Utilities · Application

Reservoir covers

Reservoir evaporative loss is equivalent to 20% of the global annual consumption of water (Zhao et al., 2022).

On the water

Floating WaterPearls mats form a complete evaporation cover over the reservoir.

A cover that stays in place, permeable to rain and air.

77–98%

Evaporation reduced

Long service life

Low maintenance

Field documentation

Measured in the field: 91% lost uncovered, 2% under WaterPearls.

A side-by-side pan-evaporation trial near Johannesburg, South Africa (28 Nov – 23 Dec 2015 · 25 days · one 8 mm rain event). An uncovered control pan lost 91% of its water to evaporation; a pan under four layers of WaterPearls lost just 2%.

91%

Evaporated from the uncovered control pan

Evaporated under 4 layers of WaterPearls

~98%

Evaporation suppressed at 55 mm bead depth

Cumulative-evaporation and suppression-vs-bead-depth measurements, RHST field trial, Johannesburg S.A., 2015. In this single trial, suppression increased with bead-layer depth, up to ~98% at the deepest layer.

How it works

A complete floating cover.

Mesh mats

Thousands of WaterPearls are inserted in 45 cm × 100 cm mesh mats, in options of 2 to 4 layers.

Installed on the reservoir

WaterPearls mats are installed on the reservoir, forming a complete cover.

Repel water

Just like a lotus leaf, the WaterPearls repel water.

Performance

Stop the loss at the surface.

Reduce water evaporation by 77% to 98% depending on the number of layers of WaterPearls in the mats
Limit algae growth
Help limit bromate formation by reducing light and algae growth
Insulate the water body
White surface reflects sunlight to keep reservoir water cooler

Cumulative daily evaporation: the uncovered control pan loses ~13 cm of water over 25 days while pans under WaterPearls layers stay near flat — Cumulative evaporation: control vs. WaterPearls layers

Evaporation suppression rising from ~40% at 14 mm bead depth to ~98% at 55 mm — Suppression vs. bead-layer depth

How it compares

Built to outlast the alternatives.

Most evaporation covers trade one problem for another. WaterPearls are engineered to avoid the trade.

Shade balls

Plastic, and a 10-year replacement cycle.

HDPE spheres carry a high production water footprint and are typically replaced about every decade. WaterPearls have a long service life with a far lower production footprint.

Chemical films

Slow evaporation by roughly a third, but only for days.

Mono-layer surfactant films are wind-sensitive and degrade within days, needing constant re-dosing. A WaterPearls cover stays in place and is permeable to rain and air.

Biological covers

Modest savings, real water-quality risk.

Floating plants cut evaporation only modestly and can deplete oxygen in the water. WaterPearls suppress evaporation while limiting algae and bromate formation.

Benefits

Engineered to float and last.

Long service life
Mats are permeable to water, so rain flows through
Mats are permeable to air, avoiding oxygen depletion in the reservoir
Floats and stays in place in the reservoir
Non porous to prevent absorption of water in the WaterPearls and harbouring of bacteria
Very low production water footprint in comparison with shade balls