Decoding Pool Water Evaporation: Does it Happen Under Winter Covers?

Ever wondered if your pool’s water can evaporate under a winter cover? It’s a common question that puzzles many pool owners as they prepare for the chillier months. This article aims to delve into the science behind pool water evaporation in winter, providing you with insights that might just surprise you.

Key Takeaways

  • Pool water does evaporate under a winter cover, albeit at a slower rate due to the shielding effect of the cover.
  • A winter cover, while reducing the rate of evaporation, doesn’t entirely stop it. Tiny pockets of air between the cover and the pool water allow for water molecules to escape.
  • Factors like temperature, wind speed, and humidity need to be considered when estimating the evaporation rate. For instance, a heated pool will have a greater rate of evaporation even in winter.
  • Apart from curbing water losses, winter covers provide additional benefits such as preventing debris from falling into the pool, saving on water bills, conserving pool chemicals, and blocking the formation of algae.
  • Proactive measures to minimize water evaporation in winter include using a heavy-duty pool cover, reducing the pool’s temperature, maintaining optimal water levels, installing fences or windbreaks, and using water evaporation reducers such as a liquid solar cover.
  • Assessing the cost-efficiency of these preventive measures is important. Investment costs such as the price of the pool cover, maintenance expenses, wind protection costs, and the cost of water evaporation reducers need to be weighed against benefits like water and energy savings, and the preservation of pool quality.

Understanding Pool Water Evaporation

When it comes to water evaporation from your swimming pool, a rudimentary grasp of the physics involved can help you appreciate the process. Despite the common belief, scientific facts illustrate that pool water does evaporate, even when protected by winter covers.

The Universality of Evaporation

You might regard evaporation as a phenomenon largely limited to warm environmental conditions. However, evaporation is a continuous physical process irrespective of the temperature. It occurs when molecules at the water’s surface convert to a gaseous state – the warmer these molecules, the faster they’ll evaporate. Yet, it’s crucial to know, even at colder temperatures, albeit slower, evaporation doesn’t entirely cease.

For instance, your hot cup of coffee displays steaming evidence of rapid evaporation due to the high temperature while a cool glass of water is also experiencing evaporation, even if you can’t visually discern it.

Effect of Winter Covers on Evaporation

Hypothetically, you’d presume winter covers would prevent evaporation, acting as a physical barrier. Recognize that while covers do reduce evaporation rates by up to 95%, according to the US Department of Energy, they’re not fool-proof.

Given a high-quality, correctly installed cover can effectively limit evaporation, trace amounts of water still escape into the atmosphere. Essentially, winter covers primarily slow down but can’t stamp out the process of evaporation.

Winters and Pool Water Evaporation

Worth noting, the misconception that cold winters bring evaporation to a halt is a common one. It’s the temperature difference between the water surface and the surrounding air—generally cooler at night—that brings about a higher rate of evaporation. So, inevitably, your pool water continues to evaporate, albeit at a reduced pace, even under the winter cover during the cold season.

The Winter Cover and its Importance

A winter cover plays a crucial part in combating pool water evaporation during the colder months. Irrefutably, it forms a protective shield, slowing down the evaporation process. But it’s a shield, not an impenetrable barrier; evaporation continues, albeit at a reduced pace.

Let’s explore the primary benefits of a winter cover for your pool. These benefits don’t merely relate to reduced evaporation, but extend to various other parameters.

  • Protection against Debris: Stop worrying about leaves, twigs, and other outdoor debris. The cover serves as a reliable barrier, ensuring your pool remains clean during the off-season. A clean pool means less required maintenance when pool usage times arrive.
  • Saving on Water Bills: As alluded to earlier, the cover causes a significant drop-off in the rate of water evaporation. This decreased rate means less water refills and consequentially, less expenditure on your water bills.
  • Conservation of Pool Chemicals: Regular evaporation can cause an imbalance of your pool’s chemicals. A winter cover mitigates this issue, thereby reducing the frequency and intensity of chemical treatments required when it’s time to use the pool again.
  • Prevention of Algae Growth: Many types of algae thrive in sunshine. A winter cover, serving as an opaque barrier, blocks sunlight, impeding unnecessary algae growth.

Even with these advantages, it’s crucial to remember that a cover isn’t a full-proof solution for evaporation. Particularly during warmer winter days, or in cases of a heated pool, the laws of physics persist; water evaporation continues. Nonetheless, a winter cover provides valuable benefits and plays a significant role in mitigating the physical processes at play.

Covering your pool during winter isn’t just a good idea; it’s a best practice. So this winter, do yourself a favor, install that cover and reduce the effects of pool water evaporation. You’ll be thankful when the sweltering heat of summer revisits and your pool is fresh, clean, and ready to dive into.

Does Pool Water Evaporate Under Winter Cover?

Yes, pool water does evaporate, even under a winter cover. However, covering your pool can greatly lessen the rate of evaporation. An uncovered pool loses water at an accelerated pace due to factors like wind and sun exposure. Using a pool cover certainly mitigates these effects.

When determining the evaporation rate, different factors come into play. Temperature, humidity, and wind speed – these are chief among them. For instance, if your pool is heated, temperature differences can enhance evaporation. Warmer winter days also lead to increased evaporation under the winter cover.

It’s important to remember that a winter cover serves to significantly curb water loss, but it’s impossible to completely halt the evaporation. This is because a winter cover cannot seal off the pool water perfectly from its ambient environment. Tiny pockets of air that exist between the cover and the water surface serve as conduits for water molecules to escape.

Despite this, the advantages of using a winter cover far overshadow its mild inability to stop evaporation fully. For one, it impedes debris from falling into your pool, saving you considerable cleaning time. Additionally, a covered pool saves you money on your water bill by reducing the quantity of water lost to evaporation.

