day by day population is increasing and water available on earth remains same, in future it will become very difficult to get water on earth
It has been estimated that around 2% of the water is ready for drinking. The remaining 98% is salt or soluble water not prepared for drinking. However, there are technologies that can transform non-drinking water in drinking water, such as nuclear technology, among others. The problem is that the current available technologies are very expensive. For this reason, what we should do is to reduce the cost of the present technologies or to find better ones. We have no choice.
The demand for clean water is increasing day by day. As the water resources are getting more polluted, scientists are inventing new cutting edge technologies to make the water more pure and usable. So, it might be possible that in the near future we will make artificial water reservoir to store the huge amount of purified and treated water.
It is an interesting proposal. It would be very desirable to have such water pumps available for the travelling public instead of plastic water bottles (which are not very healthy anyway). By that time, there will not be gasoline pumps anymore, but electric plug-ins for charging car batteries while you fill your water container with water from the pump. However, it would be a challenge to obtain pure water in the future as it is getting scarce by the day.