Rainwater. It sounds clean and pure, right? Catching rainwater in a barrel can be a great way to conserve resources. But according to the Centers for Disease Control, “Rain can wash different types of contaminants into the water you collect (for example, bird poop on your roof could end up in your water barrel or tank). Rainwater can carry bacteria, parasites, viruses, and chemicals that could make you sick, and it has been linked to disease outbreaks.”
One common parasite in a rain barrel is Giardia, a type of protozoa. It is transmitted from feces to mouth through food or water, and alters the intestinal environment, interfering with the absorption of vitamins and nutrients, and with the digestion of fat. Infected birds often have diarrhea and show symptoms of malnutrition.
Watching our own chickens after it rains, they seem to prefer drinking from the “poop puddles”, no matter how much clean water they have. It doesn’t seem to bother them. But recently we heard a story of someone who started giving water to their quail from a rain barrel. Within about a week, most of them became lethargic and died. The cause of death was unconfirmed, but the only systemic change to the flock was water from a rain barrel.
There are treatments available for protozoal infections, including carnidazole, metronidazole, fenbendazole, and toltrazuril. Common brand names for fenbendazole are Panacur® and Safe-Guard®.
So if you catch rainwater, use it to water your plants. But keep it away from animals and humans.