A geothermal energy installation and system, in which the field of potable water is utilized by a secondary conduit system to route potable water from an inlet in the user's line coming from the potable water field but upstream of the user's meter, through the heat exchanger equipment of a user, and back to the field at a point upstream of the final treatment processing stage of the field. Thus, the thermal energy of the water of the field is utilized without adding the cost of the volume of potable water use by the user, and is re-processed if somehow contaminated in the secondary conduit systems; and although the secondary conduit system delivers water back to the field at a changed temperature, depending upon the heat exchanger effect, the relatively large volume of water of the potable water field assures that the returned water does not even substantially alter the temperature of the potable water field.