How much water does a reservoir actually lose through evaporation (and how to calculate it for free)
How much water does a reservoir actually lose through evaporation (and how to calculate it for free)
Introduction
In agriculture, mining and other industries, water is an increasingly scarce and valuable resource. However, thousands of liters are lost every day due to a phenomenon as silent as it is costly: evaporation.
The most worrying thing is that most farmers and operations managers don't realize this loss until they do the calculations.
In this article, we'll show you:
- How much water actually evaporates in a reservoir.
- How to calculate water loss in your own operation with a free tool.
- What solutions exist to reduce evaporation in irrigation reservoirs and reduce evaporation in mining reservoirs.
How much water evaporates in a reservoir?
Evaporation depends on factors such as solar radiation, wind, relative humidity, air temperature, and the surface area of the exposed water.
On average, an uncovered reservoir can lose between 1,600 – 3,700 liters of water per m² per year.
Real example: invisible losses that cost millions
- A 1-hectare (10,000 m²) reservoir can lose up to 37,000 liters per day.
- Mining reservoirs are often even larger, so evaporation losses reach tens of millions of liters per year.
Reducing evaporation under these conditions is not just an environmental measure: it's an economic and operational necessity.
Case 1 – Agriculture:
A blueberry grower in Perú, with a 2-hectare reservoir, estimated that "there was just enough water for the season." After calculating evaporation, he discovered that he was losing more than 42 million liters each year due to sun and wind exposure alone.
Case 2 – Mining:
In Chile, for example, a 5-hectare reservoir can lose 185 million liters per year, compromising processes and forcing the consumption of more fresh water.
How to calculate evaporation in your reservoir for free
At Covex®, we have developed our own algorithm that accurately estimates how much water evaporates in each case. We make it available to farmers and companies free of charge because we believe that information is the first step toward water efficiency.
Steps to request your free Covex evaporation report
- Contact us.
- Indicate the surface area (in m² or hectares) and the location of the pond(s).
- Once the report is ready, we will schedule a video call to present it to you.
With this report, you'll have a clear estimate of how much water you lose and how much you could recover if you decide to cover your reservoir.
Solutions to reduce evaporation in reservoirs
There are several alternatives, but not all are equally effective.These are the most common:
- Shade nets / geomembranes: partially reduce solar exposure, but do not prevent wind-driven evaporation.
- Floating covers: modular HDPE covers that adapt to any pond size and reduce evaporation by more than 90%.
In addition, floating covers help:
- Avoid algae proliferation in irrigation reservoirs.
- Improve water quality by reducing dust and organic matter.
- Lower water temperature, optimizing agricultural and mining processes.
Environmental benefit: circular water economy
Every liter of water recovered is one less liter extracted from rivers, groundwater, or desalination plants. This reduces the water footprint of agriculture and mining and positions companies as leaders in sustainability.
- Reducing evaporation in irrigation reservoirs means more water for crops, less stress during droughts, and lower irrigation costs.
- Reducing evaporation in mining reservoirs ensures stable processes, lower environmental impact, and compliance with ESG commitments.
Conclusion: protecting every drop matters
Reducing evaporation in reservoirs is not only about saving money—it is about securing water for the future.
Request your free evaporation report and discover how many millions of liters you could recover with Covex®.