What is the main cause of water scarcity?

I think the main reason is how much water we use. There are so many people now. More people need more water for drinking and daily life. But the biggest use is for our farms. We need lots of water to grow food for everyone. Factories also use a lot of water.

So, the demand is very high. But supply is not enough. We take too much water from the ground. Rain is also not coming like before because weather is changing. And pollution makes good water dirty. So we have less clean water for so many people.