What is the best rainwater tank for your property?
Rainwater harvesting is becoming increasingly popular as people seek to become independent from the main water supply and utilize rainwater collection as a more sustainable and regulated water supply. This can be for drinking water, irrigating gardens, or for a home’s entire water supply, and water storage.
However, there is a huge range of water tanks available in today’s market, and wading through slimline tanks, poly water tanks, fiberglass tanks, concrete tanks, and steel tanks can create real headaches. The prices of these rainwater tanks. Rainwater harvesting shouldn’t be that difficult, and knowing what rainwater tank or rainwater tanks will be best for your property helps shorten your list of options and get you harvesting rainwater sooner.
The type of available space on your property, your rainwater harvesting ability, and what you intend to use your water storage for will all influence the best choice of water tank for your home.
How much water can I harvest?
Before we move on to the best rainwater tanks for each scenario, let’s work out your total water harvesting ability.
First, you want to work out your total rainwater collection area—any shed, home, or barn roofs—in square meters. If you live somewhere that uses the imperial system, make sure to convert this, as the equation only works in metric.
Next up, you want to find your local annual rainfall. If you’re the kind of person who takes rainwater measurements for your home, then you’ll have these figures; if not, check with your local council or any neighbors to work out this number in millimeters.
And finally, it’s time to combine these figures. For every 1 mm of rainfall and 1 m2 of rain harvesting area you have, you will be able to collect 1 liter of rainwater for your water storage. As an equation, it looks like this:
Annual Local Rainfall (mm) x Rainwater Collection Area (m2)=Annual Rainwater Harvesting Ability (L)
So, for example, if your local rainfall is 895 mm and your rainwater collection area is 165 m2, then you would be able to harvest 147,675 liters of rainfall each year. If you expand your collection area to include an extra shed or the tank roof itself, this figure will increase.
This will give you an idea of the maximum annual rainfall you can expect to be able to divert to your rainwater storage and allow you to work out the largest rainwater tank you could need.
The best rainwater storage tank for your needs
Supplying water to the entire home
If you are looking to supply water to the entire home, you’re going to be looking at the higher end when it comes to tank size, as you are seeking to use rainwater for every aspect of your home water supply, be it drinking water, showering, gardening, or washing dishes.
When asked what size rainwater tank you would need to be looking at for a family of four, Pioneer Water Tanks in Brisbane said that they recommend a minimum 150,000 liter (about 40,000 US liquid gallons) water storage tank.
However, if you can harvest more than this and afford a larger tank, this is often recommended, as this figure doesn’t take into account things such as fire reserves, gardens, or lawns, which will increase your water usage.
For this amount of water storage, steel rainwater tanks with a food-grade or antimicrobial liner are likely your answer. They are significantly cheaper and easier to repair than a concrete tank or stainless steel tank, and since poly water tanks usually only come in sizes of up to 50,000 liters, you may require two to four poly tanks to get the same rainwater storage capacity as a single steel tank.
The rainwater tank installation of these steel tanks is performed by an experienced water tank installer on a pad constructed from concrete, gravel, or sand, and they are usually able to be installed in one day. Many, but not all, of these installers are also licensed plumbers and will be able to assist with the fitting of a water pump or first flush diversion system, as well as plumbing the water tank into your home water supply.
Water for one or two uses
With a backyard
If you’re looking to use your tank water as a support to your main water supply—perhaps just using it for gardens and the laundry, or even just for drinking water and in the kitchen—and if you’re concerned about your water quality, then poly rainwater tanks are your best bet.
Poly tanks are made from food-grade polyethylene that is UV-treated for the storage of water, and, unlike steel tanks, there is limited rainwater tank installation required, as a poly tank comes completely pre-built and in one piece and simply requires hooking up to the gutters and plumbing to the desired outlet.
Your poly rainwater tanks can come in the standard round tanks or more of a squat tank model if you need to fit them under an awning or roof, or simply don’t want them to be too tall. These are best for large suburban or semi-rural properties, as poly tanks are usually from one to four meters in diameter and will take up a bit of your available space.
In the 1000- to 50,000-liter water storage space, these medium- to large above-ground tanks provide a great option for many households.
With limited backyard space
If you don’t have the space for a larger round poly tank or a steel tank, there is a range of plastic rainwater tanks that are much more space-conscious and can help you meet your water harvesting needs even on smaller blocks.
Slimline rainwater tanks are thin, long polyethylene tanks designed to fit under an awning or under a gutter for stormwater runoff and are typically only a meter or so wide and up to 10,000 liters in size. This allows the installation of one or more of these plastic tanks down the sides of houses or sheds without sacrificing the limited space in these backyards. These poly water tanks are akin to rain barrels, only designed with larger and more efficient water storage in mind, without needing as many small tanks.
Underground tanks are another great option for those who don’t want their tanks to steal any of their backyard space. An underground tank is a plastic water tank designed to be buried under a lawn or garden bed, much like a septic tank might be. The main drawback of underground tanks is that if something goes wrong, they are harder to access and repair.
The other option for those looking to have a rainwater harvesting option without the associated space is a bladder tank. These tanks can be installed under decking in the front or backyard, or in a reinforced roof or attic. These tanks are quite simply bladders with a frame, so it is important to ensure that they are safe from elemental damage or the potential of puncture.
What to do if you are unable to harvest or store enough water
For those unable to harvest enough rainwater to meet their needs, particularly those unable to access the mains water supply, installing a greywater harvesting system to support your rainwater storage can greatly reduce your water usage.
These water recycling systems reuse water from the bathroom and laundry, reusing this water in the garden, toilet, or both. With how much water is used in the shower and washing machine, coupled with the water supply needed for flushing a toilet and regular irrigation of a garden, a greywater setup can help take your rainwater supply that extra mile.
What to do next
Once you have a better idea of the best rainwater tank for your home, you can make a much smaller list of options and suppliers and start making phone calls.
Make a list of prices, sizes, and features from each water tank company, as well as lead times if you want the water tank installed sooner rather than later, and you will soon have a much clearer picture of the best company and best water tank for your home.
Good luck, and happy harvesting!
