Why is there a declining amount of drinking water on earth?

There are a few reasons for this. Firstly, and ironically, it is due to global warming. Although sea levels are rising due to the melting of the ice caps, landlocked sea, lakes and rivers are drying up as they are not provided by a large water source. Without these fresh water, people cannot drink it. Water pollution is also contributing a lot. Water is contaminated by waste dumped into these canals and rivers, thus making it unsuitable for drinking. Countries being too poor to build water desalination plants, people wasting water and such are the factors leading the less and less drinking water on Earth.