Pros

Water with high TDS value, which range from 500 to 2000 ppm;

The foundation is hard or borewell water;

The price varies, according to technology membranes and storage capacity.

Cons

These purifiers need electricity to work;

There is a lot of water wasted throughout the purification process;

RO purifiers cannot kill germs and various other bacteria;

They are expensive to maintain.

UV Purifier

These purifiers take advantage of ultraviolet purification technology in the process. They use UV radiations for killing bacteria, germs and viruses. 

UV water purifiers work by letting the water go through UV Radiations that get rid of germs, clearing it from diseases caused by viruses such as typhoid, dysentery and types of sewage treatment plants cholera. Furthermore, they don't remove dissolved salts - good for your body - and they don't make water naturally acidic, unlike a RO purifier.