by Kevin Rudd, originally published on March 22, 2016

More than 800 children die each day from diarrhoea. About 663 million people still use water contaminated by human waste and other pollutants. And roughly 2.4 billion people still lack access to a basic toilet. Open defecation presents a major, avoidable public health hazard. Women and girls living in communities that lack basic facilities live in fear of sexual assault, because they need to go outside to go to the toilet.

Women and girls are also affected in other ways by water access. Often tasked with finding water for their families, they act almost as beasts of burden, carrying water vast distances. Collectively, women and girls spend roughly 125m hours a day fetching water. The absence of basic menstrual sanitation also means millions of girls are absent from school for up to a quarter of the academic year.

Many people are uncomfortable even talking about these issues. We need to overcome this.

As the recent multilateral meeting of the global partnership on Sanitation and Water for All in Addis Ababa reminded us, the cost of building the infrastructure to deal with the problem can be prohibitive. The World Health Organisation calculates it is $11.3bn (£7.9bn) a year beyond current investments. But this presents an insuperable problem only if we see public finance – through national governments, international development banks and national development agencies – as the only source of capital.

There is also a critical role for domestic private finance and international private investment, although creating such financial partnerships can be difficult. Businesses require monetary returns on their investments; projects must be “bankable.”

Access to clean water and basic sanitation is a human right and a public good. But those declarations alone do not solve the financing problem. Water and sanitation services must therefore be paid for, with tariffs adjusted according to the ability of local communities and individuals to pay. For the poorest of poor communities, this will mean zero tariffs or simple public water provision until social and economic conditions improve.

A new generation of public-private partnerships (PPPs) is helping the response to these challenges.

Such partnerships are sometimes deeply flawed, failing to balance financing and social needs effectively, and this has given them a bad name. But the answer lies in the legal and financial design of each contract: from the smallest, village-level agreements to larger, nationwide projects.

Partnerships involving small-scale private operators are growing in developing countries, partly through donor-sponsored PPP projects for water and sanitation. As these projects are implemented and scaled up, they engage new local operators who take them forward as external support fades. Such partnerships are enjoying success from Latin America to Africa and beyond.

We must now begin to do this at scale. Suggestions on filling the global funding gap for water, sanitation and hygiene, not least in the critical area of faecal sludge management, should be welcomed.

The principle is clear: no money, no progress. Without finance, the sustainable development goals agreed by UN member states in September are just laudable normative statements of what the world should look like, lacking the means to make it that way.

The social, economic and business case for a quantum change in investment patterns in water, sanitation and hygiene is clear. The World Health Organisation calculates that every $1 invested in water and sanitation has a return of at least $4 in lower health costs, more productivity and fewer premature deaths. Yet the sector has arguably been the slowest to adapt to the harsh new financial world in which we live, where the constraints of domestic public finance and foreign aid are becoming sharper each year.