A jacket for a hot water heater appliance includes a top, bottom, front, back, and a fastener. The top is configured to insulate an upper portion of a hot water tank. The bottom is configured to insulate a lower portion of the hot water tank. The front is configured to insulate a front portion of the hot water tank. The back is configured to insulate a back portion of the hot water tank. The fastener is configured to releaseably fasten the front to the back. The top, bottom, front and back include expanded polypropylene (EPP) configured to provide insulation to the hot water tank.