Water is an essential resource for each of us, and, if you’re responsible for crops and livestock, you can’t afford any disruptions in its supply. As a result, some farms install their own water storage systems as a hedge against increasing periods of drought and extreme weather. These can be as simple as a few extra rain barrels or as complex as a 3,000-gallon, food-grade cistern.
In part, knowing which cistern type, size and location might be right for you depends on your intended uses for the water you collect. For instance, without access to publicly available, treated water or a nearby spring or well, private rainwater collection and storage can be a household’s primary source of drinking water.
In these cases, large cisterns are typically situated so that rainwater collected from the roof can be treated and pumped directly to the house.
Household Systems
Household cistern systems for drinking water are fairly complex to set up and maintain. “Periodically draining, disinfecting, cleaning and refilling the tank is something that people who have cisterns as their drinking water supplies for their homes … have to [do] periodically,” Jennifer Fetter says. Fetter works as an extension educator in Water Resources for Penn State Extension.
“You want to make sure it’s free of human pathogens and other health risks before you drink it,” she continues. (That goes for using it with livestock and pets, too.)
Non-treated, non-potable water does have some uses indoors. “Rainwater catchment systems connected to toilet flushing is something that a lot of environmentally friendly buildings have adopted,” Fetter explains.
Read more: Here are some tips for getting started with rainwater collection.
Gardens & Landscapes
Even if you aren’t planning to drink the rainwater you collect, you do need to think carefully about the way you use it. Harvested rainwater is great for watering non-edibles. But vegetables you plan to pick and eat raw—like spinach, lettuce and other salad greens—are particularly susceptible to contamination from E. coli bacteria and internal parasites such as Cryptosporidium and Giardia.
“When rainwater runs over your rooftop, think about who else is hanging out on your rooftop,” Fetter explains. “You’ve got birds, raccoons and squirrels up there, and they’re not minding where they go to the bathroom. All of that is getting washed into … those cistern systems.”
Different kinds of roofing shingles and even the walls of your rainwater catchment containers can leach volatile chemicals into your water, too.
Testing & Treatment
“You want to think about testing, if you’re going to end up having to use the water for something more than washing, [flushing] toilets, and landscape and gardening,” Fetter says.
“Test your water, find out what kind of contaminants you’re dealing with, and find out what kinds of treatment systems can address those contaminants, so that you’ve got that treatment system at the ready in the event that you need to use it.”
She recommends using a state-accredited laboratory. Not sure where to start? “It’s a little different in every state. But, generally speaking, either the state’s Department of Health or their Department of Environmental Protection has something to do with drinking water safety and testing,” Fetter says.
The Environmental Protection Agency also offers online resources including state-by-state lab listings. Once you get test results back, you’ll know what problems you need to correct. Chemical chlorination and UV light application are the two main methods used to disinfect water.
And, from carbon filtration to reverse osmosis and beyond, there are many different water filtration systems available to help eliminate various pathogens and impurities.
“There is no perfect filtration system that can solve all problems,” Fetter cautions. “You should find out what kinds of things are in your water so that you know what kind of treatment you might need.”
Read more: Check out this video on collecting rainwater to fill you farm pond.
Placement
If you do opt to add a cistern, your intended uses and climate can help dictate whether it goes above- or below-ground. “One of the benefits for an underground cistern is that you don’t have to worry about it freezing if you live in a part of the United States that gets pretty cold winters,” Fetter says.
So, if you’ll need year-round access to your stored water and you live in a cold climate, you’ll likely need an underground tank. However, these can cost several thousand dollars to install.
If you’ll only access harvested rainwater during the growing season and you live in a relatively warm climate, you can likely get away with leaving smaller, above-ground containers outside year-round. But those in colder climates should drain and store water storage containers until after the last frost.
Finally, Fetter cautions, “There are still some places in the United States where … you can’t harvest rainwater without a permit. So, you need to know your local laws and make sure that you’re not setting up a cistern in a place where the water rights are owned by someone else.”
