Key points
- Diarrhoeal disease is the third leading cause of death in children aged 1–59 months; about 443,832 children under five die each year (WHO, 7 March 2024).
- In 2024, 58% of the global population (4.8 billion people) used a safely managed sanitation service; 3.4 billion people still lacked one (WHO, 5 November 2026).
- Better water, sanitation and hygiene could have prevented an estimated 395,000 deaths among children under five in 2019 (WHO).
- 1.4 million people die each year from inadequate drinking-water, sanitation and hygiene, including nearly 400,000 children under five (WHO/UNICEF).
Direct answer: Dirty water kills children. Diarrhoeal disease is the third leading cause of death in children aged 1–59 months: about 443,832 children under five die each year, and there are nearly 1.7 billion cases of childhood diarrhoeal disease a year (WHO, fact sheet 7 March 2024). A significant proportion can be prevented through safe drinking-water and adequate sanitation and hygiene. In 2024, 58% of the global population used a safely managed sanitation service — and 3.4 billion people still lacked one (WHO, 5 November 2026).
Diarrhoea, in numbers
The figures are WHO’s, from the diarrhoeal disease fact sheet published 7 March 2024. Diarrhoeal disease is the third leading cause of death in children aged 1–59 months. About 443,832 children under five and 50,851 children aged 5–9 die each year, and there are nearly 1.7 billion cases of childhood diarrhoeal disease a year. Diarrhoea is a leading cause of malnutrition in children under five. The fact sheet is the oldest core source in this batch — dated 7 March 2024 — and it is re-checked at each review; the figures on this page are the ones it currently carries.
How many people lack safe water and sanitation
The gaps are measured by the WHO/UNICEF Joint Monitoring Programme (JMP), whose 2025 report covers 2000–2024. In 2024, 58% of the global population (4.8 billion people) used a safely managed sanitation service (WHO, sanitation fact sheet, 5 November 2026). Since 2015, 1.2 billion people have gained access to safely managed sanitation. But 3.4 billion people still lacked safely managed sanitation in 2024, including 1.9 billion using basic services, 560 million using limited services, 555 million using unimproved facilities, and 354 million practising open defecation. For drinking water, 2.1 billion people lack safely managed services. The site’s guide on what WASH is explains the JMP service ladder — safely managed, basic, limited, unimproved, open defecation — in full.
What better WASH could prevent
According to the latest WHO burden-of-disease estimates, 1.4 million people die each year as a result of inadequate drinking-water, sanitation and hygiene, the vast majority in low- and middle-income countries. Unsafe sanitation accounts for 564,000 of these deaths, largely from diarrhoeal disease. Better water, sanitation and hygiene could have prevented an estimated 395,000 deaths among children under five in 2019 (WHO). Poor sanitation is also linked to transmission of cholera and dysentery, typhoid, intestinal worm infections and polio; it exacerbates stunting and contributes to the spread of antimicrobial resistance. The link is not only about germs: poor sanitation reduces well-being through anxiety, risk of sexual assault, and lost opportunities for education and work.
Hygiene and handwashing
Handwashing is the smallest part of WASH and the most often named: 1.7 billion people still lacked basic hygiene services in 2024 (UNICEF Data). The site’s WASH tool carries the handwashing detail — 20 seconds of scrubbing, the CDC’s stated time — and the guide on what WASH is explains the hygiene rung of the ladder. This page states the population figures and goes no further into hygiene practice: how any household washes hands is practical advice, and this site does not publish practical advice. What the figures say is that the gap is not only pipes and toilets; it is also the basin, the soap and the water to use them with.
WASH in schools: out of scope here
One gap is deliberately left open. UNICEF covers WASH in schools, and the WHO sanitation fact sheet notes that separate sanitary facilities particularly boost girls’ school attendance — but this page is household and child-health WASH only, and WASH in schools is a candidate for a later page, not a silent addition here. The same applies to menstrual health, which the research behind this page flagged as out of scope. A page that tried to cover household WASH, school WASH and menstrual health in one place would do none of them properly.
Frequently asked questions
How many children die from diarrhoea each year?
About 443,832 children under five die each year, and diarrhoeal disease is the third leading cause of death in children aged 1–59 months (WHO).
How many people lack safely managed sanitation?
3.4 billion people in 2024, including 354 million people practising open defecation (WHO, 5 November 2026).
Can better water and sanitation save children's lives?
Yes, at population level: better water, sanitation and hygiene could have prevented an estimated 395,000 under-five deaths in 2019 (WHO).