1. Can it filter salty water?
Yes but it depends on the technology used in the filter. Reverse osmosis (RO) is a popular filter for purifying saline water.
2. Can it run without electricity?
Not all filters are required electricity such as simple water filter. But RO water purifier requires electrcity and will stop filtering once the power cut off. However, most RO system has a reserved tank to store water and will continue supply the water using the tank pressure until the tank is empty. That's why this reserved tank sometimes called as pressure tank.
3. What is the pH after filtration?
The standard pH of water is 6-8. After filtration, the water pH will be 6-7 which is very safe. For some filtrartion technologies, you can make the water more alkaline using addtional cartridge.
4. What will be the TDS after filtration?
500 mg/L is a safe TDS for any filtration technolgy. You need to chcek your water TDS using a TDS meter.