Remember, never give your credit-card number over the telephone to someone you do not know. The Federal Trade Commission suggests that you take the following steps before you have your water tested or you purchase any type of water treatment system. Offers to test the tap water in your home for free are almost always part of a sales promotion. Avoid dealing with salespersons who tell you strictly on the basis of their in-home testing that your drinking water is polluted, contaminated, or bad for your family's health. Be Wary of Claims of Government Approval.
Fraudulent sellers use many different sales techniques.
Some fraudulent sellers claim that certain government agencies require or recommend widespread use of purification systems. Others claim that the government has approved a particular method for in-home water testing. Still others claim that the government has approved or licensed a particular water treatment unit or purification system. All of those claims are false. The government does not endorse water tests or water treatment products.