They are the ones that have as their objective, the assurance in case of emergency, that they are going to work with the pressure and volume required while the operation of fighting the fire last.

Their main components are:

Water feeding source: It has to be able to supply the required volume and pressure of water during the stipulated time. May or may not need a discharge system if by itself can assure the needed pressure condition. Generally, private supplied tanks or outdoor public networks are used.

In case of water reserve tanks the following fundamental aspects must be watched:

1. That they are used exclusively for fire extinguishing.
2. That they are refilled automatically in a maximum time period of 24 hours.