A floating cover is the most cost-effective way to reduce evaporation, algae, and odor on industrial water bodies — typically delivering payback within 18–36 months on water savings alone [USDA Bureau of Reclamation] .
What is a floating cover?
A floating cover is a buoyant surface barrier deployed on reservoirs, tailings ponds, digesters, process water tanks, and irrigation storage to suppress evaporation, photosynthesis-driven algae, volatile odor emissions, and heat exchange with the atmosphere. The modern industrial form is a modular tessellation of self-ballasting HDPE elements — hexagonal panels or armor balls — deployed without anchors and without draining the water body [AWTT — original Hexprotect® patent, Hexprotect® AQUA (pre-ballasted variant)] .
How floating covers work
Floating covers reduce open-water losses through three mechanisms:
- Surface coverage physically blocks evaporation by limiting the water-air interface.
- Light blocking suppresses photosynthesis, the prerequisite for algae bloom.
- Insulation reduces heat transfer with the atmosphere, retaining process heat in hot wells and reducing freeze risk in cold climates [US DOE recognition] .
Benefits of floating covers
| Metric | Hexagonal cover (AWTT Hexprotect® AQUA) | Source |
|---|---|---|
| Surface coverage | 99% effective | AWTT |
| Evaporation reduction | up to 95% | AWTT |
| Sunlight blocking (algae) | 99% | AWTT |
| Wind resistance | 130+ MPH (209+ km/h), certified | AWTT |
| Life expectancy | 25+ years | AWTT |
| Manufacturer warranty | 10 years | AWTT |
When to use a floating cover
Floating covers are appropriate when any of the following apply:
- Operating water cost is > €0.50/m³ and surface area > 1,000 m²
- Algae-related operational costs (filtration, chemical treatment, downtime) are recurring
- Regulatory pressure on emissions (H₂S, VOC) requires odor capture
- Heat-loss budgets affect process economics (district heating returns, biogas digesters)
- Drinking-water reservoirs need NSF/ANSI food-grade evaporation suppression
Floating cover vs. shade mesh
Shade mesh blocks sunlight and reduces algae but is permeable to vapor — so it does not stop evaporation. Hexagonal covers block both. See hexagonal vs. shade mesh for the full comparison.
Sources and further reading
- FAO Irrigation and Drainage Paper 56 — reference evaporation rates
- USDA Bureau of Reclamation — evaporation suppression field trials
- US Department of Energy — wastewater facility cover evaluations
- EU Water Framework Directive — regulatory context for EU operators