Water: the second time around
SMR Farms in Bradenton, Fla., has a hefty irrigation bill, with more than 4,500 acres under irrigation, but the bill is kept in check by using wastewater from a local treatment plant. The operation was a pioneer in Manatee County in the use of reclaimed water for irrigation, originally bringing the water in to supply citrus trees.
“It’s been very successful here; it’s resulted in very substantial groundwater savings over the life of the system,” says Mac Carraway, SMR Farms president.
The wastewater is usually considered an effluent, but it is environmentally safe by the time it reaches the farm, he says. The safety is ensured by the treatment plants, all regulated by the Florida Department of Environmental Protection under the Florida Administrative Code. The code outlines how and where the water may be used, detailing monitoring and inspections of the treatment plants for code compliance and farm inspections to monitor the safe use of the water according to the plant’s departmental permit.
The Florida Department of Health further requires that edible crops irrigated with reclaimed water that are not peeled, cooked or thermally processed must be watered with subsurface drip and microirrigation systems, and the water must not come in contact with edible portions of the plants. It’s a rule that is found only in Florida, and many believe the rule is overkill for water that is already considered safe.
“Back in the 1980s, the department wanted an added protection that reclaimed water wasn’t going to cause any problems, but other states don’t have that edible-crop requirement and haven’t had a problem,” says Anthony Andrade, senior water conservation analyst, Southwest Florida Water Management District, Brooksville.
• Reclaimed water helps save groundwater resources in the citrus area of Florida.
• Growers see little difference between reclaimed water and aquifer water.
• Finding a source and pricing plumbing are first steps to using reclaimed water for ag.
Rules ensure safe water
The regulations ensure a water source that is clean and environmentally safe, and much of the water is little different from that in the groundwater source regulators seek to protect. There may be traces of chemicals, but it usually isn’t an issue.
“It has some nitrogen in it when you get it, some chlorine in it, but none have had any adverse impacts on our growing practices. You would never know anything was different,” Carraway says.
Reclaimed water isn’t available in all areas, even in Florida, which leads the world in reclaimed water irrigation. Many treatment plants don’t provide the water for irrigation, so the first step in adopting it as a water source is to find out if it is available for irrigation.
Customers typically contract with the local water utility to connect to the utility’s reclaimed water pipe system in their area, and depending on the location of the reclaimed water transmission pipes, it may actually be more economical to stay with groundwater or surface water.
The pressurized pipes easily connect to the farm’s current irrigation systems, and once connected, the water flows without the need for extra pumps or energy, potentially making the reclaimed water cheaper than groundwater. The only added expense is a filtering system to strain out solid particles that may have precipitated during transmission.
“Initially, we discovered it required filtration, especially for our low-volume system. Once those [problems] were addressed, it was a matter of designing the system to use reclaimed water or groundwater,” Carraway says.
Reclaimed water saves money
The price of reclaimed water is reasonable, averaging from 5 to 50 cents per thousand gallons in Florida. It is usually exempt from watering restrictions placed on groundwater resources, which are hindrances to irrigation in many parts of Florida.
Plus, there are local incentives to make reclaimed water more appealing, as well as lowering the initial cost of connection to utility lines and system installation.
The Southwest Florida Water Management District offers up to 50% funding for reclaimed water projects, and requires reclaimed water use where available, while allowing the farm to continue to use groundwater to back up or supplement the irrigation should reclaimed water be lost due to low pressure, line breaks or power losses.
Two sources of water offer a second benefit to producers because like groundwater, reclaimed water is a limited resource and isn’t available in all areas. It also must be shared by many different customers.
“In some areas, it has already been fully allocated, and some utilities run out of reclaimed water in the dry season,” Andrade says.
The biggest benefit to reclaimed water use is environmental. It protects the groundwater resource from further depletion, by reusing water and leaving more potable water in the aquifers, Carraway notes.
Brazil writes from Clermont, Fla.
This article published in the February, 2010 edition of IRRIGATION EXTRA.