Floating covers prevent algae at the source by blocking light (95%+ suppression, no power, no operating cost); UV treatment kills algae and pathogens downstream of the reservoir at point-of-use, with continuous power and lamp replacement costs.
At a glance
| Metric | Hexagonal floating cover | UV treatment |
|---|---|---|
| Where it acts | At the water surface (prevention) | Inline at point-of-use (kill) |
| Power consumption | Zero | Continuous |
| Lamp replacement | Not applicable | Annual |
| Algae prevention vs disinfection | Prevention | Disinfection |
| Evaporation reduction | 90–97% | None |
| Lifecycle | 25+ years | 10–15 years (with periodic lamp replacement) |
For potable water utilities, floating covers and UV treatment are complements, not alternatives. Covers prevent algae from forming in storage; UV disinfects at point-of-use. Most modern designs deploy both.
What each does
Floating covers stop algae at the storage reservoir by blocking the sunlight that drives photosynthesis. They also reduce evaporation and odor. No power, 25-year lifecycle.
UV treatment uses ultraviolet light at the point of distribution to kill microorganisms (including residual algae and pathogens) that have already formed. It does not prevent formation; it disinfects.
Complementary design
- Cover the storage reservoir → algae load on the UV system falls 95%+.
- UV disinfection at distribution → handles the residual + meets disinfection compliance.
The combined design reduces UV operating cost (lamp life, energy, cleaning frequency) because the algae load is much lower at the UV inlet.
When UV treatment makes sense
UV treatment is appropriate at point-of-use for pathogen disinfection in drinking water systems where residual chemical disinfection is supplemented or replaced. It addresses what reaches the customer; it does not address what grows in the storage reservoir. Both are complementary.