New study shows global shortage of clean drinking water is more serious than previously thought

In 2021, the World Health Organization (WHO) and the United Nations Children’s Fund (UNICEF) estimated 2 billion people Clean water is scarce all over the world.

About a quarter of the world’s population might have been bad enough. But on Thursday, New research published exist science Two billion is a huge underestimate. The new analysis shows that 4.4 billion people in low- and middle-income countries, more than half the world’s population, do not have safe drinking water at home. It’s not that billions more people are losing access to water. Rather, the way researchers measure water has become more accurate, and these new measurements suggest the problem is much worse than previously thought.

If you’ve always had clean running water at home, it’s easy to forget that much of the planet doesn’t have access to drinkable tap water.

In developed countries like the United States that have sanitation systems, water is pumped from lakes, rivers or underground reservoirs and sent through treatment plants to filter out dirt, bacteria and harmful chemicals. The water is then stored in places like water towers and piped to homes. If everything goes well, the water is safe to drink.

Even so, the process is not 100% correct. Leaky pipes, Aging infrastructureand Chemical pollution Access to safe drinking water can be limited even in the wealthiest countries. If this is a logistical hurdle for countries with clean, cheap and plentiful water, the burden of providing safe drinking water for all is even greater in low- and middle-income countries, especially in rural areas where limited sanitation infrastructure, conflict and insufficient funding can prevent access.

Access to sufficient, clean, reliable and affordable drinking water is a human right. The United Nations urges Governments invest resources in building and maintaining water infrastructure. (United Nations Sustainable Development Goals Better funding is essential, but unless money is directed strategically to the right places and projects, throwing money at the problem It may not solve the problem. This is where the new data comes in.

Esther GreenwoodPhD student at ETH Zurich, Swiss Institute of Aquatic Sciences Eawagnoticed that there were huge gaps in information about drinking water services for more than half of the world’s population. By filling these gaps, Greenwood and Lead Researcher Tim Julian Aims to highlight areas where investment in drinking water testing is most needed.

“The fact that so many people in the world do not have reasonable access to safe drinking water must be a cause for deep reflection.” Martin Ackermann “This could have been avoided,” he said.

Counting how many people have access to safe drinking water is not easy, especially in rural areas, where this data is most important. Historically, UNICEF has relied on Household SurveyTeams are sent out to conduct on-site interviews with a sample of households in a particular country. They ask Questions like these, “Can you provide me with a glass of water that your family usually drinks?” and “Where is this water collected from?” – all of which can clearly reflect a household’s current water use situation.

However, these surveys are labor-intensive and costly, so information is collected only every 5 to 10 years. Any factors that affect water use over shorter time periods are likely to be Animal Husbandry arrive Seasonal variation in rainfallwill not be caught. Until recently, investigations No question about water quality Greenwood added that for most regions, there is only one survey data on drinking water contamination, making it difficult to assess trends over time.

Greenwood’s team combined 39 different sources of geospatial data for the study, from land and satellite sources, in addition to survey data from more than 64,000 households in 27 countries between 2016 and 2020. They used all this information to train Machine Learning Models Assess whether the water in a region meets Four safety standards Data from the WHO/UNICEF Joint Monitoring Programme (JMP), which collects data on water supply, sanitation and hygiene: whether it is improved (for example, from a safe source such as pipes, rather than unprotected wells) and whether it is available when needed, can be reached without commuting, and is free from faecal contamination.

In the past, water quality was measured by averaging survey results for a country’s entire population. Greenwood said the JMT typically tries to average all the water safety standard-related survey results and then highlights the lowest values. If a survey in a country finds that 80% of people get water from an improved source, 50% have water at home, 40% have continuous access to water, and 30% have clean, uncontaminated water — the JMT would report that 30% have safe drinking water.

This erases a lot of the nuance of people’s personal experiences. What if you have access to clean water, but you have to walk three miles to a kiosk to get it? Or what if you have steady access to water at home, but Delivered to tanks via weekly trucks (“unimproved” water sources)?

To address this, Greenwood’s team instead calculated data at the household level and divided the land into smaller plots than in mature countries to create more accurate maps of safe drinking water access. They found that in 2020, two-thirds of people living in low- and middle-income countries did not have access to safe drinking water at home.

Fecal contaminationE. coli infection was the biggest problem for nearly half of the subjects studied. E. coli can appear in drinking water downstream when people or animals defecate near a water source, or when sewage is not properly treated. Drinking this contaminated water can cause diarrhea—an annoyance for adults but a massive killer for young people, More than 1,000 children die from the disease every daymainly distributed in South Asia and sub-Saharan Africa.

While the technology needed to measure E. coli levels is widely available, actually collecting drinking water samples and testing them is expensive, especially in remote rural areas. As a result, Greenwood said, “we still lack national data on drinking water contamination for about half of the world’s population.” Other chemicals, such as arsenic and pesticide Bacteria can also cause health problems when they get into drinking water, but data on these contaminants is even more limited than on E. coli—so limited that Greenwood’s team couldn’t include them in its training data.

Greenwood’s team found that environmental factors such as tree density and seasonal variations in rainfall were another major predictor of drinking water quality. This is consistent with what researchers already know – that water quality is affected in part by the weather.

For example, runoff after a heavy rainstorm can pick up bacteria, dirt, and pollutants as it flows back into rivers and lakes. Heatwave It is also linked to a surge in water pollution, especially in low-income regions. This will become an increasingly pressing issue as the planet continues to warm—low-income countries that currently face water insecurity It is also the most vulnerable The impact of climate change.

Landscape and urban development also play a role. Sometimes water is scarce because humans built a city in an arid place, or because the city’s water supply is low. Cape Town, South Africa Almost forced to cut off water supply In 2018, after years of drought, Kenya narrowly averted a large-scale crisis through measures to restrict water supply and reduce demand.

But often the problem isn’t the quantity of water, but the quality of the water and how much is available to households. Wastewater treatment plants are often poorly managedor Insufficient water pressure This resulted in the water service being unable to continue to operate. Mexico CityFor example, due to climate change and human mismanagement, cities may also face the situation of running out of water in the near future. When the city pipes run dry, people will choose bottled water or pavilion Usually available, but these can Costs up to 52 times.

Addressing big policy issues like water scarcity requires a lot of data. Greenwood’s team is starting to fill in some of the gaps left by the Joint Monitoring Program, but she says the information they really need — frequent, hyper-local measurements of water use over time — still doesn’t exist. This longitudinal data is especially important for understanding how climate change affects drinking water services. Because climate and weather fluctuate faster than a once-a-decade survey can capture, surveys alone are not enough.

Household data also doesn’t necessarily reflect a person’s daily water use. People also drink water and go to the toilet at work, in schools and other public places – and there are still huge gaps in information about drinking water. Public waterThis study also did not address Affordability of drinking wateror disproportionate The burden of water scarcity on women When there is no water at home, you often have to go out to fetch water.

While the geospatial data Greenwood’s team uses can’t necessarily answer those questions, it can help direct resources in the right direction. Areas with particularly high levels of fecal contamination, or densely populated areas with limited water sources, might be prioritized by governments.

Greenwood hopes that by demonstrating the dramatic impact that geospatial information can have on water security estimates, their team can mobilize policymakers to “improve global water quality monitoring, particularly in regions where data gaps currently exist.”