Notably, a cover conserves the pool chemicals that also can evaporate along with water. By preserving these chemicals, you’re blocking the formation of algae, ensuring a cleaner pool when summer arrives.

In a nutshell, pool water does evaporate under a winter cover, though at a much-reduced speed. It’s recommended that you cover your pool during winter, not solely to protect it from debris or to reduce water evaporation, but to maintain the stability of your pool’s chemical balance and prevent algae growth.

Tips to Reduce Pool Water Evaporation During Winter

Pooling your resources to minimize water evaporation in winter can be beneficial. The fact that pool water evaporates less under the winter cover doesn’t eliminate the need for preventive measures. Various strategies can curb this unnecessary loss, ensuring an efficient upkeep of your pool during colder months.

A heavy-duty pool cover tops the list. Look for one with double stitching, UV protection, and mesh screening on top. These additional features not only increase the durability and weather resistance of the cover, they also contribute to reducing evaporation.

Next, maintain your swimming pool at a lower temperature. Hot water evaporates more quickly than cooler water. So, even if your pool’s heating system offers comfort during winter swims, turning down the heat can save your water levels from dropping noticeably.

Your pool’s water level is another essential aspect to monitor. Less surface area equates to reduced evaporation. So, maintain your water levels to be about 3-5 inches below the pool edge.

Proactive protection of your pool from wind exposure plays a crucial role, too. Fences or windbreaks, provide a deterrent to the speed and volume of wind hitting your pool surface, assisting in the prevention of rapid and excessive evaporation.

Lastly, the use of a pool water evaporation reducer, like a liquid solar cover, can be an added layer of defense. These products form a thin, invisible layer on your pool’s surface, dramatically lowering the rate at which water molecules escape.

Adopting these tips can assist you in keeping your pool at its optimal level during the winter months. Even though a winter cover already reduces the rate of evaporation, these additional strategies offer further protection against water loss and pool maintenance inefficiencies. Be sure to utilize them for the most effective pool upkeep this winter.

Assessing the Costs and Benefits

Implementing preventive measures for pool evaporation requires both time and monetary investment. The balance between what you invest and the benefits you receive determines whether these strategies represent sound tactics.

Investment Costs

  1. Covering Costs: Purchase of a high-quality winter pool cover accounts for the most significant bulk of the costs. Market prices vary, but generally, superior covers, which promise better durability and performance, can range between $75-$350.
  2. Maintenance Expenses: Maintaining optimal water levels and temperature forms another cost aspect. Heating your pool to a lower, yet comfortable temperature can increase electricity consumption, while replenishing water levels to maximize evaporation control may impact your water bill.
  3. Wind Protection Costs: Commit to windbreaks or fences to guard against wind exposure. Depending on materials, the price for enclosures fluctuates between $15-$100 per linear foot.
  4. Water Evaporation Reducers: This specialized product, designed to form an invisible barrier on the water surface to restrict evaporation, costs approximately $15-$40 per quart.

Expected Benefits

Despite the inevitable expenses, the cost-efficiency of earlier discussed strategies emerges from the manifold benefits.

  1. Water Conservation: High-quality covers, proper water levels, and evaporation reducers significantly reduce water loss. Lower consumption translates to less frequent refills, thus conserving a vital resource and lowering cost in the long run.
  2. Energy Savings: A well-insulated pool loses heat slower, which, in turn, reduces heating costs. Consequently, proper temperature management boosts energy efficiency.
  3. Preserved Pool Quality: Prolong durability of your pool liner and equipment, as a cover guards against debris while minimizing chemical degradation due to wind exposure. These safeguards collectively extend the lifespan of your pool accessories, thereby postponing replacement expenses.

Carefully weigh these tangible benefits against the upfront costs. By doing so, you’ll be more informed whether these preventive measures serve as worthy investments in preserving your pool’s quality throughout the winter season.


So, does pool water evaporate under a winter cover? Yes, it does, but at a slower rate. Your pool’s winter cover plays a vital role in reducing water evaporation, conserving water, saving energy, and maintaining your pool’s quality. It’s a worthy investment, even with the initial costs. But remember, it’s not just about buying a high-quality cover. You’ve also got to keep an eye on the water levels and temperature, and protect your pool from wind exposure. Implementing these preventive measures can seem daunting, but when you weigh it against the long-term benefits, it’s clear they’re worth it. You’re not just saving water and energy, but you’re also preserving your pool for many winters to come. So, make the investment, take the necessary steps, and enjoy the benefits.

What factors contribute to pool water evaporation in winter?

Winter pool water evaporation is mainly affected by factors like temperature variations, wind exposure, and pool water levels. A drop in air temperature increases evaporation, as does exposure to wind. Maintaining optimal water levels can help reduce this natural process.

What are the benefits of using winter pool covers?

Winter pool covers are a smart investment to minimize pool water evaporation. They aid in conserving water, saving energy, and preserving the quality of your pool.

What costs might be involved in preventive measures against water evaporation?

To effectively prevent water evaporation in your pool, there would be upfront costs for buying high-quality winter pool covers, regulating water levels, protecting against wind, and using evaporation reducers.

Why should I consider these preventive measures despite the costs?

Notwithstanding the costs, implementing preventive measures ultimately provides long-term benefits. These include water conservation, energy savings, and a maintained quality of the pool, which might outweigh the initial investment.

Is it advisable to evaluate these benefits against the upfront costs?

Indeed, it is essential to weigh these benefits against the costs. Carefully considering the long-term benefits against the initial costs can help determine if these preventive measures are valuable for maintaining your pool’s quality over the winter season.