Water sources for drip irrigation can include municipally treated water, well water, pond or reservoir water, and ditch, stream, or river water. Clean water is especially important to successful drip irrigation. The small orifices found in all drip emitters can be clogged easily by physical and chemical contaminants found in the water. Groundwater from wells is generally of good quality and should be used when possible. Groundwater may contain sand or chemical precipitates. Surface water can be used but often contains bacteria, algae, and other aquatic life. In any drip installation a screen filter or disc filter and chemical treatment of surface water is generally required. Usually, fast moving water contains higher levels of suspended particles, and reservoirs or ponds contain a relatively small amount of these particles. For small drip irrigation operations, the water source does not have to be excessively large. Most small systems require only 2 to 5 gallons per minute per system and can use a 3/4" to 1 " filter and a small fertilizer injector
Algae and mold
To clean a drip system from algae and mold you can inject chlorine (household bleach-sodium hypochlorite or swimming pool chloride-calcium hypochlorite) during the last 30 minutes of an irrigation cycle (or time required to fill all lines) so that 1 ppm of free residual chlorine remains at the end of the line. 1 ppm is equal to 2.6 ounces of household bleach in 1,000 gal of water.
Sodium hypochlorite is preferred over calcium hypochlorite for hard water to reduce calcium carbonate precipitation in the lines. Keep the pH down to 7.0 by using a metering pump or one of our injector to inject an inexpensive acid like a food grade phosphoric acid. Acid injection for a short duration, followed by a rinse period, this material has not been found harmful to drip system. The frequency of this treatment will depend on water quality and contaminant levels.
This information provided by the North Carolina Cooperative Extension Service