Something momentous, historic and to be celebrated. It's not going to happen for a while. Probably not for another 10 to 15 years, and we may not even know the exact moment or time when it does take place. But it will genuinely change the world, and undeniably for the better.
Within the next 15 years there is the real prospect that everyone, everywhere, will be able to access clean drinking water.
For the first time in human existence no-one will have to go thirsty because of a lack of safe water to drink.
Such a moment, when it comes, should be celebrated and recognised as one more defining achievement of humanity, sitting alongside the elimination of smallpox and the discovery of penicillin.
Over the past 20 years, two billion people have gained access to clean drinking water for the first time. The Millennium Development Goal (MDG) target of halving the proportion of those lacking access to water was met – five years early. This was a considerable achievement, and shows how having a clear, simple target works.
Providing safe drinking water and safe sanitation shouldn't just be seen as an end in itself, but as the first step out of poverty. These basic services transform lives.
Child mortality rates have fallen by five million per year over the past two decades, and improved access to water has played a large part in this.
A new WaterAid report, Everyone Everywhere, released today on World Water Day, shows how every year 700,000 children under the age of five still die needlessly, having developed illnesses linked to unsafe water and poor sanitation.
And, tens of millions of hours could be saved every day by releasing women and children from the burden of collecting water. According to a 2006 survey conducted by Unicef and the World Health Organisation, women and girls do nearly two-thirds of water collection for their families in developing countries. If we free up this time, mothers will be more economically active and children will miss fewer days at school.
Poor sanitation and water cost developing countries 5% of their GDP a year. Taken in context, that is more money than the total African countries receive in aid. The simplicity of it is at times overwhelming, but put another way, if everyone in Africa had access to clean water and safe sanitation it would mean more in increased productivity than the continent currently receives in overseas support.
This is not to say such progress towards getting water and sanitation to everyone will come easily, it never does. While those lacking water are in the hundreds of millions, 2.5 billion people – more than one in three of the world's population – currently lack access to sanitation. Dealing with the challenge of unsafe sanitation must sit alongside a new goal to end thirst.
And the 783m people lacking clean water will be the hardest to reach. They are the poorest of the poor, the most marginalised and dispossessed. Getting access to safe drinking water for them will not be easy, but it is because they currently sit at the bottom of the pile it is all the more important we succeed.
Next week in Indonesia global leaders meet to debate refreshing the MDGs in 2015. To lift the poorest people in the world out of extreme poverty, the post-2015 framework must include measures to prevent and resolve conflicts. And a key catalyst for future conflict could be shortage of natural resources such as water. So this goal of access to clean water for all is not just about health or food or productivity. It will save lives in other ways, by delivering secure access to a basic need and preventing conflicts over that access.
The UK is centre stage in this debate, so the Prime Minister must insist the importance of access to and good governance for natural resources is central to the targets set for worldwide action from 2015.
UK charity WaterAid has for 30 years worked with the world's poor to help them gain access to a basic necessity of life: water. They and others have used the opportunity of World Water Day 2013 to sound a challenge to us all, including the world leaders debating what will come after the Millennium Development Goals end in 2015.
Across the globe, people are engaging: here in Scotland WaterAid supporters will be diving with sharks, climbing mountains, racing with 20kg water carriers (the weight of water that women in Africa and Asia carry on their heads, each day, is commonly 20kgs – the same as the average UK airport luggage allowance).
Throughout sub-Saharan Africa communities will gather to celebrate the transformative impact of clean water. In Mchinji, a rural town in central Malawi, families will gather to learn about local innovations in safe water technologies and celebrate the value of clean, safe water. Together, these small acts show the commitment that water is to the beginning of a better world.
A defining milestone of human achievement is within our grasp. I for one want to be part of the generation that makes sure everyone, absolutely everyone, has access to clean water to drink within the next decade or so. If we pull together we can make it happen.
Lord McConnell is a campaigner on global poverty and an ambassador for the charity Pump Aid.
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