How a simple rain water management system transformed a semi arid village in Rajasthan, India

Israel has grappled with crippling drought for years. But people have learned to use Mediterranean sea water and recycled wastewater to provide the country with enough water for all its needs.

After the drought hit Australia in the early 2000s, city officials had to start thinking seriously about ways to conserve and creatively store their water. External tanks became the solution, storing rain runoff to create an available source of water for Melbourne residents. This solution may not fit every location, but there are other teachable lessons such as taking radically shorter showers.

Laws in Texas and New Mexico, both locked in the grip of a crippling drought, don't do much to actually encourage citizens to conserve water. New conservation laws and financial incentives are trying to change that.

Civic leaders in the U.S. struggle to effectively help their distressed neighborhoods. East Lake, Atlanta, created a replicable model that mixes residents of differing socio-economic status, and focuses on education and health in the area.

In Memphis, a creative blight-reduction initiative called 25 Square Blocks broke down the city into blocks. Inspectors were able to quickly identify all the violations and fix them, using the same amount of funding, but less time, as the old call-and-respond model.

Farmers in Vietnam face rising sea levels but rejected the city's water engineering projects. They prefer gradual measures to cope with climate change so scientists have allowed the farmers to steer the conversation.

Louisiana and Vietnam both need affordable solutions to rising sea levels. Leaders from Vietnam visited Louisiana to compare ideas.

Most insurance companies avoid insuring poor farmers because the transaction costs are too high, but a non-profit in Kenya created a sustainable way to cover them.

Clean water and healthy ecosystems are becoming increasingly difficult to come by. With floating islands and other inventions, eco-entrepreneur Bruce Kania thinks that biomimicry - such as reconstructing wetlands and growing biofilms - can tackle the toughest of water problems.

Ecological toilets that use natural composting to break down waste are simple to construct, waterless and are easy to fix. But as philanthropists are finding, getting these to those that need it most is harder than anticipated.