The first thing to consider before buying a water filter pitcher is the chemicals and contaminants in your water. Ideally, a professional can check the level and type of metals and bacteria in your water to ensure that you get the best water filter pitcher to suit your individual water supply.
Second, consider the material construction of the water filter pitcher. While most are made from plastic, which contributes to their lightweight and portable nature, a thick plastic build will also make them durable.
The filter life is an important consideration. The best water filter pitchers will use filters with a long life and will only require the filter to be replaced after a couple of months.
Next, consider the capacity of the jug. If the filter pitcher is for personal use, then a smaller capacity will work fine. However, if you are buying for the family, a bigger capacity will save you from having to continuously refill the jug.
The design of the water pitcher should be simple enough to enable you to easily clean the jug. A water filter pitcher that has sharp corners and edges could offer places for bacteria to hide and breed.