You can sterilize Dirty Water by mixing with alcohol. People with questionable water only drank water mixed with alcohol for over a thousand years in the old world. From the Ancients through the Dark Ages into the Middle Ages until the enlightenment when coffee and tea caught on which sterilized the water. In the north it was often just beer not mixed with more water than that, in the south they cut wine with water, IDK the exact ratio, maybe one third Wine to Water. From the Greeks and the Romans onward when waterborne diseases were present as they were able.