You may be thinking about going off-grid. Or not completely off-grid, but you want to make your house more sustainable. You will pay attention to your waste and consumption. But also to how you get your primary supplies or resources. And water is one of them. If your property is not connected to a mains water supply or located far away, rainwater collection is an excellent alternative for house use. If you are connected to a water supply, you can still consider it. It will be a way of reducing your demand for water and contributing to sustainability. You can consider the combination of both sources.

Using rainwater is a great alternative. It is inexpensive and setting up the logistics to use it is simple. And you will have a lot of benefits! You can use it for your garden, for washing your clothes, or for flushing the toilet. If you are also considering a treatment or purifying device. You can use rainwater for drinking, bathing, or cooking. 

It’s quick and easy!

Using rainwater in your house use is a very easy setup. The collection system is simple. Rainwater is collected from the roof or any other surface and then stored in a tank. You can then use it when you need it. Simple as that! The details of the system will depend on the amount of water you use, as it will be the amount you will need to collect.

To calculate the size of the tank you need you will have to consider different things. First, the annual rainfall in your area. Then, whether you have access to the main water supply or not. Also, the use you will give to the water, together with how reliant you will be on this water supply. You will also have to consider the size of your property and the size of the collection area.

Simple as it sounds, to collect rainwater for outdoor use you will only need a drum or barrel. You can consider a 44-gallon drum or a 200-liter rain barrel with a tap or connection to a soak hose. To be able to water your garden with rainwater the system only relies on gravity and doesn’t need pumps. If you live in an area with year-round rainfall, a smaller tank might be enough. If you have very dry summers and you need to water your garden more often you will need a larger tank. As this tank doesn’t rely on a pump and it is a gravity-fed system, it will only need a stand. It needs to be robust and should be concreted into the ground.

How many liters?

To be able to use rainwater for indoor supply, you will need a larger tank and a pump to operate. If you are able to combine rainwater with your main water supply, a 5000 liters tank will be enough. You will be able to use rainwater for your house in areas with year-round rain. If you have dry summers you will need a larger one, of more than 10,000 liters. If you are considering rainwater as your only source of water for house use, you will need at least a 30,000 liters rainwater tank.

In regards to materials, it depends on the size of the tank and the use you will give to the water. The location where you will place it and your budget is also important. The most common for tanks are plastic (polyethylene). You can also consider concrete or coated steel.

Thinking about costs? A basic rainwater collection tank for your house is not expensive. You have to consider material, installation, and transportation. If you are considering indoor use, you will have to consider plumbing requirements and pipes. Also, filters or treatment and building consent fees, if applicable.

You will also have to consider legal requirements. Some councils will only let you use rainwater for potable purposes only if it has been treated. If your house is already connected to a mains supply, you will need building consent and annual inspection fees.