With rising urban populations and ever-scarcer water supplies, cities and companies are teaming up to invest billions of dollars in water management projects, a report said on Tuesday.

Around two-thirds of cities from London to Los Angeles are working with the private sector to address water and climate change stresses with 80 cities seeking $9.5 billion of investment for water projects, according to a report by the Carbon Disclosure Project (CDP), a non-profit environmental research group.

Water investment opportunities are greatest in Latin America, with Quito in Ecuador seeking $800 million to manage its water supply, including building three hydropower stations and cleaning up its contaminated rivers and streams.

The cities most concerned about their water supply lie in Asia and the Pacific, the report found, with serious risks also identified in Africa and Latin America.

The key issues for cities include declining water quality, water shortages, and flooding.

The Indian city of Chennai faced extreme floods in 2015 which killed hundreds and left survivors without access to clean water, while businesses were also severely disrupted.

The city is now investing in boosting its resilience to future water crises, with water conservation education, building a storm water management system, and new infrastructure.

"We are seeing critical shifts in leadership from cities and companies in response to the very real threat of flooding, for example, to local economies," said Morgan Gillespy, head of CDP's Water Program.

Climate change is another underlying threat to all cities with an increase in extreme weather events from droughts to floods, with cities in North America more concerned than those in Europe, the report found.

Tropical Storm Harvey, pounding the US Gulf Coast, has killed at least eight people, led to mass evacuations, and paralyzed Houston, the fourth most-populous US city.

The storm is most likely linked to climate change, said the UN weather agency.

Companies are also concerned about the effects of climate change on water supplies, with $14 billion of water impacts such as loss of production reported by companies last year, the report found.

The United Nations predicts a 40 percent shortfall in global water supply by 2030, while global demand is set to increase by 55 percent due to growing domestic use, manufacturing, and electricity generation.

"From our work with cities around the world, water has consistently come up as a key resilience challenge," said Claire Bonham-Carter, Principal and City Resilience Lead at AECOM, a global infrastructure firm and partner on the report.

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"Many of them, regardless of size, from Mexico City, Mexico to Berkeley, California, are addressing both long-term water supply issues as well as chronic urban flooding."

This story was reported by Reuters.