World Water Day (WWD) is about taking action on water issues. It focuses attention on the importance of freshwater and advocating for the sustainable management of its resources. Held on 22 March, World Water Day tackles a specific aspect of freshwater each year, raising awareness of what society can do to help make clean water more accessible. The theme of 2017 is "Why waste water?" which focuses on reducing and reusing wastewater.

World Water Day 2017
World Water Day 2017
World Water Day 2017
World Water Day 2017
World Water Day 2017

Wastewater is any water that has been adversely affected in quality due to human activity. The vast majority of all wastewater from our homes, cities, industry and agriculture returns back to nature without being treated or reused. This causes mass pollution to the environment, while losing valuable nutrients and other recoverable materials – so instead of wasting water, we need to be reusing it.

The Sustainable Development Goal 6 target aims to halve the proportion of untreated wastewater and to increase water recycling and safe reuse by 2030 – and by then the global demand for water is expected to grow by 50%.

World Water Day 2017
Palestinian fishermen are reflected in wastewater as they prepare their boat on a beach in the central Gaza Strip on 26 June 2014Mohammed Salem/Reuters

The UN target aims to help improve water quality by reducing pollution, eliminating dumping, minimising release of hazardous chemicals and materials and to substantially increase recycling and safe reuse globally. In doing this, it will help us to achieve safe water and sanitation, affordable and clean energy, sustainable cities and communities, while improving life on land and in the sea.

World Water Day 2017
A child stares into a narrow duct that typically runs through slums with tin shacks crowding around the water's edge, where residents have been dumping trash for decades due to the lack of a proper rubbish disposal system in Jakarta, Indonesia on 29 December 2016Goh Chai Hin/AFP
World Water Day 2017
A devotee carries a statue of the Hindu god Ganesh, the deity of prosperity, to be immersed into the polluted waters of the river Yamuna on the last day of the Ganesh Chaturthi festival, in New Delhi, India on 27 September 2015Adnan Abidi/Reuters
World Water Day 2017
A volunteer clears rubbish from the Ciliwung River in the Jatinegara district of Jakarta on 3 December 2017Beawiharta/Reuters
World Water Day 2017
A river filled with garbage is seen in Manila, Philippines on 23 January 2016Noel Celis/AFP
World Water Day 2017
Women wash their clothes in the Kibera slum in Nairobi on 13 March 2013Noor Khamis/Reuters
World Water Day 2017
A man stands in front of a swamp at a rubbish dump site on the outskirts of Sanaa, Yemen on 16 November 2016Mohamed al-Sayaghi/Reuters
World Water Day 2017
A sofa floats in the polluted waters of Jacarepagua Lagoon, during a press tour in Rio de Janeiro, Brazil on 9 March 2015Ricardo Moraes/Reuters
World Water Day 2017
A resident shows an object contaminated by oil in a coastal area affected by an oil spill near Taiwan's north coast in Shihmen, on 26 March 2016Billy H.C. Kwok/Getty Images
World Water Day 2017
A polluted area caused by an oil spill is seen at the Evrona desert reserve, near the Red Sea resort city of Eilat, Israel on 10 December 2014Baz Ratner/Reuters
World Water Day 2017
Dead fresh water fish known as 'popocha' which turned up at the Cajititlan lagoon in Jalisco State, Mexico on 15 August 2015Hector Guerrero/AFP
World Water Day 2017
A man walks among dead fish lying on a beach in Quang Trach district in the central coastal province of Quang Binh, Taiwan on 20 April 2016AFP/Getty Images

According to the WWD organisation, more than 80% of the wastewater generated by society flows back into the ecosystem without being treated or reused. There are roughly 663 million people who still lack improved drinking water sources. Some 1.8 billion people use a source of 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.

It is mainly in low-income areas of cities and towns within developing countries, that a large proportion of wastewater is discharged directly into the closest surface water drain or informal drainage channel, sometime without or with very little treatment.

World Water Day 2017
A woman washes her yard with contaminated water in the village of Gangnauli in the northern state of Uttar Pradesh, IndiaSajjad Hussain/AFP
World Water Day 2017
An open toilet is seen in a field in Gorba in the eastern Indian state of Chhattisgarh, India on 16 November 2015Adnan Abidi/Reuters
World Water Day 2017
A girl plays with a bucket as she waits to use the only working toilets in the Endlovisi settlement in Khayelitsha township, near Cape Town, South Africa on 14 September 2016Paola Totaro/Reuters
World Water Day 2017
A child washes in a bath of contaminated water in the village of Gangnauli in the northern state of Uttar Pradesh, IndiaSajjad Hussain/AFP
World Water Day 2017
Elena, 11, washes in her home in Santini settlement near Cape Town, South Africa on 11 September 2016. Elena is one of more than a million people in Cape Town with limited access to basic services of water, electricity and sanitationNicky Milne/Reuters
World Water Day 2017
A boy swims in the algae-filled coastline of Qingdao, Shandong province on 15 July 2011China Daily/Reuters
World Water Day 2017
A canal which once carried water from Bellandur Lake to Varthur Lake is filled with toxic foam, emanating from sewage in east Bangalore, India on 1 May 2015. The foam is caused by the polluted sewage water overflowing from nearby Bellandur LakeManjunath Kiran/AFP

In our homes, grey water (relatively clean water that has been used in baths, showers, washing machines and sinks) can be used on our gardens, plants and plots. About a third of household water is used for flushing the toilet; greywater can be collected in a household-scale reuse system and treated to a standard that is suitable for toilet usage. Untreated greywater can be used for garden watering if used immediately after it is produced – soil is effective at filtering out many contaminants in grey water. However, wastewater from kitchen sinks and dishwashers should not usually be collected as it is too heavily contaminated.

