It seems a little absurd to talk about collecting rainwater for seasonal watering needs in the landscape since we have had more than enough rain this spring.
However, I thought it still important to remind homeowners about the use of water from rain barrels.
While the water is naturally soft and devoid of added chemicals such as chlorine, there is an ongoing question, “Do contaminants run off the roof with the water?” In 2011 researchers at Rutgers University tested rainwater collected from asphalt-shingled roofs to determine its safety as a water source. They tested for lead, zinc, total coliforms and E. coli, and compared the test results against the federal irrigation water standards and New Jersey drinking water standards.
Their findings reported that none of the study locations violated the irrigation or drinking water standards for zinc. There were no samples that exceeded the irrigation water standards for lead, but 4 percent of the samples exceeded the New Jersey drinking water standard for lead.
The test results for total coliforms showed that 100 percent of the samples exceeded the drinking water standard. While total coliforms are used as an indicator of potential contamination, they are a poor indicator of human pathogens, therefore they included E.coli testing. These test results found that 9 percent of the samples exceeded the irrigation standard and 66 percent of the samples exceeded the drinking water standard for E.coli. The suspected source of the E. coli bacteria were wildlife, squirrels and birds, which were observed on the rooftops at the sampling locations.
So what does this mean for rainwater collected in rain barrels and its use in our landscape? In this study, researchers at Rutgers offered some best management practices when using water from rain barrels. They recommended the addition of one ounce of 5-6 percent bleach per 55-gallon barrel per month, except during frequent rainy periods, they recommended the addition of bleach twice a month. Additionally they recommended a 24 hours waiting period after bleach addition to allow the chlorine to dissipate before using to irrigate plants.
Finally, they recommended that if the water is used in a vegetable garden, gardeners should allow the leaves to dry before harvesting, or only apply the water to the soil, such as with a drip irrigation system. Further, thoroughly wash all harvested vegetables before consumption. Washington State University Extension also provides recommended practices for using rain barrel water in their publication titled, “POTENTIAL CONTAMINANTS IN RESIDENTIAL RAIN BARREL WATER”. The publication number is FS280E, and found at https://extension.wsu.edu/ .
Capturing and reusing rainwater can help reduce the cost of utility water bills, especially when homeowners have installed multiple rain barrels. During the summer months, it is estimated that nearly 40 percent of household water is used for lawn and landscape maintenance. Therefore rain barrels can assist in reducing this summer demand. If you have any questions, feel free to contact the University of Illinois Extension office in Charleston at 217-345-7034.
For more information on University of Illinois Extension programming in Coles, Cumberland, Douglas, Moultrie and Shelby counties, visit our website at http://web.extension.illinois.edu/ccdms/index.html or call us at 217-345-7034.