Rheem Marathon Water heater Overview

The Rheem Marathon electric water heater is a non-metallic unit designed not to rust or corrode. It has a seamless, blow molded polybutene inner tank wrapped in a filament-wound fiberglass outer tank designed for flexibility to withstand pressure. The Marathon requires no anode rod to resist corrosion, while the titanium lower and copper upper elements resist lime buildup for efficient operation. The Marathon contains two and a half inches of insulation to reduce heat loss and increase efficiency. The unit is rated at .90 – .94 EF and is available in 40, 50, 50 Short, 85 and 105 gallon models. The Marathon provides an FHR of 52-104 gallons, depending on the model capacity.

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Consumer Reviews of Rheem Marathon


  • Very Satisfied
  • Somewhat Satisfied
  • Neutral
  • Somewhat Unsatisfied
  • Very Unsatisfied
  • #2 of 14 Rheem Water heater
  • 100% of customers recommended

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Rheem Marathon Water heater Reviews

"Water heater review !"

5.0 rating
Very Satisfied

I ordered this water heater about 6 months ago. It was a very speedy delivery, to say the least. So after owning this unit for six months now, I must say that I am a very satisfied customer. I was recommended this product from a family friend and I must say that I am very happy I took the gamble to try this out. I like many things about this unit, including how easy this was to install, no leaks and its been six months now of owning this unit, and a very easy guide to follow if you want to install on your own. Overall this came very fast, free shipping, and very easy install. I would highly recommend trying this product out if you are searching or in need of a new water heater because this one is a very high quality unit that won't hurt the wallet. As of now,being a six month customer with them, I have no dislikes or complaints, nothing but good things so far with them. One last thing to note is that these Marathon water heaters are also very light in weight and you will have no problem moving this to the desired location where you want to put this in your home.

Minneapolis , MN

"Rheem Marathon – Worth the Cost!"

5.0 rating
Very Satisfied

We moved into our new home 3 years ago, and whilw we noticed the traditional water heater already in the home was over 10 years old, we hoped it would last at least a year. Well, it rusted through within a few months of moving in, and let me tell you, I was not happy to have my basement flooded! We looked around, and found the Rheem Marathon series. The special thing about this water heater is, the tank is completely plastic – it can NEVER rust! Because of this, Rheem has an amazing warranty on the product that lasts as long as you are in your home! Another small plus is that the drain is actually on the bottom of the tank, unlike most water heaters where it is a spigot on the side. If you've ever had to flush sediment from your water heater, you will appreciate that the Marathon will get 100% clean quickly and easily. I will admit, the Marathon is somewhat larger than the comparable traditional heater, if space is an issue. Also, it does cost about 50% more, but I figure between that I will never have to replace it again, plus the peace of mind in knowing I will never have another rust-through, makes it worth it. It probably will be a special order from your home improvement store, I don't know how many places keep them in stock. After almost 3 years of owning the Marathon, I have no regrets.

Montgomery County, Maryland

"Good deal for a one resident home"

4.0 rating
Somewhat Satisfied

I've owned this marathon water heater for about 6 months now. I bought it on sale and for the discount I would say that this is a decent water heater. It takes little longer than I would like for it to heat up for a good shower (probably two minutes or so) but it keeps the water hot for the duration, and I usually take reasonably long showers. For a smaller home that does not have people lining up to take their morning showers, I would say that this would be a good water heater for it.


"Water Heaters are something you can't delay in buying!"

5.0 rating
Very Satisfied

My water heater which was only 5 years old, had sprung a leak in the garage and had honestly never replaced one before in my life. Living in a track home, neighbors had recent problems as well and turned me onto home depot for good prices. With a neighbors aid, we removed the old unit in 15 minutes and and replaced the new Marathon 40 gallon unit in another 15 minutes. What a difference in how fast my shower water got hot! Didn't have to wait 3 to 5 minutes to warm up anymore. And with 4 people taking showers right after each other, we don't experience running out of hot water even with the 40 gallon tank. What a dislike is how heavy they are to install but love how fast it works now.

Las Vegas, Nv.

Other Marathon Reviews

Online comments about the Marathon are mostly positive. A consumer on thetankatwaterheaterrescue.com commented on the low standby heat loss of the unit. Another consumer agreed that the Marathon is insulated well, but claims that the elements tend to burn out. Several consumers on diychatroom.com refer to the Marathon as a great unit with very little heat loss, but a few comments mention leaking vacuum relief valves and elements needing to be replaced.

Marathon Warranty

The Rheem Marathon water heater is covered by a lifetime tank and 6-year parts warranty. If the home is not owned by the original purchaser of the water heater, the tank warranty is reduced to 15 years. If used for commercial purposes, there is a 10-year tank and 5-year parts warranty. If used in an industrial setting, the Marathon is covered by a 5-year tank and 1-year parts warranty.


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