You should start by looking at the capacity. One thing that you should know is that most of the water purifiers come with a storage tank for the purified water. It will therefore depend with the number of people that are likely to drink that purified water. For example, if you have a small family you can choose a tank of 4-7 litres in capacity and 10 litres for big families. It is better if you go for automated water purifiers which will detect when the level of water goes down in the tank and refill it. With this you will be free from purchasing the wrong purifier.
Not only that but you should also check if it is electric or non-electric. This is important as those people who live in places with constant power interruption should purchase water purifiers that can operate without electricity. Like most of the gravity based water purifiers are not electric. Apart from that, maintenance cost of non-electric water purifiers is not that high. Another thing is that electric purifies tend to be more efficient in purifying water than the non-electric purifiers.
Apart from that, you should also consider maintenance and after sales service. Maintenance is very essential in all the equipment not only water purifiers. Without maintenance the water purifier will not work as required. Normally, the supplies of the water purifiers always provide you with free or affordable after sales service. In real sense you will spend less money maintaining non-electric purifier than electric purifier.
Another thing that you should consider is installation and a warranty. You should take advantage of companies that will install your water purifier free of charge. But we also have some companies that will charge you a lot of money on installation. Another thing is a warranty which will allow you to use water purifier for a given period of time and return if it is not functioning well.
Apart from that, you should also check warranty and the ratings. One thing that you should know is that when you want the best water purifier you should choose the one that is highly rated. In addition, you should also consider online reviews as they will give you chance to go through some of the customers comments about different types of water purifiers. The best water purifier should be the one with many positive comments as this shows that the people are satisfied with that particular product.