Dam Evaporation in Australia: What It Is, Why It Matters, and How to Stop It

Every year, Australian farms, mines, and water infrastructure projects lose an estimated 750 billion litres of water to evaporation — water that has been captured, stored, and paid for, simply vanishing into the air.

That’s not a minor inefficiency. For many operations, it’s one of the single largest and most preventable water losses on site. Understanding dam evaporation Australia-wide is the first step toward doing something about it.

What Is Evaporation?

Evaporation is the process by which liquid water absorbs heat energy and transforms into water vapour, rising into the atmosphere. It’s a fundamental part of the global water cycle — helping drive rainfall, regulate temperatures, and sustain ecosystems.

But when evaporation occurs from an open dam, storage pond, or irrigation reservoir, it doesn’t come back. That water is gone.

For a deeper dive into the science, read our full guide: What is Evaporation?

Why Dam Evaporation in Australia Is a Serious Problem

Australia is one of the driest inhabited continents on Earth — and its climate makes evaporation a particularly acute challenge. High summer temperatures, persistent dry winds, low humidity, and large open water surfaces combine to create near-perfect conditions for rapid moisture loss.

The scale is significant:

• Australia has approximately 50,000 farm dams and open water storages across the country
• Collectively, these lose an estimated 750 billion litres per year to evaporation
• The average dam loses around 15 million litres per year — enough to irrigate several hectares of crops or supply a small rural property

For farmers managing tight seasonal water budgets, that kind of loss isn’t just inconvenient. It’s a direct threat to productivity, livestock welfare, and long-term viability. For mining operators and infrastructure managers, it translates into increased refilling costs, higher pumping energy consumption, and risks to operational continuity.

Managing dam evaporation isn’t just good environmental practice — it’s sound financial management.

Key Factors That Influence Evaporation Rates

Not all dams lose water at the same rate. Several environmental and physical variables determine how fast evaporation occurs:

• Temperature: Higher ambient temperatures give water molecules more energy to escape the surface. On hot Australian summer days, evaporation rates can be extreme.
• Wind speed: Moving air carries vapour away from the surface, constantly exposing fresh water to the atmosphere and accelerating loss.
• Relative humidity: Dry air has a greater capacity to absorb moisture. In arid and semi-arid regions of Australia, low humidity intensifies evaporation year-round.
• Surface area: A larger exposed water surface means more evaporation. Shallow, wide dams lose proportionally more water than deeper, narrower ones.
• Solar radiation: Direct sunlight heats the water surface and drives the phase change from liquid to vapour.

Understanding which of these factors is dominant at your site helps determine the most effective evaporation control strategy.

Evaporation Control for Dams: What Are the Options?

Once you understand the problem, the next question is: what can actually be done about it?

At EvapCo, we’ve developed a range of practical, proven solutions tailored to Australian conditions:

Dam Covers and Floating Covers

Purpose-engineered dam covers physically block the water surface from solar radiation and wind exposure — the two biggest drivers of evaporation. Floating covers can be manufactured to suit dams of almost any shape and size, from small farm dams to large industrial storages. They also reduce algae growth and contamination risk as an added benefit.

Shade Balls and Surface Modifiers

Floating shade balls — buoyant spheres that sit on the water surface — provide a scalable, low-maintenance option for reducing evaporation on open storages. They’re particularly suited to larger or irregularly-shaped bodies of water where a rigid cover isn’t practical.

Monitoring and Management Systems

Data-driven evaporation management starts with understanding your actual losses. EvapCo’s monitoring solutions provide real-time visibility into storage levels, evaporation rates, and conditions — giving operators the information they need to make better water management decisions.

Site-Specific Consulting

Every water storage is different. Our team works with Australian farms, mines, and infrastructure operators to assess site-specific conditions and design evaporation control strategies that deliver measurable results.

To explore these methods in detail, see our post on 5 methods of mitigating evaporation loss in dams.

The Real Cost of Doing Nothing

It’s tempting to treat evaporation as just a natural occurrence — something that can’t be avoided. But the numbers tell a different story.

If your dam loses 15 million litres per year to evaporation, and you’re refilling it from a metered bore, irrigation scheme, or water delivery service, that loss has a direct dollar cost. Factor in the energy required for pumping, the wear on infrastructure, and the opportunity cost of water that could be used productively — and the financial case for evaporation control becomes very clear.

In regions where water allocations are capped or declining, every litre recovered from evaporation loss is a litre that stays in your system.

Frequently Asked Questions About Dam Evaporation in Australia

Q: How much water does an average Australian farm dam lose to evaporation each year?

The average open farm dam in Australia loses approximately 15 million litres per year to evaporation. This figure varies depending on location, dam size, and local climate — dams in hotter, drier regions (such as inland Queensland, Western Australia, or outback NSW) will typically lose more. Across Australia’s estimated 50,000 farm dams, annual losses total around 750 billion litres.

Q: What is the most effective way to reduce dam evaporation?

The most effective method depends on your site’s specific conditions, but physical barriers — such as floating dam covers or shade balls — consistently deliver the highest evaporation reduction rates by directly blocking solar radiation and wind exposure. In many cases, a well-installed dam cover can reduce evaporation losses by 70–90%. Monitoring systems help quantify the problem and track the impact of any controls put in place.

Q: Does reducing dam evaporation really make a financial difference?

Yes — for most operations, it makes a significant difference. When you account for the cost of replacing lost water (whether from pumping, allocation purchases, or delivery), plus the energy costs involved, reducing evaporation often delivers a return on investment within a few seasons. For sites in water-stressed regions or with large storage volumes, the payback can be even faster.

Take Control of Your Water Loss

Evaporation is a natural process — but the losses it causes don’t have to be accepted. With the right solutions in place, Australian farms, mining operations, and infrastructure projects can recover millions of litres of water per year that would otherwise disappear into the atmosphere.

At EvapCo, our mission is simple: help Australian industries use water more efficiently. From the first site assessment through to installation and ongoing monitoring, we provide end-to-end evaporation management solutions designed for real Australian conditions.

Ready to find out how much water your dam is losing — and what it’s costing you?

Contact our team today to start building your water-smart future.