Just Imagine you could produce water out of thin air with no connection to any mains utility. Sounds incredible, especially if it operates where the air is very dry like deserts and steppe regions of the world. Such a device has actually been designed and the best thing about it is it uses almost no mechanical parts or complex electronics and works purely from the effects of direct solar radiation (not PV cells).

Researchers at MIT have been using a structure known as a Metal Organic Framework (MOF) to harvest water directly from the air (at humidity levels as low as 20%). This humidity level is commonly found in dry regions of the world. The prototype was able to extract 2.8 liters of water per day at an air humidity of 20 to 30%. Read more

For plenty of people, getting a drink of water on the hottest of days is not as easy as filling a glass at the tap. Instead, they walk miles to the nearest well. Or they pay big fractions of their incomes — more than the average person in a developed country pays — to have a distributor truck in water, which may not even be clean.

Only 42 percent of Nigerians have access to drinking water. The rest of the population must go directly to the source in rivers or natural storm-water reserves, which could be purified by the Slingshot

About one in six people, as of 2005, couldn’t access clean water. But no one can live without water, so it’s often that people without access to a clean water supply end up drinking water laced with chemicals or populated by disease-causing organisms, which can kill children and shorten adults’ lives.

With this in mind, it’s easy to see why the World Health Organization put access to safe drinking water on its list of Millennium Development Goals, or targets to meet by 2015. But can it be done? Each pocket of people suffering water stress needs an affordable method that fits the local conditions and lifestyle.

Chlorine tablets and clay pots, boiling and cloth filters, sun barrels and rain barrels, and filter-equipped straws that can be worn on a necklace have all been tried, but some people still lack a method that works for them. Read more

Until recently, many cities had no legal distinction between gray and black water, rendering most domestic reclamation efforts technically illegal. But due to increased concerns over droughts and water shortages, some residents and local leaders are pushing for updated laws to allow the regulated use of gray water reclamation.

Would widespread gray water reclamation help or hinder sewage treatment plants such as this one in Santiago, Chili? Some say that without gray water to move waste along, sewage might not make it all the way to the treatment facility.

And where there’s demand, industry can’t be far behind. Companies are now offering gray water systems, pre-construction consultation and custom installation, in addition to working on new technologies.

Still, a gray water reclamation system that is legal in one city may be deemed a health hazard in another. Some regions still classify gray water as sewage, while others provide residents with basic health and safety guides for reusing gray water.

Across the globe, the scope of gray water reclamation varies greatly. Australia and New Zealandhave been ahead of the game for years, providing the local regulations, guidance and education needed for residents to make the most of their waste water. Mexico has begun using treated gray water for irrigation. However, in some less-developed nations, things are less encouraging. While gray water reclamation may not be prohibited by law in poorer nations, often there are far worse substances than soap suds draining into the soil. Ironically, the strict laws gray water advocates are fighting to overcome in developed nations were originally instituted to protect the environment and public health. Read more

While the particulars of a gray water diversion or filtration system can vary greatly, several basic steps are commonly used.

A hand-activated valve serves as an important first step in many systems, especially the more basic diversion systems. This valve allows a person to decide when water from a bathroom sink, tub or washing machine will be diverted to the garden and when it will go into the sewage system or septic tank. This level of regulation comes in handy to avoid overwatering during times of heavy rain or sending harmful chemicals or diaper water out to the garden.

After gray water is diverted down a system of pipes, its first stop on its trip to the garden is a basic filter — generally a mesh screen — to eliminate larger particles, before entry into a surge tank. The surge tank is used to help regulate flow by temporarily storing large amounts of gray water. This helps ensure a bathtub’s worth of drainage doesn’t all rush into the garden at once, while also preventing it from backing up into the home. Read more

Most methods of gray water reclamation, from lugging around a full bucket to diverting the water through a costly treatment system, involve a simple cycle:

1. White water is pumped into the home and is used in showers, bathtubs, sinks, dishwashers, laundry rooms and toilets.
2. White water that comes into contact with human waste becomes black water; the rest becomes reusable gray water.
3. Gray water is reused for domestic purposes when appropriate. Black water is sent into a septic tank or sewage system, along with any unused gray water.

Gray water reclamation doesn’t have to be difficult. It can be as easy as taking a bucket with you into the shower.

When pipes are used to divert gray water, take care to prevent pumps and filters from clogging with bits of hair, skin and food. When clogs do occur, it is worth remembering that chemical clog removers are just the kind of harsh chemicals you don’t want to send directly into your garden. Natural solutions, such as boiling water or vinegar and baking soda treatments, might be less damaging to plant life. Additional safety precautions often depend on the specifics of the reclamation system in place, desired vegetation and the home’s residents. Gray water laws also vary from place to place. This issue will be discussed later.

Three basic gray water reclamation systems are commonly used. The main differences involve the scope, complexity and cost of the reclamation process. Read more