You do not need a resource consent for everything. A consent is not required to take freshwater for stock or for fire-fighting, providing these activities have no adverse environmental effects.

Your activity could also fit into the category of being a permitted activity. These are generally minor in nature and can be carried out under authorisation set out in regional plans. These authorisations are often subject to conditions. If your activity cannot meet these conditions you will require a resource consent.
Examples of activities which may be permitted in the Canterbury region include:

the discharge of sewage tank effluent into the ground (subject to conditions)
the minor discharge of animal effluent onto land (subject to conditions)
the taking of minor quantities of groundwater and surface water (subject to conditions).

If a proposed activity is a permitted activity, you may request a certificate of compliance from the regional council which will state it complies with the relevant authorisation (and conditions if specified) set out in a regional plan.