Lead service lines are generally a dull gray color and are very soft. You can identify them easily by carefully scratching with a key. If the pipe is made of lead, the area you’ve scratched will turn a bright silver color. Do not use a knife or other sharp instrument and take care not to puncture a hole in the pipe.
Note: Galvanized piping can also be dull gray in color. A strong magnet will typically cling to galvanized pipes, but will not cling to lead pipes. Lead service lines can be connected to the residential plumbing using solder and have a characteristic solder “bulb” at the end, a compression fitting, or other connector made of galvanized iron or brass / bronze.