Solar Water Trough

With an outside water tank in your horse’s pasture, winter can mean learning to use an ax or sledge hammer to break ice in the water tank every day and then shovel it out. 

The manual-fill tank was just the ticket, since our priority was ensuring palatable water year round.

Sure, there are electric heaters and anti-freeze devices – and they will work – but we’ve always shied away from using them around horses, unless absolutely necessary. We needed something that would keep the water from freezing without anything a horse can get into trouble with.

So, we were intrigued – but skeptical – when we saw the Solar Water Tank. It’s made of a hard plastic/rubber shell with a shatter-resistant sun panel on the front. The horses drink out of the top, pushing down a bob cover, which our horses quickly learned to use. It kept the water cool in the summer and warm in the winter.

We set the tank up so the solar panel faces south, per the instructions (it would be easier to do if the tank had a simple compass built into its top, but we used a pocket compass). We were sure that if the tank was designed to keep the water warm in the winter, it would likely become hot in the summer. In fact, we were so concerned that we didn’t even put the tank out with the horses in the warm weather until we were convinced it wouldn’t make the water hot.

Mark Ames, the manufacturer, explained, “The reason why the water is not warming is the solar panel is angled to work only when the sun is lower in the sky, like in the winter time, when the sun is low in the sky and striking more perpendicular. it’s like when you shine a flashlight, if you point it straight all the light is concentrated on one round spot, but if you angle the light where it’s spread out, less light hits with little concentration, which means less power to heat. The idea is to keep the water cool in the summer for livestock.”

During the summer, the sun is mostly overhead, not concentrating on the solar panel, he said. “As the days go by toward winter, the sun will sit lower in the sky. Another example is if you look straight into the sun (but don’t do that), it has blinding light, but as you turn away it has less direct sun rays with less power. In the winter the sun hits a more straight direct path into the solar panel and keeps the water from freezing.”

The tank comes with a white rugged-fabric cover that fastens to the tank and stops the sun from hitting the solar panel. We did not have to use this, but in some areas the manufacturer states it may be necessary. The alternative is simpler: When the weather gets warm, turn the tank around so the solar panel faces north.

Cold Weather

When the cold weather hit, we filled our steel tank as well, so we could compare the two tanks. The full steel tank of water froze when the temperature hit 27°, while the SunTank had absolutely no ice on it at all. That didn’t mean we didn’t have to do anything, though.

Every winter morning we removed any snow from the top of the tank and any ice that might have formed between the edges of the bob and the tank. A few brutally cold mornings, it took a couple of whacks with our rubber hammer to loosen the bob, but we never saw ice in the tank water. It was always in the tiny section between the bob and the edge. We cleaned off any ice sticking to the edges of the bob, filled the tank with water, and replaced the bob. This took maybe five minutes, even on a 13° morning. We also shoveled away any snow that might block the solar panel.


It’s available with an auto-fill and shut-off float feature to hook up a garden hose, but we chose the manual fill because our main concern was winter, and we would not be able to leave a hose outside. It’s also available as a 42-gallon tank. The manufacturer states the 42-gallon unit will work to -50°, and the 25-gallon to -20°. This includes winter conditions and wind-chill. It costs from $573 for a manual-fill 25-gallon tank to $683 for the auto-fill 42-gallon tank, plus shipping (

Bottom Line.

The manual-fill 25-gallon SunTank works, and we prefer it over electric-based tank heaters and galvanized steel. The original one has been in use for five years now, and shows little wear. We bought a second one a few years later, and it is also performing well.

Our horses had no problem using the tank, and we introduced the concept by leaving off the bob top initially, then adding it back after a few days. The tank also withstood quite a bit of chewing and horse play.

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