@greenrun, thank you for always sparing time to read my post. tolerance to bad water, if that is the case then the recent Cholera outbreak in Adamawa state won not have occurred, the increase in the incidence of typhoid and gastroenteritis in our hospitals especially for those of us in "rugged areas" would have been a thing of the past. The reasonable answer to this development of tolerance is because our immune system is functioning at its optimal state, any suppression in the immune response will result in infection if contaminated water is consumed.

The effect of drinking bad water also depends on the microbial of the water and the pathogenic ability of the organisms involved, therefore @greenrun, we are been saved by the immune system's ability to wade into a successful fight with pathogens.