IRRIGATION: TESTING WATER SUPPLY

The water supply for an irrigation system should be tested. Testing involves determining the flow rates produced against different pressures. If a flow meter is not available, a graduated bucket and a stop watch can be used to determine the flow rate.

The pressure of municipal water supplies fluctuates during the day. During the times of low water demand, such as late night or very early morning hours, the water pressure is much higher. This time may be the best for operation of the irrigation system.

Water quality of the water source may affect the design of the irrigation system. In general, water quality problems can be classified as:


Physical problems relate to mineral particles of sand, silt, and clay present in water sources.
Chemical problems associated with high levels of soluble salts, calcium, magnesium, bicarbonate, iron or manganese which can precipitate from the water causing clogging or undesirable staining, or low pH (acidic water) which can corrode metal parts.
Biological problems (shallow wells and surface waters) are quite often encountered in the presence of various microorganisms, algae, and fungi can create maintenance problems in irrigation systems.


If the water for a home irrigation system is from a municipal line, then water quality should not be a major problem. Filtration may still be necessary for some systems, but the type of selected filters may be much simpler. Filtration and sometimes water treatment may be necessary depending on the type of irrigation system used and the water source (well, pond, river or canal). Sprinklers can be damaged by physical contaminants such as sand and silt.

In general, water to be used in a micro-irrigation system will require filtration and often additional treatment. Even with city water a 200-mesh filter is recommended. Clogging problems will vary with and within the sources of irrigation water.

For more information and charts go to: http://edis.ifas.ufl.edu/WI003
Irrigation of Lawns and Gardens. Dorota Z. Haman, Gary A. Clark, Allen G. Smajstrla. Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Publication date: May 1989.