As mentioned, your municipality has a legal obligation to provide you with safe water (those on wells are not under this category) and publish their findings of what is in the city or towns water. This gives us and you a good idea of what is in your homes water.
Outside of that, testing should be done by a certified lab for the most accurate readings. The cost of such tests can run anywhere from $100-$300+ depending on the quantity of items being tested for. Pure Source Water Systems is happy to assist in getting your water tested if desired.
DIY or at home tests are not as reliable and often provide false data, especially with regards to water hardness and pH. While they do an OK job for some parameters, many readings are off and sometimes significantly when compared to a lab test. Companies that test your homes water on site with a kit are not providing you with reliable data and are using this test for showmanship and sales more than anything else.
We have seen hardness readings off by by 40% with home test kits but when a company is selling you a $3000+ softener, that is in their best interest. (Keep in mind a softener does nothing to filter contaminants from you water)
Bottom line is to use a certified lab for the most reliable and accurate results.