Marathon Water Heaters

CPI no longer offers in office purchase or warranty exchange for Marathon water heaters.

Marathon water heaters can be purchased direct from General Pacific

To submit a warranty claim please see Marathon Warranty Process

The Marathon Electric Water Heater offers these advantages:


How much more is the Marathon than a conventional water heater? +

The residential Marathon units will cost approximately 2 to 3 times more than a basic steel water heater. That is not a real comparison though, as you are comparing a lifetime warranty product against a 5 or 6 year warranty product. Installation for the Marathon is no more and sometimes less than for steel units.

Commercial units such as the 75, 85 and 105 gallon models are attractively priced. Our manufacturing process is technologically advanced and very efficient so our incremental cost between our smaller tanks and our larger ones is much smaller than that of steel tanks.

Is it worth more than a conventional water heater? +

Yes. The Marathon after a few years won’t have to be replaced. The cost of the water heater is usually only half your cost however. Installation is the other cost and you won’t have to pay for that and another water heater time after time. The other thing people often overlook is the damage to their floor and belongings when their cheaper water heater fails.

Why should I bother, my last water heater lasted 22 years? +

That’s impressive but not uncommon for older water heaters. Older water heaters had much thicker steel and more porcelain than today’s units. Because manufacturers have cut so many costs from the manufacturing process, most steel water heaters made today will not last much longer than their warranty.

What size water heater should I buy? +

The first limitation is the heaters physical size and the space available for installation. If space is not an issue you can use this guide to help determine your Peak Hour Demand which is the key to sizing your water heater.

Product Specifications

All units come complete with a factory installed temperature and pressure relief valve, replaceable brass drain valve, and vacuum relief valve.

ModelCapacity (gallons)ElementDiameter x HeightTank Weight
MR30245304500 W21 5/8″ X 49 1/2″75 lbs
MR40245404500 W21 5/8″ X 65 1/2″90 lbs
MR50245504500 W23 1/2″ X 66 3/4″100 lbs
MSR5024550 short4500 W28 1/4″ X 47 1/4″95 lbs
MHD75245*754500 W28 1/4″ X 62 5/8″122 lbs
MHD85245*854500 W28 1/4″ X 70 1/4″134 lbs
MHD105245*1054500 W30 1/4″ X 70 3/4″152 lbs
*Light Duty Commercial


Residential Warranty

To submit a warranty claim please see Marathon Warranty Process

YOUR MARATHON TANK IS WARRANTED NOT TO LEAK FOR AS LONG AS YOU OWN YOUR HOME… Marathon offers this no-leak promise because of its superior, non-metallic PermaGuard tank construction – a seamless blow molded polybutylene tank with a filament wound fiberglass outer tank for maximum strength. Superior performance, high-efficiency, and low operating cost…for a lifetime!

(*10 year warranty is upgraded for free after a simple online registration. Please see your owner’s manual for more information.)

Agricultural and Business Warranty


When you buy a Marathon water heater for these demanding applications, you are buying long term efficiency and peace-of-mind. Whether you are dealing with the high moisture and demand of agricultural applications, temperature extremes of commercial sites, or the multiple installations of a lease program, the Marathon is the long distance performer. With a proven track record in these environments, Marathon water heaters installed in these applications are warranted not to leak for a period of 5 years*

Parts Warranty

Component parts of the Marathon water heater such as the thermostats and elements are warranted for a period of six years from date of manufacture for all residential applications after a simple online registration, and of one year from date of installation for agricultural applications.

Installation Tips

Maintenance Tips