Overview: Earth is alive because of liquid water and the human story is intimately connected to our relationship with it. But the growth of our civilizations has created a dangerous dependence on a precious resource that may be about to run out.

DVD Verdict: This three-part series explores just how critical water is to our survival and the challenges that are facing us.

Water seems the most renewable of all the Earth’s resources. It falls from the sky as rain, it surrounds us in the oceans that cover nearly three-quarters of the planet’s surface, and in the polar ice caps and mountain glaciers.

It is the source of life on Earth and quite possibly beyond – the discovery of traces of water on Mars aroused excitement because it was the first indication that life may have existed there.

The problem is that most of the Earth’s water resources are as inaccessible as if they were on Mars, and those that are accessible are unevenly distributed across the planet.

Water is hard to transport over long distances, and our needs are growing, both for food and industry. Everything we do requires water, for drinking, washing, growing food, and for industry, construction and manufacturing.

With more than 7.5 billion people on the planet, and the population projected to top 10 billion by 2050, the situation is set to grow more urgent.

Currently, 844 million people – about one in nine of the planet’s population – lack access to clean, affordable water within half an hour of their homes, and every year nearly 300,000 children under five die of diarrhea, linked to dirty water and poor sanitation.

Providing water to those who need it is not only vital to human safety and security, but has huge social and economic benefits too. Children lose out on education and adults on work when they are sick from easily preventable diseases.

Girls in developing countries are worst off, as they frequently stop going to school at puberty because of a lack of sanitation, and girls and women travelling miles to fetch water or forced to defecate in the open are vulnerable to violence.

Providing affordable water saves lives and reduces the burden on healthcare, as well as freeing up economic resources. Every $1 invested in clean water yields at least $4 in economic returns, according to the charity WaterAid.

It would cost just over $21bn a year to 2030, or 0.1% of global GDP, to provide water and hygiene to all those who need it, but the World Bank estimates that the economic benefits would be $60bn a year.

So, the big questions asked here in 'H20: The Molecule That Made Us' is Is climate change making things worse? Well, climate change is bringing droughts and heatwaves across the globe, as well as floods and sea level rises.

Pollution is growing, both of freshwater supplies and underground aquifers. The depletion of those aquifers can also make the remaining water more saline. Fertilizers leaching nitrates into the supplies can also make water unsuitable for drinking or irrigation.

To find out more about how water/H20 is as essential to our living as much as it is to the actual, physical planet we call home, I urge you to buy this wonderful, intriguing and eye opening new DVD from PBS. This is a Widescreen Presentation (1.78:1) enhanced for 16x9 TVs.