SAN FRANCISCO (AP) — As many as 76 million people — mostly children — could die from water-related diseases by 2020 if changes aren’t made worldwide, according to a California think tank.

The United Nations has set a goal of 2015 for cutting in half the number of people who can’t reach or afford safe drinking water. Even if that goal is met, 34 million to 76 million people could die of water-related illnesses, said a report for release Friday by the independent Pacific Institute for Studies in Development, Environment and Security.

More people die of diarrhoeal diseases, such as dysentery, than other water-related diseases, and children are extremely vulnerable to them.

“All of these diseases are associated with our failure to provide clean water,” said Dr Peter Gleick, director of the institute. “I think it’s terribly bleak, especially because we know what needs to be done to prevent these deaths. We’re doing some of it, but the efforts that are being made are not aggressive enough.”

The problem is many people, especially those in developing countries in sub-Saharan Africa and southern Asia, don’t have access to clean water or basic sanitation, Gleick said.

While most of the deaths are projected to occur in developing nations, Joan Rose, professor of water microbiology at the University of South Florida, said every country is vulnerable. She pointed to a recent deadly outbreak of E. coli in Canada that came from a contaminated well.

“We look at our political agreements like NAFTA, and they’ve been economically beneficial to South America because we have allowed them to export their vegetables to the United States,” she said. “But none of that finance has been reinvested in sanitation, and in fact, we may be getting vegetables — we already have — that bring diseases into the United States.”

The United Nations says 1.1 billion people worldwide live without access to safe drinking water and 2.5 billion lack proper sanitation.

The institute will send the report to the World Summit on Sustainable Development being held August 26 through September 4 in Johannesburg, South Africa.