When and what to flush

Mainlines & submains

  • At the beginning of every season

  • After any damage or repair that is upstream


Drip laterals

  • At the beginning of every season

  • After any damage or repair upstream (mainlines/submains)

  • During the season, depending on water quality. This could be weekly in extreme conditions, to monthly with better conditions. Although these are time-based recommendations above, there is absolutely no “one size fits all”, so here are three considerations.


1. Water quality

The greatest determiner of flushing frequency is the quality of the water. Aquifer water is generally quite clean and only contains mineral contaminants. Being relatively clean, it requires less flushing than a system that draws water from a river or dam where there can be high quantities of organic material that encourage algae growth in the pipes.

2. Drip lateral longevity needs

Consider what the life requirement of your drip laterals is.

A vegetable crop using drip line for only one season may only require irrigation a few months of the year before the drip tape/line is recycled. Flushing is therefore not as critical.

An orchard, vineyard or a permanent subsurface drip irrigation (SDI) system is a different story. In these cases, the drip lines are expected to last many years, and flushing becomes very important to ensure the longevity of the system.

Multi-season and permanent drip installations will require a more thorough flushing regime than a single season drip installation


3. How much water will flow through the system (plant’s water requirement)?

Lastly, it is also important to look at the plant’s water requirements (irrigation application rate) as this will also vary the amount of flushing required.

The more water flowing through the irrigation system, the more often you need to flush.

To show two contrasting examples – a vineyard crop may require 6,000 m3/hectare (2.0 ac-ft/acre) per season, while an almond crop may require12,000 m3/hectare (4.0 ac-ft/acre). With more water flowing through the almond system, it’s more likely for contaminants to build up and flushing will be needed more frequently than the vineyard.

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