Wednesday, June 24, 2015

Rain Barrels and Pipe Dreams: Separating the Feel-good from the Effective with this Popular Water Conservation Practice

By Mackenzie Boyer and Michael Gutierrez

With thunderstorms aplenty this season, it’s tempting for homeowners to install rain barrels to capture a bit of extra runoff from their roofs. Rain barrels give residents a visible way to support water conservation, and people who use them tend to adopt other conservation measures. But when it comes to the big picture of water sustainability in Florida, rain barrels may not be the best conservation tools. Misconceptions about their benefits abound. Here’s a look at the top five myths surrounding rain barrels:

Baseball, apple pie and a rain barrel
MYTH 1: RAIN BARRELS SAVE A LOT OF WATER: Even with all the rain we have in Florida, rain barrels are too small to save much. With about 60 inches of rain a year, Florida seems like a natural fit for rain barrels, but Florida’s rain is blessed with bad timing. Yards usually need the most water in the spring, but there isn’t enough spring rainfall and storing winter rainfall until the spring isn’t practical. 

On the other hand, summer thunderstorms can drop several inches of rain at once, much more than a rain barrel can store. Using a 50-gallon rain barrel as the standard, it would take about forty rain barrels to irrigate a typical Florida yard once. In west coast numbers, UC Davis professor Jay Lund posits that a rain barrel can replace about 0.1 percent of a Californian’s home water use. Although Floridians can store and use rainwater more often than drought-stricken Californians, the impact on our total water use would still be small.

MYTH 2: RAIN BARRELS SAVE MONEY: Just because rainwater is free doesn’t mean using a rain barrel is cheaper. Tap water costs customers about $3 per 1,000 gallons (the cost varies by utility). A 50-gallon rain barrel that costs about $100 would need to be filled and emptied about 667 times to be cheaper to a consumer than using tap water (or 334 times if purchasing from an Extension program at roughly $50).

MYTH 3: RAIN BARRELS HELP PREVENT FLOODING: Rain barrels have no impact on flooding. A 2011 study of rain barrels in Chicago found no link between rain barrels and localized flooding. To collect the first ½ inch of rainfall (a typical minimum amount recommended for stormwater control) off a 1,000 square foot roof, about six rain barrels would be needed.

MYTH 4: RAINWATER IS CLEANER: Water from a rain barrel may not be cleaner than tap water. Rainwater itself might be cleaner than tap water, but rooftop runoff may not be. Most rain barrels don’t have bypasses to avoid the first flush of debris and pollutants that may wash off a roof, so those contaminates could end up in the rain barrel. Further, rooftop runoff usually flows through an insecticide-treated screen (used to prevent mosquitoes from breeding and any trash from entering) and into the barrel. 

MYTH 5: BY REDUCING WATER USE, RAIN BARRELS REDUCE ENERGY USE: Rain barrels may have a larger carbon footprint. The rainwater doesn’t require treatment and pumping like tap water, but the plastic barrel requires energy to be produced. The carbon footprint of a 50 gallon plastic rain barrel (not including piping, inlet screen, or spigot) is equal to driving a mid-sized car about 25 miles, but using 50 gallons of tap water is equal to driving a distance of about 0.14 miles. A rain barrel would need to be filled and emptied about 180 times before its carbon footprint is equal to the carbon footprint of using tap water. Since Floridians probably fill and empty their rain barrels about ten times per year, it would take about 18 years for a rain barrel to have the same carbon footprint as tap water.

Large cistern action in Carrboro, NC.
Don't Stop Believing
So should we just give up on rain barrels? Not necessarily. But we also shouldn’t continue to over-estimate their benefits. Thinking bigger than rain barrels is a better option. Glenn Acomb, a landscape architect at the University of Florida, recommends thinking about cisterns and green roofs. The key, he says, is to make the rainwater storage large enough to make an impact.

UF/IFAS Irrigation Specialist Michael Dukes recommends playing offense and defense with water conservation: looking to alternative water supplies like rainwater harvesting while also finding ways reduce irrigation demand, such as following Florida-Friendly Landscaping (FFL) principles.  

Do you know your nine principles?
Characterized by their use of native and drought-tolerant plants and efficient irrigation, FFLs provide a multitude of benefits. In addition to water conservation (using about half as much irrigation as traditional landscapes, or none at all), FFLs can create habitat for birds, butterflies, and bugs, reduce fertilizer use, and protect downstream water bodies. And that’s more than anyone can expect from a 50 gallon rain barrel.  
Special things begin with gutters: rain gardens are also a stormwater management option