Water companies make efforts to reduce the risk of microbial contamination in drinking water. A widely used strategy is to introduce chlorine into the drinking water distribution system (DWDS). A subtle potential risk is that non-lethal chlorine residuals may select for chlorine resistant species in the biofilms that reside in DWDS. https://www.bekindtopets.com/top-super-Rx-Cystorelin-gonadorelin-diacetate-tetrahydrate-Solution-Vial-for-Cattle-mega-choice/