New Vegetable Gardener — Irrigation with Reclaimed Water
I often get questions relating to the safety of using reclaimed water in gardens. I don’t know if you will find yourself in that situation but here are the answers you will need if the question comes up: One of the largest obstacles to reclaimed water use on edible crops is public perception, mostly resulting from a lack of adequate education. Public health concerns include the presence of pathogens and heavy metals, which are typically of little concern following proper treatment of domestic wastewater. In terms of crop productivity, there are concerns regarding the high salt (nutrients/fertilizer) content of reclaimed water.
Overwatering with reclaimed water may result in salt accumulation in the soil, resulting in poor root growth and water uptake by crops. It is important to note that tolerance of reclaimed water use varies by crop type. Although the organic and inorganic nutrient content of reclaimed water can benefit users by reducing the need for some fertilizers, high nitrogen concentrations may result in excessive microbial growth and activity and be detrimental to crops. If overwatering leads to heavy runoff, these nutrients may also pose a water quality risk to surface water bodies.
Orange County states: “The primary use (of reclaimed water) will be landscape irrigation, but you may also use reclaimed water to irrigate fruit and vegetable gardens. In-ground sprinkler systems must be used for reclaimed water irrigation. Orange County does not allow the use of hoses or spigots for irrigation with reclaimed water. Fruits and vegetables that are usually peeled (such as citrus), skinned or cooked (such as potatoes, beans and squash) can be irrigated. Reclaimed water cannot be sprayed directly on fruits and vegetables that are eaten raw and are not peeled or skinned prior to eating (such as lettuce or tomatoes). Drip irrigation systems must be used for irrigating these types of crops with reclaimed water.” (source: http://www.orangecountyfl.net/Portals/0/Library/Water-Garbage-Recycle/docs/Reclaimed_Water_Customer_Guide.pdf ,page 3)
The City of Orlando allows the use of reclaimed water on vegetable gardens: “Vegetable gardens may be irrigated using indirect irrigation methods such as drip systems so that reclaimed water does not contact produce that will be eaten raw. Fruit and vegetables that must be skinned, peeled or cooked before eating may be irrigated using direct contact methods of irrigation such as sprinklers.” (source: http://www.cityoforlando.net/waterreclamation/reclaimed-water-for-urban-irrigation/)
The State of Florida allows the use of reclaimed water on vegetable gardens. “The Florida Department of Environmental Protection states that reclaimed water should NOT be directly applied to the surfaces of vegetables or other edible crops that are not peeled, cooked, or thermally processed before being consumed. This statement essentially means that as long as you peel or cook your vegetables, they may be safely consumed after being grown with reclaimed irrigation water. The statement also means that indirect application methods, such as ridge or furrow irrigation, drip irrigation or a subsurface distribution system, which preclude direct contact, are allowed for edible crops that are not peeled, skinned, cooked, or thermally processed before consumption.” (source: http://edis.ifas.ufl.edu/pdffiles/SS/SS54400.pdf , see question #10)