There are small water purifiers that run without electricity too.
Tata Swach has such overhead tank type purifiers. Buy and keep the cartridge just in case service is horrible in your area. If you want powered one PureIt has 5-10l storage purifiets. Search on FlipKart or Amazon.
There are units that you can connect to the tap, fill your bottle and remove it. They do a pretty good job. You won't get uv or osmosis type filtration but it's better than drinking normal water.