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Check out UN-Habitats guide for rapid assessment of the bacterial quality of water. It covers sampling, how to conduct the test, contact information of the suppliers, interpreting, recording and presenting the results with COLILERT (also a presence/absence test) and Petrifilm (previously mentioned by RotaryStewart).
These test are cheap and does not require lab knowledge.
https://www.unhabitat.org/pmss/getElectronicVersion.asp?nr=3056&alt=1