I have a garlic bulb in my water tank, and the watering can i use to fill the drinkers. For all the good it does, i'm syre it doesn't do any harm, my doos are in great order. I add 250ml of cider vinegar to the water tank every so often, which means they will get it for 5 days, before the tank is empty. I then refill the tank leaving the garlic in until it grows stems, then i put a fresh one in, again its no done them any harm