You can use harvested rainwater for many things: watering the plants, washing your clothes, and even flushing the toilet. But water, or at least the water that comes in bottles or from our taps, is something we usually associate with drinking. Which raises one question: If you can do all of this with harvested rainwater, can you drink it?
The answer is yes, but only if you treat it and collect it in the correct way. So don’t stick your head under your water butt’s tap and take a gulp. Instead, read on to find out how drinking harvested rainwater can be dangerous, and what you can do to make it safer to consume.
Why drinking harvested rainwater can be dangerous
Rainwater is likely to be pure when it starts falling from the sky, but on its journey to your water butt, there’s a strong chance it will become contaminated in a number of different ways. First, it can pick up harmful particles from the air, like dust, smoke or pollutants. Then it can pick up dirt, bird droppings and other contaminants as it washes over your roof and through your gutters. Far more than “just a bit of dirt,” these contaminants have been linked to serious health risks and should be avoided at all costs. In some cases, they can be deadly.
Despite these risks, there are many people around the world who do drink harvested rainwater, particularly in countries where water supplies are scarce. The World Health Organisation (WHO) has warned of the risks of drinking rainwater. In its published guidelines they state that “well designed rainwater harvesting systems with clean catchments and storage tanks supported by good hygiene at point of use can offer drinking-water with very low health risk.”
If you have one of these rainwater harvesting systems, your water should be safe to drink. So what counts as a system with “good hygiene” and how do you get one?
How to make rainwater drinkable
The first step towards creating a safe-to-drink rainwater harvesting setup is minimising the contaminants that could make it into your water butt in the first place. Start by moving (or removing) any plants and trees that hang over your gutter. Most systems will come with filters and diverters of their own, but make sure you have the best diverter you can find to catch debris, and an effective downpipe connector that filters the water. This will make your tank far cleaner, and your water much safer.
There’s still work to do, though. Even the best filters will struggle to remove microscopic parasites and viruses from any rainwater that has been collected. To stay safe from these, you need to disinfect the contents of your water butt. There are several methods you can use to disinfect rainwater. Some of them should only be carried out by experts, though, as it can be difficult to ensure their effectiveness.
Perhaps the most straightforward disinfection technique is using a UV sterilisation system. These systems shine ultraviolet light into water to penetrate the cells of any organisms in contaminating it, rendering them unable to reproduce, and therefore making them harmless.
For more information on safely drinking rainwater, visit the WHO’s rainwater harvesting page. Browse our collection today to find all the equipment you need to harvest and drink rainwater at home.
