Water quality can have a negative effect on the performance of an irrigation system due to plugging of emitters and sprinklers. Problems can be caused by inorganic solids (silt and sand), organic solids (algae, bacteria, slime) and dissolved solids (calcium, iron, manganese). Potential problems can be minimized by testing your water so you are aware of potential issues. Filtration is the primary requirement for all drip systems to remove any suspended solids. This can be accomplished with one or multiple filtration methods depending on the water quality issue. In some cases, chemical water treatment may also be required to maintain uniform water application. Chlorine is the treatment chemical used to control microbial growth, decompose organic materials, and oxidize soluble minerals. Potassium permanganate can also be used to oxidize iron. Oxidation will cause minerals to precipitate out of solution so filtration must follow treatment. Acid treatments can be used to lower water pH to maintain solubility of minerals or to dissolve mineral caked around emitters. Equipment for water treatment is similar to chemigation equipment. Filtration should always follow any water treatment to remove any precipitates.
The following bulletins will provide additional information to help you decide what type of treatment will work best for your situation.
Management of Iron in Irrigation Water, X. Shuai, G. Zinati, Bulletin FS516, Rutgers Cooperative Extension, 2005
Recommendations for the Control of Iron in Drip Irrigation Systems, Netafim USA, Fresno, CA
Dealing with Iron and Other Micro-Irrigation Plugging Problems, T. Obreza, E. Hanlon, M. Zekri, Bulletin SL 265, University of Florida Extension, 2014.
Treating Irrigation Systems with Chlorine, K.W. Migliaccio, B.Boman, G.A. Clark, Bulletin CIR1039, University of Florida Extension, 2009.
Drip Chemigation: Injecting Fertilizer, Acid and Chlorine, D.M. Granberry, K.A. Harrison, W.T. Kelley, Bulletin B 1130, University of Georgia Cooperative Extension, 2012
Shock Chlorination Treatment for Irrigation Wells, D.H. Rogers, F.R. Lamm, M. Alam, G.M. Powell, Bulletin MF-2589, Kansas State University Extension, 2003.
Subsurface Drip Irrigation Systems (SDI) Water Quality Assessment Guidelines, D.H. Rogers, F.R. Lamm, M. Alam, Bulletin MF-2575, Kansas State University Extension, 2003.
Iron Bacteria Problems in Wells, Publication DG-004-2015, Wisconsin Department of Natural Resources. – Publication has guidelines for amount of Chlorine to use for shocking a well on page 2.
Irrigation Water Quality Standards and Salinity Management Strategies, Guy Fipps, Bulletin B-1667, 17 pg., Texas A&M AgriLife Extension, 2003.