Water quality is an important consideration when choosing an irrigation system. Drip systems require very good water quality. When using sprinklers, fine mechanical and organic impurities are not a problem, larger aggregates will be "captured" by coarse mesh filters. Drip irrigation requires thorough filtration of solid elements contained in the water and, in the case of water with high Fe and Mn levels, also treatment. Due to their specifics - small diameter of sprinkler nozzles and small size of labyrinth channels placed in drippers, micro-irrigation systems require very good water quality. Iron or manganese content in the water above 1-1.5 mg/l already poses a very high danger of clogging of drip emitters and requires de-ironing. Practically there is no problem with clogging of emitters with iron content below 0.5 mg/l. In installations where the emitters are mini-sprinklers, even several times higher Fe or Mn content in the water is not yet a problem (Table 4).
Drip emitters can also be clogged by fungi, bacteria and algae developing in the system. which, in favorable conditions, multiply to form a characteristic slimy mass blocking the drippers.
Algae growth at the outlet of the drip emitter
Table 4: Evaluation of water quality for drip irrigation.
| Parameter | Low probability of clogging the emitters | Medium probability of emitters being clogged | High probability of clogging the emitters |
|---|---|---|---|
| Solids content [mg/l] | < 50 | 50 - 100 | > 100 |
| pH | < 7 | 7,0 - 8,0 | > 8,0 |
| Dissolved sub. content [mg/l] | < 500 | 500 - 2000 | > 2000 |
| Manganese [ppm] | < 0,1 | 0,1 - 1,5 | > 1,5 |
| Iron [ppm] | < 0,1 | 0,1 - 1,5 | > 1,5 |
| Hydrogen sulfide [ppm] | < 0,5 | 0,5 - 2,0 | > 2,0 |
| Bacteria [number/ml] | 10000 | 10000 - 50000 | 50000 |