By Mark Kinver
BBC News science and nature reporter
Water policies are failing to deliver adequate access to clean drinking water to millions of people around the world.
Are arguments over funding eclipsing possible solutions?
That was the stark message that emerged from the latest edition of the influential UN World Water Report.
The publication of the report coincides with the start of the 4th World Water Forum in Mexico City.
The gathering attracts delegates from all over the globe who will debate the key water issues facing the world.
The UN's report warns that if there is not a marked improvement in existing measures, the Millennium Development Goal of halving the proportion of people without access to safe drinking water between 1990 and 2015 will be missed.
So who is to blame for the failure of current approaches?
The Sustainable Development Network, a coalition of 30 free-market non-governmental organisations (NGOs), firmly points the finger of blame at governments.
The Network says heavy-handed regulation is hindering rather than helping the situation.
Pushing the limits
It has published a book listing a series of examples from all over the world where, it says, market forces are delivering the clean water that governments have failed to provide.
The editor of the book, Kendra Okonski, a director of the UK-based International Policy Network, says the solution is to give water a market value.
"If we view water as a global common good, it means that we collectively own it and no one has the responsibility to look after it.
"But if we manage it with markets and underlying institutions - such as property rights and the rule of law - then people are much more likely to look after the water and use it more effectively," she told the BBC News website.
One region where governments are failing is Africa, Ms Okonski says, where many countries are experiencing rapid rates of urbanisation.
"You have some of the poorest people on the planet moving to cities, to live where the slums or shanty towns are located. But national and local governments refuse to extend the boundaries of the cities.
"These cities' water systems are not being extended because the governments are refusing to recognise the land tenure of these people."
She says this has led to many small-scale entrepreneurs providing water all over these cities in a number of ways.
"What they do is meet a demand, so in a way you do have markets operating in these regions. That is not to say it is satisfactory, but it is an example of people providing services where governments are not."
Barun Mitra, director of the Delhi-based Liberty Institute, agrees: "It is the inability to learn from the bottom up that is at the root of this problem."
He gives an example of an "informal entrepreneur" providing water to people in the poorest area of the Indian capital.
"This entrepreneur has connected up a number of dwellings in the slum by a grid of pipes. He then provides water for half an hour in the morning and another half an hour in the evening.
"People pay about $10 a month for this," Mr Mitra told this website. "Where the monthly income will be $100 or less, this is a lot of money but people are willing to pay because they will have a secure supply of water.
"But because the entrepreneur is also from the same area he can judge people's ability to pay on a case-by-case basis. It is an extremely flexible way of providing water."
Mr Mitra said public officials should recognise the role these entrepreneurs were playing in providing a service and see them as a source of revenue that would otherwise be lost.
"This entrepreneur should be used by the utilities in this area, rather than being branded illegal."
Private sector 'myth'
But not everyone backs the view that the private sector can deliver a framework that will put the Millennium Development Goal back on target.
The World Development Movement will publish a report next week that will coincide with World Water Day (22 March). It will say efforts to privatise water supplies in developing nations have failed.
Peter Hardstaff, head of policy at the UK-based campaigning organisation, says the key question is about funding.
"If you look at the estimates of what is needed, you are looking at tens of billions of dollars to invest in improving access to water and sanitation for the world's poorest people.
"Our report demonstrates that the private sector is not going to come up with the money because they do not have that sort of money," he told the BBC News website.
WORLD WATER FACTS
One billion people without access to clean drinking water
2.6 billion without adequate sanitation
Rapid urbanisation increasing pressure on water resources
30-40% of water 'lost' through illegal tapping and leaks
(Source: UN World Water Report)
"We have got to move away from this myth that the private sector is going to come up with the cash."
Mr Hardstaff said there were many arguments about the best way to invest public money in order to deliver results.
"What has been shown to work across the world, both in developing and developed nations, is public utilities. There are community-owned and managed schemes, workers' co-operatives - there are whole different ways of doing things.
"But the past 15 years of experience suggests that the private sector does not have the money and is no more efficient or effective than the public sector.
"So if we are going to spend public money and we need strong government, let's accept that fact and get on with improving things."
Carlos Fernandez-Jauregui, deputy co-ordinator of the UN's World Water Assessment Programme, sets the context of why there is a need to find a way to deliver results.
"If we continue business as usual the water crisis will get worse - not only in developing countries but also in developed countries," he told these pages when the UN World Water Report was published.
"We ignore this at our peril."