The cost of water

How much water do you need?

Worldwide, some 650 million people are without clean water and more than 2.3 billion people have no access to basic sanitation, says a new report.

The World Health Organization (WHO) recommends 50 liters of water per person per day as the ‘intermediate’ quantity needed to maintain health, hygiene and for all domestic uses.

But how much does 50 liters of water cost?

• Cost In Port Moresby, Papua New Guinea – 50l of water bought from a delivery service:
  £1.84 [54% of typical low daily salary for a snack stall-holder]
  [£1.00 (GBP) = $1.41 (USD) today.]

• In Antananarivo, Madagascar – from a tanker truck:
  £0.50 [45% of typical low daily salary for a factory worker]

• In Accra, Ghana – from a tanker truck:
  £0.45 [25% of typical low daily salary for a street food-seller]

In India it can cost up to a fifth of the daily wage to buy a day’s worth of water!

• In Maputo, Mozambique – from a street vendor:
  £0.09 [13% of typical low daily salary for a street food-seller]

• In London, UK – from an official piped supply:
  £0.07 [0.15% of typical low daily salary for a person on minimum wage]

Source: The State of the World’s Water 2016

WaterAid’s 2016 report

New method for water purification?

Public Release: Uppsala University

Seeds from the Moringa tree can be used for water purification

Pure water is a key requirement for good health and alternative cheap, safe methods are required in many countries. In a paper that has just been published in the leading American Chemical Society journal on interfaces, Langmuir, researchers from Uppsala University in co-operation with The University of Botswana describe how extracts from seeds of the Moringa oleifera tree can be used for water purification.

Moringa oleifera (kalamungay, drumstick tree). Pods and seeds on ground at Dairy Rd Kahului, Maui.  Source: Plants of Hawaii. February 07, 2007. For more images CLICK HERE.

Flocculation of particulate impurities is a common first stage in purification of water. This often uses addition of either aluminium or iron salts. Aluminium, particularly, has undesirable health implications. An alternative procedure that uses a natural extract from seeds of the Moringa oleifera tree is used in Africa.

Research in a paper that has just appeared in the leading American Chemical Society journal on interfaces, Langmuir, describes how very small amounts of the protein from these seeds can bind strongly to surfaces and thus would cause contaminant particles to aggregate. The Scattering Centre at Ångström Laboratory and the Department of Physics and Astronomy at Uppsala University is a centre of expertise in exploiting a powerful technique known as neutron reflection to measure structure and composition of layers of just a few nanometres (millionths of a millimetre) at the interface between a solid and a liquid.

A co-operation with the University of Botswana where there is a long interest in exploiting natural products has led to a research project that provides important insight in to the way that protein molecules from the Moringa oleifera seeds interact, binding stongly both to each other and surfaces so as to cause aggregation in to large lumps that are readily removed from the water.

“It is nice to see how the basic interactions of molecules can play a role in solving practical problems,” says Adrian Rennie, Professor at the Department of Physics and Astronomy at Uppsala University. “Understanding of the process may lead to further development in water purification with materials that are locally available and environmentally friendly.”

Contact: Adrian Rennie
adrian.rennie@fysik.uu.se
Uppsala University