Tank: The tank of the WaterRower M1 LoRise is made from polycarbonate, one of the strongest plastics available. It is virtually indestructible. The tank is sealed and can be filled with municipal water via a small opening closed by a stopper. This water typically contains enough chlorine to remain clear for some time. After exposure to light, the chlorine will degrade and the chlorine tablets included free with the WaterRower M1 LoRise should be added periodically.
The machine was easy to put together and worked well mechanically. The problem is the electronic monitor. The strokes/min registered as double the actual pace, and the distance registered as 1/10th the actual distance. I contacted customer support via email and their response was slow and inadequate. I am returning the machine and plan to buy a WaterRower.

I kayak (ocean and flat water, not river), so I was drawn to the WaterRower over a flywheel type rower (which I have used in gyms) because I wanted to hear the sound of the water, which I miss hearing against the hull of the boat during the winter when I can't get out on the lake. I also like the way the paddles engage in the water; it's a very smooth pull and release, and moving the mass of the water instead of a dialed down tension feels more natural. As someone else also commented, the seat (at least on the wood version) is incredibly smooth and solid; no wobbling at all. I generally listen to music on my Nordic Track ski machine, but with the WaterRower I am content to listen to the sound of the water; working out on this is somehow both energizing and calmingly meditative at the same time. In the event that you want to use it while watching tv (this is one use to which I wanted to put it), it is quiet enough to hear the tv without having to turn it up.

The WaterRower Natural is handcrafted in solid ash and stained honey oak for consistency of color. The wood was chosen due to its marvelous engineering properties, especially its ability to absorb sound and vibration, which enhances the WaterRower's quiet performance and smooth operation. Ash, like all woods used in the construction of the WaterRower, is a premium hardwood with incredible longevity and dimensional stability. In addition, the wood is harvested from replenishable forests and is hand finished with Danish oil to provide a deep luster.
Other details include dual rails with four corner wheels that increase seat stability and reduce the amount of sweat buildup; a frame that flips upright for handy storage; and a weight capacity of up to 1,000 pounds. The WaterRower Natural measures 84 by 21 by 22 inches (W x H x D), weighs 117 pounds (with water), and carries a one-year warranty on the frame and components (WaterRower will upgrade the warranty to five years on the frame and three years on the components with the completion of a registration form).
There is much to love about the WaterRower--and I do love it--but I would echo others' comments that although the seat rolls solidly and smoothly on the wood rails, the seat itself is very hard (I use a gel seat pad I bought for my hard fiberglass kayak seat), and the footpads are in need up rethinking and upgrading--the cheap plastic doesn't let you row in socks or barefoot and is not really worthy of a machine that is otherwise a stunning piece of engineering and a beautiful one as well. As one other person noted about his machine, my machine made a clicking noise on the return stroke, so I had to adjust the wheel underneath the top rail that connects to the footpad and pull it away gently from where it was rubbing against another component. Also, be warned: the instruction booklet is in the DVD case. I did not see the little sticker on the case telling me that, thinking I'd wait to watch the DVD until after I'd assembled it. But WaterRower has a copy of the assembly instructions on their website, along with a video (I found the written ones better and easier to follow), so I was able to assemble it with no difficulty.
Proposition 65 requires businesses to provide Californians with a clear and reasonable warning about chemicals in the products they purchase, in their home or workplace, or that are released into the environment. By providing this information, Proposition 65 enables Californians to make informed decisions about protecting themselves from exposure to these chemicals. Proposition 65 also prohibits California businesses from knowingly discharging significant amounts of listed chemicals into sources of drinking water.
The Verified Sustainable Hardwoods used for the WaterRower are sourced from the Appalachian Mountain region of the eastern United States, where planting rates exceed harvest rates by an average multiple of 2.29. The Appalachian Hardwood Timber resource includes more than 65.4 million acres in the eastern United States and provides the world with a bounty of the finest hardwood species.
Our Wooden Rowing Machines are Made in the USA using hardwood from only replenishable sources. We strive to manufacture rowing machines that are of a stylish design and built to last, while maintaining our commitment to eco-friendliness. Our Rowing Machines are functional fitness furniture, designed not to be hidden away like other unsightly gym equipment, but to look at home in your living room. Storing in an upright position no wider than a dining room chair, our rowing machines can be easily laid out for a quick indoor rowing exercise session. 
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