Marathon Lifetime 50-Gallon Electric Water Heater

The Marathon Lifetime 50-Gallon Electric Water Heater is the standalone Marathon brand variant of the Rheem Marathon line. Marathon is Rheem-owned but sold through both Rheem channels and as standalone Marathon-branded inventory through specialty water-heater dealers. Same polybuthylene-tank engineering, same lifetime tank warranty.

Specs: 50 gallons stored, two 4500W heating elements, UEF 0.93, 62-gallon first-hour rating. Polybuthylene fiberglass-reinforced plastic tank — cannot rust through. Lifetime tank warranty (transferable to subsequent homeowners), 6-year parts warranty. NiCu-coated heating elements (higher quality than standard copper elements) reduce scaling in hard water.

The Marathon's defining feature is the polybuthylene tank construction. Unlike glass-lined steel that fails by rust-through at year 10-15 in most water conditions (much shorter in hard water), the Marathon tank has no iron to oxidize. Real-world Marathons from the early 1990s are still in service 30+ years later.

The economic case: $1,899 unit, $2,500 installed — versus $599 / $1,100 for a standard Rheem Performance 50-gallon electric. Break-even at year 11-13 for typical service life; significantly faster in hard-water regions where standard tanks fail at year 7-9.

Right buyer: forever-home owner, particularly in hard-water regions. Wrong buyer: short-term residence (under 8 years), basement install that could accommodate a heat-pump (ProTerra operating-cost advantage outpaces Marathon's longevity advantage).