OEM Replacement Fresh Water Tank for 2015 Airstream Interstate EXT

The reported 602184 number, 12 by 12 by 48-inch dimensions and 26-gallon capacity are identification leads from the question, not a verified replacement specification. An exact current OEM replacement for this particular 2015 Airstream Interstate EXT has not been confirmed here.

Confirm the coach's exact build and installed tank markings with Airstream or an authorized Airstream parts dealer. Provide the VIN privately through that service channel, along with clear photos of the tank numbers, complete shape, molded recesses, hanger/support arrangement and every fill, vent, outlet and drain connection. Compare the exact part/revision drawing rather than selecting a similar-capacity rectangular tank.

The question reports molded hanger-bolt indentations and an attached heater pad. Their geometry, attachment and electrical requirements must be checked on the actual installation; an attached pad does not establish that a replacement tank includes a pad or that an old pad can be transferred. Confirm the tank, heater pad, wiring, supports and any separately supplied fittings as individual items.

Use Airstream's owner's manual and parts-book index to locate the exact model documentation, and have the part/revision and current replacement availability verified before ordering. If access underneath is needed, use an RV service facility with appropriate lifting equipment. No fit guarantee, heater inclusion, current supersession, stock, sourcing outcome or shipment is promised by this answer.