Water and health: how access to clean water reduces childhood illness

It is one of the most direct links in all of global public health: the water a child drinks largely decides their chances of survival. Not in some abstract way, but through precise, well-documented biological mechanisms. Once you understand how water kills, you understand why a well saves lives.

Which diseases does unsafe water spread?

Contaminated water isn't simply 'dirty': it carries a whole family of diseases. According to the WHO, microbial contamination of drinking water can transmit diarrhoea, cholera, dysentery, typhoid fever and polio.

The mechanism is almost always the same, and it matters to understand it: human or animal faeces contaminate the water source. The pathogens they carry are swallowed when people drink or cook. They then attack the digestive system.

That is why surface water from an open pond or river is so dangerous: nothing shields it from run-off, livestock or open defecation. A drilled well, by contrast, reaches down to groundwater that is naturally protected.

Why are children the first victims?

Around 1,000 children under five die every day worldwide from causes linked to unsafe water, lack of sanitation and poor hygiene. This figure, put forward by the WHO and UNICEF, deserves a closer look at the reasons behind it.

Three factors explain why young children are so heavily exposed.

1. An immature immune system. An adult can cope with a bacterial load that would floor a two-year-old. Their defences simply haven't developed yet.

2. Rapid dehydration. This is the crucial point. It isn't diarrhoea itself that kills, but the fluid loss it causes. A small body can become dehydrated within hours, whereas an adult will hold out for several days.

3. Maximum exposure. Children play on the ground, put their hands in their mouths and drink whatever water is to hand without a second thought.

The result: according to the World Bank, around 446,000 children under five die from diarrhoea every year, which accounts for 9% of all child deaths worldwide.

The vicious circle of water, diarrhoea and malnutrition

This is the mechanism the public knows least about, yet it is one of the most destructive. We tend to think of diarrhoea as a passing episode. In reality, in a young child, every bout leaves a lasting mark.

According to the WHO, in low-income countries children under three suffer on average three bouts of diarrhoea a year. And each one deprives them of the nutrients they need to grow.

The cycle then takes hold: contaminated water causes diarrhoea, diarrhoea prevents nutrients from being absorbed, undernutrition weakens the immune system, and the weakened child falls ill more easily the next time they come into contact with contaminated water. Each turn of the wheel leaves them more vulnerable.

This explains something that often baffles people: in some regions, food can be distributed without malnutrition going down, simply because the problem isn't only how much food is eaten, but the body's inability to absorb it. Without clean water, nutrition can't keep up.

The 3 levers that reduce childhood illness

The good news is that these diseases are preventable. According to UNICEF and the WHO, 88% of deaths from diarrhoea worldwide are attributable to unsafe water, inadequate sanitation and poor hygiene. In other words, by acting on these three levers, we remove the vast majority of the problem.

1. Water protected at the source. This is what a drilled well does: it reaches groundwater sheltered from surface contamination, instead of drawing from a pond exposed to run-off and livestock.

2. Proper sanitation. Without latrines, faeces find their way back into water sources and the cycle starts again. That is why water and sanitation go hand in hand. Our article Sanitation and hygiene: the water-health-education trio explores this further.

3. Hygiene, above all handwashing. It is the most cost-effective habit in all of public health: according to UNICEF and the WHO, handwashing with soap reduces diarrhoeal disease by more than 40%. But you need water to wash your hands, which brings us back to point 1.

These three levers only work together. Clean water without latrines, or latrines without water for handwashing, is not enough to break the cycle.

What a well really changes in a village

When a village gains access to protected water, the health benefits come quickly. Bouts of diarrhoea become rarer, children can finally absorb their nutrients, doctor's visits and medical costs fall, and the youngest start growing again.

The impact goes beyond health. A child who is no longer constantly ill can go to school. A mother who no longer spends her days nursing sick children or fetching water can work. A village that spends less on healthcare can invest elsewhere.

This thinking shapes LIFE's water programme. A village well, dug to around 20 metres and fitted with a pump, serves around 500 people, and its specifications include laboratory testing to confirm the water is safe to drink before anyone uses it. Funding one costs €2,650 in Africa, or around €901 after 66% French tax relief. To follow the whole process step by step, our article Building a well in Africa: stages, costs and real impact covers every phase.