit of installing a water tank, the cumulative impact of more homes collecting water can have a significant impact on the amount of energy needed to process both mains water and wastewater.

A lot of energy is required to treat water in the wastewater system and then pump it around the system again. Houses that become more reliant on the rainwater they collect on their own properties help to reduce the amount of energy required to treat and process water in the mains system.

Even if you are only using the rainwater you collect to water your garden or wash your car, the marginal gains on the system add up as more and more people commit to rainwater harvesting around the world.

Replenish groundwater supplies

As well as helping to reduce the amount of stormwater run-off, rainwater tanks help to keep groundwater levels replenished. Instead of the ground becoming saturated when it rains, with nowhere for that water to go, a rainwater tank holds that water in one place and this is then released back into the ground through watering when the ground is not saturated.

This helps to keep the water table at a more manageable level, helping to hydrate the soil when it is required rather than simply relying on the natural rain. This helps to keep groundwater supplies replenished throughout the year rather than seeing the level yo-yo through the wet and dry seasons.

Reduce the demand on groundwater supplies

In most countries around the world, water reservoirs and groundwater supplies are usually overdrawn. This has certainly been the case in Auckland over the past five years, although the last two wet winters have replenished our reservoirs in more recent times.

Over over-dependence on mains water that is drawn from reservoirs puts increasing strain on the infrastructure and in the next decade, many places can expect water restrictions to be put in place as we face drier summers.

As more properties add water tanks, collecting the rain that falls naturally on roofs, we reduce the overreliance on already stressed systems, giving them time to replenish as well as enabling households to have access to clean water all year round, even if restrictions are put in place for the use of mains water.

Greener gardens

As well as benefits to the overall environment, collecting rainwater can also help with your own ecosystem on your property.

Rainwater is full of nutrients that are great for the plants in your garden as well as your grass. Have you ever noticed how green your plants are following rainfall compared to when you water them using mains water from a hose?

Rainwater is free from chemicals and salts that are typically required to treat mains water so that it is safe for drinking, bathing and cooking with. These chemicals and salts alter the composition of the soil when you water your garden, which in turn impacts on the plants and grass.

Rainwater has a much more balanced pH which your plants will love, as well as containing other nutrients such as nitrogen, phosphorus, potassium, calcium, magnesium and sodium. Nitrogen in particular acts as a fertiliser for plants and vegetables.

You can read more about the benefits of rainwater for your garden in our recent post.


Harvesting rainwater has many benefits for the environment, many of which you might not have even considered.

Water tanks bring so many benefits, not just environmental and you can read about some of these benefits in our other posts listed below.

When it comes to managing your water and monitoring your usage, Smart Water has a range of solutions to help you to keep on top of your consumption and ensure you manage your water usage efficiently.

Easy to install yourself, your Smart Water tank indicator provides you with all the information you need from our app or from one of our LCD displays. Find out how much water you consume on average from your tank, accurate pressure data and estimates on when your tank will run out of water based on current usage.

Find out more about our range of products or check out our FAQs for more information.

Related Posts

·        Collecting and using rainwater – a beginner’s guide

·        How much rainwater can you harvest from your roof?

·        Is rain harvesting worth it?