Water Sampling Guidelines. Part 1 To obtain good results in the irrigation water analyses it is really important and necessary follows up the guidelines below to the samples could be taken properly. Irrigation water origin: It may be irrigation water whatever its origin: bore holes, rivers, ponds, etc .. Time of year to take sample: It can be done at any time of year How to take the sample: • The samples must be collected into the glass or inert plastic container and should be clean. It is recommended to wash the container several times. • If water is for potability analyses a sterile container should be used.