Rain barrels and water safety

By Diane Wright Hirsch, MPH, RD - UConn Extension Educator/Food Safety
Featured Article - posted Tue., Apr. 16, 2013
Be safe when using water from rain barrels. Courtesy photo. - Contributed Photo

It really has been an unpredictable winter and spring with raging late-season snowstorms and unseasonably cool early April temperatures. What this growing season will bring in terms of precipitation is anyone’s guess.

To mediate the unpredictability’s of New England weather, many are opting to install a rain barrel. Rain barrels collect and store rainwater, usually from rooftops and downspouts. There are several reasons folks have started to use rain barrels. They are one way Connecticut residents can conserve water (to save on the water bill or reduce stress on a well water system) and to reduce storm water runoff, which can cause flooding and erosion and carry pollutants into water systems.

If storms bring on power outages, rain barrel water can fill some of the need for emergency water supplies. It can certainly be used to flush toilets for those that have a well water systems and no generator to run the pump. But, you must treat or boil rainwater for washing, drinking or cooking during an emergency, when potable water is not available. Water can be the source of a variety of pathogens or microorganisms that cause food or water borne illness, including E. coli O157:H7, Salmonella spp., Cryptosporidium parvum, Giardia lamblia, Cyclospora cayetanensis, and some viruses.

Gardeners generally obtain irrigation water from three sources: municipal or public water systems that are monitored and treated for contaminants; private wells that should be tested annually to determine if the water is safe and unlikely to contaminate produce; and surface water (ponds and streams), which is most likely to be affected by watershed activities and season and, therefore, present the greatest risk of contamination from harmful pathogens.

Rain barrels have become quite popular, but there is not a lot of research out there addressing the risk of microbiological and/or chemical contamination from this water source. Because these barrels catch the rain off your roof (that same roof where pigeons, squirrels and other wildlife like to frolic and perch), some contamination is inevitable. Bird and other droppings will be washed off the roof into the barrel. Bacteria and moss grow on cedar and asphalt roofs. Roof materials, chemicals, copper, or asphalt can affect water quality. After a dry spell, divert the first collection or “first flush” of rain, which is more likely to contain some of these contaminants.

So, like surface water, rain barrel water is a water source that is most likely to be contaminated with both microbiological and chemical contaminants. Some sources will tell you that the amounts are likely not to be significant in most cases, especially if the water is going directly into the ground and not directly on the plant. However, some research has also suggested that there may be, in some plants, uptake of microbes and other contaminants from the soil.

So what is a gardener to do? The best advice is to use this water source the same way that other nonpotable water is used. Avoid sprinkling or watering from above with a hose. It is best to use this water for drip or trickle irrigation, directing the water at the base of plants - this prevents contamination of edible, above-ground plant parts that are hard to clean, especially leafy greens. Do not use rain barrel water close to harvest time, when more of the edible portion of the plant is exposed to the water. It is possible, though maybe not terribly practical, to test your rain barrel water. At first, it might be useful to determine what chemical contaminants are coming off your roof. However, microbiological testing may not be very useful, as you are more than likely going to find something. So just assume some pathogenic microbes are there, especially if the water is allowed to sit for a while in warm summer temperatures.

Finally, never use this water to wash fruits or vegetables from the garden or orchard prior to eating. (But, remember to always wash thoroughly with potable water before eating.)

Additional tips on the safe use of rain barrels:

Only use barrels made from food-grade plastic or other materials.

Check your rain barrel on a regular basis to make sure all openings are clean, free of debris, bugs, nests or other sources of contamination, and flowing freely.

Cover the intake hole with a plastic grate or skimmer basket covered with a nylon stocking or fine mesh screen to prevent debris, rodents, or bugs from getting inside your rain barrel.

Do not let the standing water in your rain barrel become a breeding place for mosquitoes. If necessary, add a tablespoon of vegetable oil to your barrel to prevent breeding or use “Mosquito Dunks.”

Plant debris that accumulates in the bottom of your rain barrel can support microbial growth. Be sure to clean out debris that settles to the bottom of your rain barrel at least once a year (or more often, if needed, and always before using at the beginning of the season). Wash with detergent, scrub and finish with a sanitizing rinse of one tablespoon of bleach to a gallon of water. Allow to air dry.

Be aware of other safety concerns. If you have small children or pets, be sure that your system is constructed so that kids and animals cannot get into the barrel and so that the barrel may not be pulled down. A full barrel can weigh as much as 450 pounds!

For more information about the use of rain barrels, contact the University of Connecticut Home and Garden Education center at www.ladybug.uconn.edu or 1-877-486-6271.

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