Do Shade Balls Actually Save Water?

Yes — hollow plastic ball covers genuinely save water. Evaporation happens at the air-water interface, and a dense floating layer of balls removes most of that interface. Armor Ball® covers about 91% of the surface and cuts evaporation by up to 90% per AWTT published data.

Why a ball cover cuts evaporation

Two forces drive evaporation from open water: solar energy heating the surface, and wind carrying away humid air just above it. A close-packed layer of 100 mm (4 in) balls attacks both:

• It shades the water, so less solar energy reaches the surface to drive evaporation.
• It breaks up wind at the surface, slowing the removal of the humid boundary layer.
• It physically covers 91% of the area, leaving only the small gaps between spheres exposed.

What the numbers look like

An uncovered 5-acre pond can lose over 1,000,000 gallons of water a year to evaporation in a hot, dry climate. At up to 90% reduction, a dense cover keeps the large majority of that water in the pond — water you don’t have to buy, pump, or replace.

Use the evaporation & water-loss calculator to estimate the savings for your own surface area and climate.

The honest caveats

• Coverage density matters. Savings scale with how completely the surface is covered; a partial scattering of balls saves far less than a full 91% layer.
• Climate matters. The hotter, drier, and windier the site, the larger the absolute savings — arid regions see the most.
• Rain still gets in. The balls let rain and snow pass through, so they reduce evaporative loss without blocking inflow.

Beyond water savings

Because the same cover also blocks UV, it suppresses algae and limits sunlight-driven reactions like bromate formation, while cutting odor and heat loss. So the water saved is only part of the return — see how it works and the Armor Ball® specs.

Learn more: What are shade balls? · Evaporation control · Lifecycle cost