Estimating clean water availability seems surprisingly difficult given lack of coordinated national data collection.
"...surveys are labor-intensive and expensive, so information is only gathered once every five to 10 years. Anything that affects water use at a shorter timescale, from livestock farming to seasonal changes in rainfall, won’t be captured. And until recently, surveys didn’t ask about water quality at all, Greenwood added. For most regions, only one survey’s worth of data on drinking water contamination exists so far, which makes it difficult to assess trends over time.
Greenwood’s team incorporated 39 different sources of geospatial data in their study, gathered on land and via satellite, in addition to survey data from over 64,000 households across 27 countries between 2016 and 2020. They used all of this information to train machine learning models to estimate whether the water in a given place met four safety criteria from the WHO/UNICEF Joint Monitoring Programme (JMP), which collects data on water supply, sanitation, and hygiene: improved (as in, from a source that could be safe, like pipes, rather than an unprotected well), and whether it was available when needed, accessible without a commute, and free from fecal contamination."
Thanks that's an interesting statistic actually.
I'm not sure this is the most useful measure though - number of people drinking clean water is a more direct indication of infection risk. In Uganda where I live maybe 80ish percent of people don't have access to clean drinking water at home but I would guess over half the population drinks clean water which they walk to get. (stats findable but can't be bothered right now).
I think they were trying to explain this here but I didn't understand what they were getting at
"This washes out a lot of the nuances of people’s individual experiences. What if you have access to clean water, but you have to walk to a kiosk three miles away to get it? Or have consistent water access at home, but it’s piped into tanks via weekly truck deliveries (an “unimproved” water source)?
To get around this problem, Greenwood’s team instead calculated data at the household level, and divided land into smaller chunks than full-blown countries to create a more accurate map of safe drinking water use. They found that two-thirds of people living in low- and middle-income countries had no household access to safe drinking water in 2020."
This seems like like an economically important measure (time wasted walking,) rather than a health measure directly. What you are drinking is what matters health wise, not whether you have it at your home or not.