RO water purifiers use a semipermeable membrane to purify water. All the dissolved solids like fluoride, other harmful chemicals, and heavy metals got stuck in the RO membrane and making the water safe for consumption.
RO requires electricity and running water. Also, it converts hard water into soft water.
UV water purifiers use ultraviolet (UV) rays for the purification of water. It kills water-borne disease and removes the virus & harmful germs but doesn't remove chemicals like fluoride, chlorine present in water.
UV requires electricity and running water but doesn't convert hard water into soft water as RO does.
Commonly people don't have an idea about RO Vs UV, Which Water Purifier is better for health.
Gravity-based purifiers use pressure filtration to purify water. The filters are comprised of sediment or sediment with activated carbon that removes most of the germs & bacteria, undissolved impurities, chemicals, and microorganisms.
This purifier doesn't require electricity and running water. Gravity-based water purifiers are suitable only for places where the TDS level is low.
Tip: When one litre of water is purified, 650 ml of water is thrown out by the purifier system. To save water, use the thrown out water for cleaning fruits/vegetables/utensils/house, washing clothes.