Ok so I searched but can't seem to find any information on this. My DH made an automatic waterer for the girls using a rain barrel that collects the rain water then feeds into a halved pvc pipe. All seems to be working fine then we thought about the possibility of bacteria from sitting water / it doesn't sit forever but it does take them some time to drink down the barrel . Does anyone know if there is any issues with possible bacteria or anything I could put in the water to make it safe for the girls that is natural . Poss apple cider vinegar ??? Up for any suggestions .