Shade Balls: Sustainable Drought Prevention

Shade balls are plastic spheres used for slower evaporation in bodies of water and for environmental protection purposes. The small balls cover the top of a body of water, usually a reservoir, to help slow the evaporation process and retain the water supply. In addition, they provide a number of other benefits to the water and its surroundings.

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What Shade Balls are Made of

High-density polyethylene makes up a shade ball, which is what is also found in gallon-milk containers, for example. Filled with water to weigh them down, the balls rest on the water’s surface and won’t get blown away with the wind.

Carbon black is added to the makeup of the ball to stabilize the shade balls under UV rays from the sun. This carbon black addition prevents bromate from forming, which is a chemical reaction occurring when sunlight and the water’s bromide and chlorine mix.

Groundwater naturally has bromide, and the chlorine found in some reservoir water is used to kill bacteria. Add sunlight to the mix and you get bromate, which can cause adverse stomach reactions when people drink the carcinogen-filled water.

So, shade balls can help prevent this from happening by protecting the water supply from harsh sunlight.

What Shade Balls Do

Not only do they protect the water from sunlight, they also serve as a barrier against wildlife. To help prevent feces from getting in the water, the shade balls are closely packed together to form a unified barrier.

They also protect against dust, rain and the formation of algae. Primarily, shade balls are used in reservoirs to help slow the process of evaporation. By providing protection from the heat and sun, the water is retained within the reservoir, ready to be used for human consumption.


Shade balls can last about a decade before needing to be replaced. At the time of removal, they can easily be recycled, making them a more environmentally friendly option than other materials like tarps.

They are also more cost effective than tarps, running about 40 cents a ball or less. The balls’ role in retaining reservoir water also provides sustainability to the local city or town it directly impacts, as well as the surrounding locations water would normally be drawn from in the case of a water shortage.

Where Shade Balls are Used

Considering evaporation causes the loss of more water than human consumption in reservoirs, these bodies of water are the most common use for shade balls at this time. This is also because of their amazing protective and preventive properties against wildlife, chemical formations, and more.

The Los Angeles Reservoir is a great example of shade balls being used to protect a water supply in both quantity and quality. In 2014, the reservoir got its first batch of shade balls, with the final installment in August 2015 for a total of 96 million shade balls.

The massive amount of 4-inch-diameter balls are in place with the LA Department of Water and Power hoping to save 300 million gallons or more of water each year. Multiple other reservoirs in California also use shade balls in an effort to save water, especially in times of drought.

Shade balls can also be used on toxic bodies of water in an almost opposite way than their use on reservoirs. In toxic situations, the balls covering unclean water keep out animals, protecting them from the unsafe environment.

Interested in joining the effort in water conservation? See how many shade balls it will take to cover your body of water and click the link below.

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