Some 26% of the world’s population do not have access to safe drinking water and 46% lack access to basic sanitation, a new report launched on the eve of the first major UN conference on water in over 45 years has said.

The UN World Water Development Report 2023 painted a stark picture of the gap that needed to be filled to meet the organisation’s goals to ensure all people have access to clean water and sanitation by 2030.

Richard Connor, editor-in-chief of the report, told a news conference that the estimated cost of meeting the goals was somewhere between 600 billion US dollars and one trillion US dollars a year.

But equally important, Mr Connor said, was forging partnerships with investors, financiers, governments and climate change communities to ensure that money was invested in ways to sustain the environment and provide potable water to the two billion people who did not have it and sanitation to the 3.6 million in need.

According to the report, water use has been increasing globally by roughly 1% per year over the last 40 years “and is expected to grow at a similar rate through to 2050, driven by a combination of population growth, socio-economic development and changing consumption patterns”.

Mr Connor said that actual increase in demand was happening in developing countries and emerging economies where it was driven by industrial growth and especially the rapid increase in the population of cities. It was in these urban areas “that you’re having a real big increase in demand”, he said.

With agriculture using 70% of all water globally, Mr Connor said, irrigation for crops had to be more efficient — as it was in some countries that now use drip irrigation, which saves water. “That allows water to be available to cities,” he said.

As a result of climate change, the report said, “seasonal water scarcity will increase in regions where it is currently abundant — such as Central Africa, East Asia and parts of South America — and worsen in regions where water is already in short supply, such as the Middle East and the Sahara in Africa.”

On average, “10% of the global population lives in countries with high or critical water stress” and up to 3.5 billion people live under conditions of water stress at least one month a year, the report issued by UNESCO, the UN Educational, Scientific and Cultural Organisation, said.

Since 2000, floods in the tropics had quadrupled, while floods in the north mid-latitudes had increased 2.5-fold, the report said.

Trends in droughts were more difficult to establish, it said, “although an increase in intensity or frequency of droughts and ‘heat extremes’ can be expected in most regions as a direct result of climate change”.

As for water pollution, Mr Connor said the biggest source of pollution was untreated wastewater.

“Globally, 80% of wastewater is released to the environment without any treatment,” he said. “And in many developing countries it’s pretty much 99%.”

These and other issues including protecting aquatic ecosystems, improving management of water resources, increasing water reuse and promoting co-operation across borders on water use would be discussed during the three-day UN Water Conference co-chaired by King Willem-Alexander of the Netherlands and Tajikistan’s president Emomali Rahmon opening on Wednesday.

There are 171 countries, including over 100 ministers, on the speakers list along with more than 20 organisations. The meeting will also include five “interactive dialogues” and dozens of side events.