Rainwater harvesting

The size and type of the rainwater collection system that you can install will depend on your individual property and what you want to use the water for.

Rainwater barrel

The easiest system to install is a rainwater barrel. These can be used for watering the garden and don't require a pump or treatment system. Rainwater is great for your garden because soil doesn’t require water to be treated first.

What to consider:

  • To collect rainwater from your roof, you will need to connect a diverter to your downpipe.
  • Location – the barrel needs to be secured and on a slightly raised platform e.g. pavers/pallet as it relies on gravity to work correctly.
  • Managing any overflow – installing a diverter is a good idea to direct overflow back into the stormwater system to reduce ponding on your property.

Learn what items you need to build your own rain harvesting kit (written by EcoMatters).

Download the Eco Matters guide

Rainwater suppliers

As well as the big DIY stores there are smaller operators that sell rainwater harvesting barrels.

The list of suppliers* below is just a starting point and does not imply that Smart Water endorses or approves them. Please take the time to do your own research using internet search terms such as ‘rainwater barrel nz’; ‘rainwater harvesting nz’ or ‘rainwater tank’ and the nearest large town where you live e.g. ‘rainwater tank cambridge’.

 *If you are aware of a supplier who you think should be added, please contact us

Rainwater tanks

Rainwater tanks may provide all or some of your household’s water needs.

We recommend contacting a local rainwater tank supplier to get the right advice on what size and type of tank will best meet your needs and the needs of your property. The requirement for whether your tank may need a building consent depends on:

  • the size of the rainwater tank
  • what you want to use the water for
  • your location.

Contact your council’s building consent team to find out more. 

For more information check out the Smarter Homes guide to rainwater tanks.

Want to see what an installed rainwater barrel actually looks like?  Go Eco, based in Hamilton, have established a learning area with an operating rainwater barrel and garden. Contact Go Eco to organise a time to have a look at the system and learn more about what you could install in your own garden. Visit www.goeco.org.nz or call on 07 839 4452.

Heather's rainwater barrel

Heather's DIY rainwater barrel costs $50

With a tiny backyard, I was keen to collect rain water to use on my garden.  I also wanted to reduce my environmental footprint by using less tap water (council-supplied water requires electricity to treat and pump it through pipes). 

My challenge was to build a rain barrel for less than a DIY shop equivalent.  I am pleased to say I managed to achieve this for less than $50, a saving of $150.

I sourced a free barrel from a friend and rinsed it out several times on my lawn.  After choosing where to place the tap at the bottom so the angle was right and it wasn’t too close to the bottom, I drilled a 28mm hole using a flat-head drill bit ($16).  This bit was fun – straddling the tank to drill the hole then fit the tap ($9.30).

I used a nifty trick from this video to install the tap inside the barrel using a weighted string and slid the tank tap fitting with the rubber washer ($9) down this.  I cut 2 (free) pallets in half to get the correct height so that a watering can would fit underneath.  This was the barrel complete. 

I didn’t have spouting on the shed, so improvised some guttering from some scrap corflute I salvaged and screwed this to the shed wall.  For the transition from spouting to hose fitting I used a milk bottle with the hose connector glued into the lid.  I then connected a short length of garden hose into one of the screw openings in the top of the barrel with some flyscreen around it to stop mosquitoes.

While this is a hobby-sized water barrel, linked only to half my garden shed roof (2m2), I was pleasantly surprised how much water I got after each wet day.  Plus I easily completed it for less than $50.

The next steps would be to connect a second tank as an overflow from the first, and also to secure the tank(s) to the fence using some metal tape used to secure hot water cylinders so it doesn’t topple during an earthquake.  After that I’d look at something more serious for the house – a larger tank and cutting into the downpipes, but for now I’m happy with my little trial tank.

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