It’s a no-brainer: recycling water not only saves you money, but allows you to use water in more ways. Wash your car with a clean conscience by using water from the shower. Keep your garden green through water captured from rain or from your washing machine. Store water long-term for those dry periods, such as winter months or South Africa’s current drought.

But not all types of water are the same. Here are the three categories, what to use them for and how to store them…

What are the Different types of Water?

The typical home and business generates three types of water. Actually they are all the same thing – water – but it’s what gets trapped inside that makes the difference.

Rainwater doesn’t come from your building directly and instead falls from the sky, as the name suggests. But the main catchment area is the roof, which means whatever accumulates on the roof mixes with the rainwater. This is normally organic matter such as leaves and the droppings of birds.

Greywater is water that was used for various tasks, such as washing machines or showers. Greywater tends to have some chemicals in it, like the detergents or soaps used to clean something.

Blackwater is water that has a lot of organic waste in it. This often refers to sewage, but the water from dishwashing also qualifies.

What can I use each for?

Rainwater can be used for pretty much anything you need water for. You can comfortably use rainwater for flushing toilets, washing clothes, watering gardens and more. You can even drink rainwater, though you may have to filter the water to remove any organic material that got mixed in through the catchment process.

Greywater can be used to replenish toilets, washing machines and most systems that aren’t for consumption (such as drinking or cooking). It really depends on the chemicals inside the water. You can conveniently keep your grass happy with water from a washing machine to, but it may not be ideal for pot plants or food crops. Greywater can be used for those, but may require filtering or treatment, depending on the chemicals involved. For example, water captured from a shower isn’t as damaging as water from washing clothes, since it uses fewer chemicals (hand soap, shampoo) than clothes (washing detergent, fabric softener).

Blackwater shouldn’t be recycled or used without serious precautions. Not only can it contain organic material such as food particles, which can degrade very quickly into toxic substances, but it likely already contains substances that are already toxic, such as excrement. It is possible to recycle blackwater, but this requires very specific treatments.

How do I capture and store these?

Rainwater is pretty obvious: when it rains, you capture the downpour. Your roof is by far the biggest and best way to gather rainwater, especially if you have gutters that can be directed to tanks. You should use filters to stop debris.

Greywater is a bit trickier. You can capture the water by connecting tanks to outlets for shower drains, washing machines and such. If you want to go low-tech, place a bucket in the shower, but there are affordable automated systems that can easily be installed by a professional. Greywater should not be stored for longer than 24 hours.

Blackwater shouldn’t be captured without proper precautions. If you do intend to recycle blackwater, invest in a professional septic system that can use chemicals or organic biomes to clean the water. Blackwater – even when cleaned – should not be stored but instead used as soon as possible. A common use is direct irrigation of lawns and gardens. Again, only do this after the water has been purified.