The under sink water filters are the only way you can get clean and drinkable water from the main water supply. If you like to save money on bottled water, help saving the environment by reducing the number of water bottles ending up everywhere, consider to have an under sink water filter.
When selecting an under sink water filter the first thing to consider is what you want to take out of the water.
The range of filtration needs can be from a simple unappealing taste to harmful chemicals. You may start by getting a water test to see what it is that is making the water taste funny. Check with your water company to see if they provide a testing service or if they publish a routine report. Alternatively, there are test kits available at local home improvement store or on the internet.
If the tap water is already of pretty good quality but you want a chlorine and sediment filter to improve the taste then a small 1 or 2 stage water filter may be all that is needed. If the water needs a little more work then you might consider a 3 stage water filter that can take much more out of the water giving you a much improved flavor and quality.
For the best in under sink water filters you may consider a reverse osmosis system. R.O. units can filter more out of the water than basically anything else on the market. A small list of things you can remove with reverse osmosis systems includes Arsenic, Chloride, Copper, Iron, Lead, Mercury 2, Sodium and much more.