Saving Water : The Benefits of Using a Water Tank

This is the second article in a 6 part series on Saving Water (see part 1 on ). Living in Sydney, Australia I’m acutely aware of the value of this precious resource.

Slimline tank, SydneyToday we’ll be looking at something for home-owners worldwide – the benefits of using a water tank. A rainwater tank, that is.

When I was growing up in Sydney there was no thought of restricting water use. It was common to see people watering their lawns in the evening, washing the car (with a high-pressure hose) on the weekend and standing under the cool, running water on a hot day.

In recent years (over the past decade or so), the idea has been gradually spreading that water is a valuable resource. This is particularly evident during periods of drought, when water restrictions are in place.

One thing that has made a massive difference to the amount of water we have available – taking us back to the ‘good old days‘, if you like – is the installation of a water tank. If you haven’t really thought about putting one in (regardless of where you live), here are a few things which might just have you considering the idea.

What is a water tank?

Firstly, let’s take a step back and make sure we’re both thinking of the same thing. I’m simply referring to a rainwater tank (aka rain barrel), which is simply a large container that collects the water from your roof when it rains; allowing you to re-use that water at other times. Most tanks have a tap near the base, and a common use is to connect a hose and use the water to keep the garden happy.

Of course, there are a number of other things you can do with that water – ranging from looking after your pets to use in dishwashers and washing machines. And the ultimate use; you can drink it.

Types of water tanks

Round tankRound and slimline : Tanks come in a variety of shapes and sizes, designed to suit a great range of accommodation. For existing homes there are large, sturdy outdoor models (in a range of shapes, sizes and colours). These just need a solid, flat surface (a small concrete slab or a paved area) somewhere near the guttering. Redirect a downpipe, set up an overflow, and you’re good to go.

NB : An option may be to bury the tank beneath a garden or lawn. Although it takes a bit of work to set up, it’s completely hidden from view. Perfect.

Bladder tankBladder : Newer homes often take advantage of the massive, inflatable bags which are designed for use under floors or decking. Although it’s possible to install these in existing homes, it’s much easier (and cheaper) to design the floor with the bags in mind.

If you’re living in an apartment or other type of shared accommodation, it’s worth talking to the person/people in charge of things there. Not only is it a sensible and environmentally-friendly approach; it’s often much, much cheaper.


RainsaverRainsaver gutter / tank : these tanks are hidden with a fairly typical guttering system, and can hold a surprising amount of water. A notable example is the RainSaver.






MatrixUnder gravel, paths and gardens : I love the idea of these – particularly for new homes or during major landscaping work.

The tanks resemble milk crates (with a finer mesh, of course), and are buried beneath gardens, paths and driveways. Excess water works its way down to them, where it is stored for later re-use. A beautiful setup.

Atlantis are the best tanks of this type I’ve seen, and there are some excellent resources on their site looking at this approach.

Benefits of tanks

Piggybank water tankThere are several reasons to consider setting up a water tank or two. They are :

Cheaper : When it comes to saving money, this one’s definitely on the shortlist. After all, rainwater is cheaper than the stuff you pay to have piped in.

The only costs to offset that (and these are one-time-only) are the price of the tank itself [rebates are often available], and the installation.

NB : The installation isn’t particularly difficult. If you’re DIY-inclined you can probably do it yourself; otherwise it’s time to call the local plumber or guttering expert. The company which sold you the tank may even install it for you.

Add value to your property : Unsurprisingly, homes with reduced – or no – bills do somewhat better than their conventional counterparts (everything else being equal). Reducing or eliminating the need to buy water can increase the value of your home.

You’ll use less water : Like a lot of things, knowing you ‘can‘ is often enough. Once the tank is in place, you may find yourself using a little less water – simply because you know it’s there, if you need it.

What size tank do I need?

Water tank at Sade BokerThis depends on three main things :

  1. The amount of water you’re using currently (see the first part in this series – for the answer to this)
  2. The space you have available, and are allowed to use
  3. Your financial situation (see the section on Rebates – these may make it a much more reasonable proposition)

Tanks range in size from just a few hundred litres to hundreds of thousands; so there’s bound to be something to suit your current needs. A family home may only require 10,000 litres or less to completely look after its water requirements. That’s for the garden, washing, cooking, drinking – everything.

To find out your own household water use, take a look at the first article in this series – How to Measure Your Water Usage.

How long will it take to fill the tank?

RainTo get an idea of the time it’ll take to fill the tank, you’ll need to know two things :

  • the rainfall in your area (an approximation is usually available online, or you can measure the actual rainfall on your property)
  • the area your roof covers (although the material, pitch and installation of your roof all play a role, the area will give you a pretty good idea)

As a guide, 1 square metre of roof will catch about 1 litre of water for each mm of rainfall.

Replacing the household water supply

Although the simplest use for a water tank is to store rainwater to look after the garden on dry days, they can certainly be used to help with any water needs around the house.

The tank’s installer will give you an idea of cost here (if you installed it yourself, just call a local plumber).


CashAlthough the price of tanks has fallen slightly in recent years, they still require a bit of an investment. One thing which may help is a government rebate.

As these vary from state to state, country to country; it’s worth taking a look to see what’s available in your area. To give you an idea though, here are several of the more common approaches :

In the US : The rebates vary from state to state, and even between water suppliers. The ones listed at Water Saving Hero are fairly typical (these ones apply to residents of California); RainMaster has a more complete list of water conservation and rebate sources here.

In Australia : Rebates here also vary from state to state, with a few of the typical schemes outlined on the Rain Harvesting site.

In the UK : Although rebates are slightly more difficult to find, there are a few available. A good starting point is the Surface Water Drainage Rebate; followed by a phonecall to your local water supplier.

NB : One of the easiest ways to find out what’s available locally is to ask the salesman at your local whitegoods store. If they sell washing machines and dishwashers, they’ll know where to look.

Other considerations

Cleaning the roofWhen setting up your rain harvesting system, there are a few things which will keep the process nice and smooth :

  • A clean roof = greatly reduced need to filter the water. If you’re planning to have your roof scraped, repainted or treated in any way; do this before you set up the tank.
  • As a secondary precaution, throw away the water from the first fill of the tank.
  • Adding a screen to the top of the tank will keep leaves and other large debris out of your water supply.
  • Use an overflow device to redirect the excess water when the tank is full.
  • Check gutters, downspouts and overflows regularly to make sure they’re not blocked.

Final thoughts on the benefits of using a water tank

I love the idea of putting fresh, clean rainwater to work – at the very least, storing it ready for watering the garden on dry days.

Regardless of whether you own your own home, share accommodation or rent; the benefits of using a water tank are well worth considering.

This is the second article in this series on Saving Water. If you missed it last week, you may also like to check out the first part, the all-important How to Measure Your Water Usage. Good fun.

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