Question: "What's the best way to REALLY know what's in my drinking water?"
Answer: "To get a full water quality picture, you may want to consider having your water tested by a local water testing lab but be CAREFUL who you select and avoid those who also, and foremost, sell water treatment systems. Independent labs give independent results whereas a filter company wants to sell you a filter and uses the testing as bait to get you interested in their products. If you cannot locate a reputable independent local lab, companies like National Testing Laboratories offer reasonably priced mail in water testing services with a range of packages that test for basic water quality parameters all the way up through comprehensive packages that include tests for literally hundreds of potential drinking water contaminants."
Find information regarding National Testing Labs' mail-in water test kit packages here.
What do I do if testing reveals a 'problem' in my water?
While no one WANTS to find out their water supply contains unwanted and potentially harmful contaminants, it does happen from time-to-time and when it does action needs to get taken right away to remedy the situation. Regardless of whether the water's problem involves aesthetics (taste, color, odor, etc.) or something far more sinister sinister like higher levels of lead, mercury or chemical remnants, the longer you wait to correct the problem, the longer you expose your family and yourself to all of those problems.
Once you have identified the problem through testing you can set about the task of determining which type of filtration method will work best for your unique water quality situation.
Not all filters are created equal!
When considering INVESTING in a water filtration system, make certain the company whose product(s) you select has an established reputation and that their products not only will meet your filtration requirements, but also that their products meet NSF/ANSI performance requirements for the contaminants you would like reduced/removed.
If the company whose water filter you consider does not make the independent test results from testing of its water filters publicly and readily available, you may want to consider another company's water filtration products.
As an example, the test results for Propur's more popular water filters can easily be accessed:
Countertop Water Filter
Undercounter Water Filter
Propur ProMax PM-9000H
Chrome Shower Filter
with Massage Wand