Simple kits for testing both water and painted surfaces go for $10 and up at Home Depot.  The less expensive ones have two tests.  You should test at least a couple of fixtures because older fixtures often contain lead.  Getting a positive may mean that you need only replace that fixture.  Testing the paint isnt a bad idea either.  If you get a positive then you need to have the water tested by a lab.  It isnt very expensive to get a kit and mail a sample back to the lab.  Your city or county water department should be able to help you find a reliable lab.<p>I am not an expert in the area, but I did serve on the board of a small mutual water company in the hills above Silicon Valley. We were required to do daily tests for things like coliform bacteria and monthly tests for other possible contaminates.  Every few years we handed out lead testing kits to a few households on the various branches of the system to make sure lead wasnt leaching into the water.  All of our samples had to be tested at county approved labs.  A county inspector also took samples during the year.  The testing for larger water systems were even stricter.