~A look at how reclaimed water is produced, what’s in it and how it can be used on lawns and food crops.~
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Florida is rightly known as the Sunshine State. My hometown of Tampa is blessed with an average of 244 days of sunny or partly sunny skies every year, and I love it! There’s another name we could also proudly claim: the water state. Water unites us as Floridians because no matter where we live in the state we touch, cross, and interact with our abundant natural water resources in some way. A study released in 2016 by the UF PIE Center reports that Floridians rank water second only to healthcare as a “highly or extremely important” issue.
As nearly 1000 people a day move to Florida, development and urbanization impact both the supply and the quality of water available to our citizens. Looking ahead to future water demand scenarios, we are likely to need an additional 300 million gallons a day within the next 20 years. Recognizing this need, local and state government agencies and planners are putting more emphasis than ever on expanding the beneficial reuse of reclaimed water. While Florida already leads the nation in use of reclaimed water, we still put on average only 45% of statewide reclaimed water flows to some kind of beneficial reuse. Projects are popping up all over the state to grow that number, and it will be important that we understand the basics of how reclaimed water is produced, regulated, and put to use.
Below are some frequently asked questions about reclaimed water. You can also check out our online publication series on Reclaimed Water in the Landscape.
What is Reclaimed Water?
Reclaimed water, also known as recycled water or reuse water, is former domestic wastewater that has been disinfected and treated to remove solids and certain impurities. After treatment at a wastewater treatment plant, the cleansed water can be safely discharged into a nearby stream, wetland, or ocean, or this water source may be piped back into communities for reuse by various residential, industrial, and commercial users. Unless the reclaimed water is sent back to communities for some kind of beneficial reuse (such as lawn irrigation), it can be discharged to a local water body as a means of “getting rid of it.” Beneficial reuse by neighborhoods, cities, and counties is a promising way to recycle this water and save potable water resources from being used for activities such as lawn irrigation.
How is Reclaimed Water Produced?
Reclaimed water is produced at a wastewater treatment plant. At the treatment plant, domestic wastewater is collected from households, schools, offices, hospitals, and commercial and industrial facilities, and then undergoes several stages of treatment to prepare the water for reuse or discharge into the environment. The treatment processes are designed to ensure that reclaimed water is safe and reliable for its intended use.
The stages of treatment include the following:
- Primary treatment—the sewage is temporarily held in a basin so solid waste materials can settle to the bottom and be removed.
- Secondary treatment—after the solids are removed by primary treatment, the water left behind is further treated to remove or degrade any remaining wastes still suspended in the water.
- Tertiary treatment—a final stage that involves advanced removal of nutrients and other contaminants not fully removed by secondary treatment
Note that the minimum requirement in Florida for treating reclaimed water is secondary treatment and disinfection, although many treatment plants use tertiary treatment for advanced removal of nutrients.
How Does Reclaimed Water Differ from Drinking Water?
Reclaimed water is highly treated and disinfected but still contains some constituents at levels outside the desirable range for drinking water. Specifically, reclaimed water may have higher levels of salts, nutrients (nitrogen and phosphorus), and pathogens (e.g., bacteria and viruses). Reclaimed water has been safely used for non-drinking purposes in Florida for more than 40 years, but because of its composition, this water source should never be used for drinking or sanitary purposes.
Are There any Contaminants in Reclaimed Water?
Reclaimed water is known to contain small concentrations of inorganic and organic contaminants. There are NO documented cases of adverse health effects from contact with reclaimed water in Florida, but you should be aware that pathogens, nutrients, salts, metals, and emerging contaminants (for example, traces of pharmaceuticals) have been detected in reclaimed water. More information about these can be found here.
Is Reclaimed Water Safe for Turf and Landscape Plants?
Reclaimed water can be safely used to irrigate turf and most other landscape plants. In fact, reclaimed water often contains nutrients (nitrogen and phosphorus) that can be considered part of the fertilizer needs of the landscape. Check with your reclaimed water provider to learn about the levels of nutrients in your reclaimed water and be sure to incorporate the results into your landscape nutrient management plans. (Learn how here.) Occasionally, reclaimed water contains elevated levels of salts that can harm sensitive landscape plants. Azaleas (Rhododendron sp.) and crape myrtles (Lagerstroemia sp.) are two common landscape plants used in Florida that are especially sensitive to high salt levels. If you live near the coast, you may also have higher than normal salt levels in your reclaimed water because of the influence of seawater. Your reclaimed water provider will have data about salt levels in your water.
Can I Use Reclaimed Water on my Vegetable Garden?
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.
What are the Benefits of Reusing Reclaimed Water?
The main benefit of using reclaimed water is that its use replaces the use of potable water. In 2009, use of reclaimed water substituted for more than 127 billion gallons of drinking water while serving to add more than 79 billion gallons back to available groundwater supplies. Using reclaimed water for non-drinking purposes extends our freshwater supplies and ensures sustainable use of a vital natural resource. Reclaimed water also reduces the cost of landscape irrigation compared to using potable water, which is generally priced higher to consumers. When used for irrigation, reclaimed water moves vertically and can recharge groundwater aquifers. Recharging our groundwater aquifers is critical because it replaces the water withdrawn to meet the needs of a rapidly growing population in Florida.
Can I Overuse Reclaimed Water?
Yes. Remember that overwatering is overwatering, regardless of the water source. If you use reclaimed water for lawn irrigation, overwatering will cause the same damage as overwatering with other water sources. Only irrigate when soil and turf conditions indicate that irrigation is necessary. As a rule of thumb, only 3/4th to 1 inch of water is needed each week for most Florida turfgrasses.
Also, nutrient (nitrogen, phosphorus) pollution may occur if the user over-irrigates the lawn because both reclaimed water that runs off on the surface and the water and nutrients that move below the root zone are lost. Maintenance of a high level of distribution uniformity in reclaimed water-irrigated sites is critical to prevent leaching and runoff of these nutrients.