Testing for MSRA/Staph in your home
When we finish a project we make the plumber test the water by sampling at least two faucets. 

They take the samples to our local medical testing lab. Be sure to tell the lab what they’re testing for...because they’re usually testing for fecal matter. 

Maybe you could call a local plumber and see who they use and what they use for taking the samples. (The testing lab will want to establish a chain of custody on who took the samples, where the samples were stored, etc.)