Rainwater Tanks

A water tank being set up during a working bee. (Photo: Selina Cheng)

When it rains, we let a huge amount of perfectly good, clean, free water run off our roofs, driveways, and roads and down the drain, while paying for water to be treated and pumped to our homes. It’s crazy, especially during drought and water restrictions. A rainwater tank can be an important investment for your edible garden and your sanity.

Even with the drought, Sydney has had annual rainfall of 1000 millilitres in the past 2 years. A roof area of just 250 square meters can catch 250,000 litres of rainwater each year! Even with small losses through splashing and evaporation, that’s a lot of water.

Before you invest in a tank, make sure you do the maths and get the best option for your property, your current needs, and your future dreams. Work out how much you could catch and store, and how much you really need. We could have regular hot Sydney summers with little rain and water restrictions, so ideally you need to store 3 months worth of 8–10 litres of water per day for every square metre of garden bed, and 5 litres for every established fruit tree.

If you are already reusing mains-supplied water from showers, sinks, and washing machines (known as grey water) for your garden, you can get away with a smaller tank. If you want to use rainwater for washing and for flushing toilets, then get a bigger tank now, or an adaptable system which you can add smaller tanks to later. If your goal is to supply all your household’s needs from rainwater then obviously the bigger the better!

Think about where you have space for a tank and where best to put it so you can use gravity to get water where you need it, instead of a pump (although you might have limited choice in this). You might think you don’t have the space, but there are many options for tanks now, including a series of small tanks, slimline tanks for narrow vertical spaces, and bladders that can sit under your house or veranda. The Very Edible Gardens website has many more great tips on rainwater tanks.

What if you are renting or live in a flat? You can still divert downpipes to small moveable tanks, and catch water in barrels, tubs, or even a small pond in a pot. And don’t forget all the other smart ways to catch, store, and use water. Water is life, don’t waste a drop.