Water harvesting has become an essential part of any Australian household over the last few years. This is because water is becoming a scarce resource by the day and we are all trying to collect as much of it as possible. For the longest time, rainwater went to waste especially in Sydney, where the annual rainfall could be as much as 1400mm in areas such as Turramurra. However, water storage has grown so much that you have several options when it comes to choosing tanks. You can have an above ground water tank installation, or an underground tank, with the above ground type further being split into round and slim-line tanks.
Does size matter?
For most people venturing into water harvesting, they would like to get as big a tank as possible. This is why the question of the largest capacity for a residential water tank available has become so common. Most underground water tanks are limited in size by the amount of work that goes into the installation process. The largest size that we have come across for in-ground water tanks was 10,400 litres. It is important to note that should you require more storage, but you are set on all your tanks being underground, two or more tanks can be linked.
When it comes to above ground tanks, the sizes stretch a little more. This is however limited to round tanks alone. Slim-line tanks by definition, are created to offer the most storage capacity possible while taking as little space as they can. This has limited the largest tank we have encountered to 5000 litres. Round tanks on the other hand is where the size debate ends. Most of them fall within the 3,900 litres to 13,500 litres range, but that is not the upper limit in capacity. There are tanks that can hold up to 22,700 litres, with the largest tank size we have come across, that can be used in a residential setting, being 34,000 litres. Round tanks are therefore what you need if you are looking to add to their water harvesting arsenal.
What determines how much capacity you need in a tank?
The question about capacity is usually accompanied by how you determine what tank capacity is best for you. This is determined mainly by three main factors namely:
- How much water do you need
The question of your water needs is established by what you are going to use the water for once you have it. The more water you use in a week, then by default, the larger the size of the tank you are going to need. For instance, people that use harvested water purely to water their garden will typically use about 1000 litres in a week. These can do well with tanks that hold between 10,000 and 13,500 litres of water. In comparison, people that have more water usage for example cleaning the house, flushing the toilet, cleaning the car, and washing the driveway, will could use up to 5000 litres a week and would benefit from larger tanks of 18,000 litres to the 34,000 litres.
- How much water can you harvest?
This is going to be determined by the size of your roof. Typically, every square meter of roof will collect about a litre of water, for every millimetre of rainfall. This means that in an area that receives 1400 millimetres of rainfall in a year, that square metre of roof will collect 1400 litres. The easiest way to calculate the tank capacity you require would be to take the area of your roof that can be connected to the tank and multiply it by the amount of rainfall projected in your area. For instance, a 200 square metre roof will have about half connected to the tank, which means that it is capable of collecting about 1000 litres for every 10 millimetres of rainfall.
- How much space do you have?
Water tanks take up space; a 34,000 litre tank will definitely need a lot of space to work with. This is why when you are considering a large capacity tank, but do not have the space, you can opt to link two or more tanks. This also works to safeguard your water collection in case one of the tanks develops a problem, for instance a slow leak. Linking tanks works best when you have a long but narrow space to work with, where a round tank may not be able to fit.