In our cities, we can treat and reuse wastewater for green spaces and in our industries and agriculture, we can treat and recycle discharge for things like cooling systems and irrigation. By using this valuable resource, we will make the water cycle work better for every living thing. It is thought that by 2050 nearly 70% of the world's population will live in cities, compared to 50% today, the WWD organisation has stated. At the moment most cities in developing countries do not have adequate infrastructure and resources to address wastewater management in an efficient and sustainable way. Cities will require new approaches to wastewater collection and management.

World Water Day 2017
A worker contracted by the Environmental Protection Agency prepares to set up a turbidity curtain, which prevents sediment and debris from flowing downstream in the Gowanus Canal, Brooklyn, New York City on 24 October 2016. Formerly a bustling transportation and shipping route, the Gowanus Canal is now listed as one of the most polluted bodies of water in the US. In 2010, the Gowanus Canal was declared a Superfund cleanup site by the USEnvironmental Protection AgencyDrew Angerer/Getty Images
World Water Day 2017
A Palestinian man holds a boy on a street flooded with sewage water from a sewage treatment facility in Gaza City November, 2013. Gaza municipality said it could not operate the sewage treatment facility due to shortages in fuel and power on 1 November 2013Mohammed Salem/Reuters
World Water Day 2017
A girl collects drinking water at Dala river outside Yangon, Myanmar on 3 March 2016Soe Zeya Tun/Reuters
World Water Day 2017
Men pour water brought by cart into a container at a stall on Clifton Beach in Karachi, Pakistan on 5 March 2016Akhtar Soomro/Reuters
World Water Day 2017
A boat takes residents across the main banks of the Ciliwung river, while a group of children cast their nets to try to catch fish on 28 December 2016 in Jakarta, Indonesia. Such a scene would have been unthinkable several years ago on the major river, which used to be heavily polluted with stinking rubbish that blanketed the water's surfaceGoh Chair Hin/AFP
World Water Day 2017
A boy draws drinking water from a well using a hand pump in Peshawar, Pakistan on 4 March 2016Fayaz Aziz/Reuters
World Water Day 2017
A boy fills plastic bottles with drinking water from a tap on the outskirts of Islamabad, Pakistan on 22 February 2016Faisal Mahmood/Reuters
World Water Day 2017
A boy, who collects wastepaper for recycling, takes a bath while others wash near a puddle of water at a demolished plot in Karachi, Pakistan on 26 April 2016Akhtar Soomro/Reuters
World Water Day 2017
Residents use a hose for water to wash in the mostly demolished Metro-Mangueira 'favela' community in Rio de Janeiro, Brazil on 12 June 2016Mario Tama/Getty Images
World Water Day 2017
A woman draws water from a well 2 kilometres away from her village, which has no access to fresh water, in Siverek, a town in Sanliurfa province, Turkey on 2 February 2017Sertac Kayar/Reuters

Improved wastewater management can improve the health of workers, especially in agriculture, by reducing the risk of pathogen exposure. It can also create direct and indirect jobs in water-dependent sectors and beyond.

It has been estimated that more than 40,000-60,000 km of land is irrigated with wastewater or polluted water posing health risks to farmers and to eventual consumers of the agricultural products. Available technologies allow removal of almost all contaminants from wastewater, making them suitable for every use. The WHO Guidelines on Safe Use of Wastewater in Agriculture and Aquaculture and the Sanitation Safety Planning (SSP) approach provides a comprehensive framework to ensure that health risks are managed to protect public health. Israel paves the way, where treated wastewater accounts for 50% of irrigation water.

World Water Day 2017
A man pours water on a sheep after fetching it from a well on a farm in Pocoes municipality in Monteiro, Paraiba state, Brazil on 13 February 2017Ueslei Marcelino/Reuters
World Water Day 2017
A pipe releasing waste water into fields surrounding a dairy farm (not pictured) in Gannan county, Heilongjiang province, ChinaNicolas Asfouri/AFP
World Water Day 2017
Pools of wastewater are seen at a sewage treatment plant in town of Safed in northern Israel on 6 October 2013Baz Ratner/Reuters
World Water Day 2017
A sign reading "do not enter" stands in front of a tunnel at the construction site of a new underground pumping station for wastewater in Oberhausen, Germany on 15 August 2016Sascha Schuermann/Getty Images
World Water Day 2017
A man fills up water tanks with recycled water to revive dying plants in his garden, in Burbank, Los Angeles, California, US on 12 September 2015Lucy Nicholson/Reuters
World Water Day 2017
A man waters his garden with recycled water during a drought season in La Paz, Bolivia on 24 November 2016David Mercado/Reuters
World Water Day 2017
Untreated sewage waste falls into the river Ganges in Kanpur, India on 20 May 2016Prakash Singh/AFP

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