You can live for three to five days without water. But if you don’t drink after that, your organs begin to shut down and you can die.
If you have water, but it’s dirty, you’ll get ill. The water will make you sick and you’ll get diarrhoea. And then it doesn’t matter if you eat healthy food, you’re losing it all and are then faced with the risk of life-threatening hunger.
When that happens, it doesn’t matter how much water you drink, you’re at risk of dying of thirst because your body needs to get rid of all the infected water and you dehydrate rapidly.
So, before anything else, every human needs to have a safe and reliable source of water. Forget housing, medicine, schools, work… Without water, none of that matters.
But water is becoming more and more scarce.