By Lorne Haveruk, C.I.D., C.I.C.,
C.L.I.A., Diamond Head Sprinklers Inc. and Water Management Services Inc.
As clean fresh water sources continue to be overtaxed, focus for irrigation water will turn to "Reclaimed Water." Reclaimed water is water that has already been used once and is then recycled and depending upon the source, treated so that it can be put to beneficial use once again. Collection of rainwater into holding tanks, called cisterns if held in the ground, has been in existence since the Romans colonized Pompeii. This may be among the purest forms of water currently available for irrigation use, requiring minimal treatment. Tertiary water, which is treated sewage water, requires sophisticated treatment and would limit access where irrigation occurs.
Reclaimed water has been used on landscapes and agricultural crops in regions where a moisture deficit has occurred during the growing season. Designing and operating irrigation systems to make beneficial use of reclaimed water makes good sense, when you hear about all of the new water problems occurring daily, both locally and around the globe.
Any source of used water, of which there are more than a dozen, comes with many regulations and guidelines to ensure public safety. Currently permitted uses are allowable only when using reclaimed water. Before venturing too far forward into this newly evolving area of water use, check all local bylaws that may or may not allow the use of reclaimed water. As the pressure for clean water increases, reclaimed water use will become the accepted norm for supplied irrigation water.
Two areas of concern are "Restricted Public Access," where the public is to be restricted from access in which reclaimed water has been used at any time during or after application.
"Unrestricted Public Access" allows the public access due to the high quality level of the reclaimed water.
Where reclaimed water is used for golf course irrigation, nurseries, or other publicly attended areas, the reclaimed water will need to be properly treated and filtered to remove contaminants and debris that may clog irrigation system components. Dirty water valves and flow-through sprinklers might be required if particulate is still present in the water after filtering.
There are specific makes of irrigation components that can be put together to create systems for use with reclaimed water. For unrestricted public access, sprinkler and/or drip irrigation can be used on agricultural crops. For turf and landscape applications, pop-up sprinklers and spray heads or drip or trickle can be used. Restricted public access areas are allowed to use sprinkler irrigation for forage crops with drip or trickle systems for vineyard or orchard crops, while vegetables must be irrigated using subsurface systems.
Management of a reclaimed water system is very important. Safety measures must be undertaken to ensure operational and maintenance personnel health requirements are met. Areas of use must be properly signed, restricting access into the irrigated areas to authorized personnel only. Water storage must be considered to ensure enough reclaimed water will be available for irrigation during the dry weather periods. Consideration must be given to excessive amounts of water during wet weather periods and how overflow or discharge of the reclaimed water will be handled.
Many considerations must be dealt with prior to implementing a reused water project. The benefits outweigh the additional considerations required to use reused water. In the future as clean water becomes more restricted as to its allowed uses, reclaimed water may be the only source of water for irrigating larger sites. Already this spring in parts of Canada watering restrictions are in place, prohibiting irrigation due to the low snow pack combined with below normal rainfall. If reused water were available, would the restrictions have been necessary?
