1. Locate the water line
Locate the water service line entering the building. You need to see the pipe where It comes through the floor or wall. It is likely located in the basement or lowest floor, or whole-house water shut-off valve near your water meter. Testing should be done where the service enters the building, before the shut-off valve and the water meter. In some instances, a very short length of lead pipe may enter the house before transitioning to another material.