Environmental pollutants, harmful bacteria, and parasites can contaminate rainwater, and drinking it can make you sick. Boiling, Filtering and Chemically Treating Rainwater Can Help Make It Safer for Human Consumption. A properly maintained rainwater tank can provide good quality drinking water. As long as rainwater is clear, has little taste or smell, and comes from a well-maintained water intake system, it is likely to be safe and unlikely to cause illness for most users.
While useful for many things, rainwater isn't as pure as you might think, so you can't assume it's safe to drink. Rain can carry different types of pollutants into the water you collect (for example, bird droppings on the roof could end up in the barrel or water tank). Rainwater can carry bacteria, parasites, viruses and chemicals that could make you sick, and has been linked to disease outbreaks. Drinking rainwater can also improve human digestion due to its alkaline pH content.
Rainwater has the same pH as distilled water, so it helps neutralize blood pH levels and promotes stomach functions. Many experts say that untreated rainwater may not be safe for human consumption, even though national guidelines suggest that the risk of getting sick from drinking rainwater is low. Rainwater is generally a safe and reliable source of drinking water. A well-maintained and well-managed supply system helps to further protect water quality.
The microbiological quality of rainwater collected in domestic tanks will be worse than that of many public water supplies. Communities where residents receive treated public water for drinking, homeowners and businesses are increasingly turning to rainwater collection systems to address non-potable water needs, such as garden irrigation, especially in dry regions. This “first flush” can be used for washing, watering plants, or other non-drinking uses. When rainwater is used as a source of supplemental water, homeowners should ensure that rainwater cannot enter pipes that contain drinking water.
If the roof catchment and tank are well maintained and the water looks, smells and tastes clean, the risk of getting sick is low. Drinking rainwater is not expensive and is the main source of water in areas where people cannot access clean tap water or any other water supply. If mosquitoes can access tank water, it can become a breeding ground for insects that spread diseases, said Dr. Moglia, who was part of a research project that inspected 450 tanks in Melbourne.
After cleaning, it is recommended to rinse the internal walls and floor of the tank with clean water. Collecting, storing and using rainwater, called rainwater harvesting, can be an effective way of conserving and reusing local water. The research of Dr. Ross has examined the levels of zinc, lead, chromium, copper and cadmium in water tanks in South Australia.
If your home is over-sprayed with overhead chemicals, clean the collection pipe of your rainwater tank to prevent pesticides from entering the tank. Alternatively, the tank inlet should be disconnected so that the first rain runoff after a dry season is not collected. And check that your mesh is in good condition every three months; a recent CSIRO study found that more than 10 percent of the water tanks inspected had mesh that was in poor repair condition enough to allow pests and vermin to enter the tank. So filter water to remove metals, but if your roof has received a lot of ash from nearby fires, it might be worth taking a water test to make sure poisonous metals don't get through.