Great question! For the US, you will need a degree in Molecular Biology/Microbiology or a Medical (Laboratory) Technologist. You'll then either need to live near the city where one of the few private companies that do wastewater testing ar e(my case), or live near a public health lab that does ww. Pretty much all state public health labs do it, but city/county level varies immensely. For the government route, look at APHL or NACCHO to find information on your local public health labs. There are a few universities that also do ww testing, for example I know University of Illinois, University of Missouri and Michigan State are all doing a bunch of wastewater work.