I am using a panasonic water purifier for the past THREE years without any trouble. The filter has to be replaced every 6 months. I find that tap water in Doha is good and a normal filter suffices. I remember reading a notice from kahraama informing public to avoid filters using reverse osmosis technolgy since the vitamins that are added get lost. By the way me and my family use only the filtered water for drinking .No bottled water.