However, once primed and positioned correctly, they will continue transferring water from the source to the destination.
The simplest siphon tubes are operated by simply filling the tube with water (by immersion in the canal, or other means), keeping one end in the canal and with the other end sealed, placing it in the area to be irrigated.
For tubes of up to 150mm diameter and several meters long, this is all easily undertaken by one person without any other tools.
The main benefit of siphon tubes is that they are relatively inexpensive, and do not require any engineering to put into place (unlike say a sluice gate embedded in the bank of the canal).
They are easily relocated from one bay or field to another as the required water level is reached.