Whole house water filters have become more popular as consumers realize that bottled water is usually just the same as tap water. Water filters provide water that costs much less than bottled water, and it has gone through a purification process. Buying a whole house water filter is an important decision, and you need to do your homework before you go shopping. Check a manufacturer’s reputation, and demand documentation. Make sure that the manufacturer has a good customer service reputation with the Better Business Bureau. The manufacturer should be able to provide independent studies that say the filter does what the manufacturer says it does. Manufacturers are required by law to substantiate their claims in some states. If the manufacturer avoids states that require certifications, like CA, IA, or WI, avoid them. You want a manufacturer that has passed stringent testing like these states require. Last, just because a whole house water filter system costs more does not mean that it work better, so don’t just buy the most expensive brand. Read the certified test data instead.