World Water Day is focusing on wastewater, here's why

Eighty percent of wastewater flows back into the ecosystem

Wastewater can be contaminated after it is used in any number of processes – industrial or agricultural or domestic – and is left untreated. This water can seep into water supply lines or make its way back into the ground or rivers or lakes.

And when people consume this contaminated water, it causes illness and disease.

Approximately, 1.8 billion people use drinking water contaminated with faeces, putting them at risk of contracting cholera, dysentery, typhoid and polio. Unsafe water, poor sanitation and hygiene cause around 842,000 deaths each year.

Over nine percent of the world's estimated population is using "unimproved" drinking water

Such sources include unprotected springs, wells, tanker trucks and water which stagnates – all of which are open to wastewater contamination. At least 663 million people – twice the population of the US – are using unimproved drinking water sources. Nearly half of them live in sub-Saharan Africa and one-fifth in South Asia.

Once it is treated, what can we use wastewater for?

There are many ways to make the most out of wastewater once it is purified and treated, including discharging it back into local water sources.

Domestic users can water their gardens with it or wash their cars with it.

Industrial consumption amounted to 22 percent of global water use in 2012. Industries are now seeing the benefit of reusing its wastewater. Some use it for cooling or heating units, such as boiler systems. This can save hundreds of thousands of cubic metres of water locally.

If properly treated, it can be converted into drinking water.

Agriculture is the biggest consumer of water and ground water contamination and recent droughts have led farmers to understand the need to recycle water safely. Israel recycles its sewage water and then sends it to farms, something the desert country has tried to develop at all costs.

It's both a rural and urban problem

Rural areas lack access to clean water supplies because of a lack of development. Millions in countries like India and Pakistan use wastewater without treating it.

But by 2050, 66 percent of the world's population will have transitioned to urban living. Most cities in developing countries are not equipped with adequate infrastructure, not the kind needed to manage wastewater.