Why Pools Lose Water in Cold Weather: A San Antonio Perspective

As cooler months roll in, it’s not uncommon for pool owners in San Antonio to notice a slight drop in their pool water levels. Many people reach out with concerns, wondering if there’s an issue with their pool. While water loss can occasionally result from leaks in pipes or equipment, most often, it’s due to natural factors specific to the season. Here are the primary reasons your pool might be losing water in colder weather — plus a simple test you can do at home to find out if there’s an actual leak.

1. Evaporation

It may surprise you, but pool evaporation doesn’t stop in the winter! In fact, colder months can still produce significant water loss due to evaporation, especially when the air is dry and temperatures swing between warm days and chilly nights. San Antonio’s winter weather often brings just that — low humidity with cooler air. The greater the temperature difference between the pool water and the surrounding air, the faster evaporation occurs.

Even though you’re not swimming, it’s common to lose up to 1/4 to 1/2 inch of water per day to evaporation, depending on factors like wind and temperature.

2. Wind and Dry Air

Cold winter air is typically much drier than the warmer, more humid air we experience during other parts of the year. When dry, cool air blows across the surface of your pool, it accelerates evaporation. This effect is compounded by San Antonio’s weather patterns, where frequent cold fronts bring in gusts of dry air that can easily whisk water molecules away from the pool.

If your pool is uncovered, it’s even more vulnerable to the effects of wind and dry air. A well-fitted cover can help reduce exposure to the elements and slow the evaporation process.

3. Lower Humidity Levels

San Antonio is known for its humid summers, but during the winter, we get much drier air. Since cold air can’t hold as much moisture, there’s a larger difference in moisture content between the pool water and the surrounding air, which encourages water to escape as vapor. The dry winter air essentially “pulls” moisture from the pool, causing water levels to drop over time.

Is It a Leak or Just Evaporation?

If you’re concerned about water loss, one of the easiest ways to check if you have a leak is to do a bucket test. Here’s how:

  1. Fill a bucket with water and place it on the first or second step of your pool, so it’s partially submerged.
  2. Mark the water levels on both the inside and outside of the bucket.
  3. Wait 24 hours, then check to see if the water levels in the bucket and the pool have dropped equally.

If both levels go down by the same amount, it’s likely due to evaporation. If the pool level goes down more, you may have a leak. Don’t hesitate to contact us for professional help if you’re unsure about the results or need assistance with repairs.

Final Thoughts

While water loss during winter is often due to natural factors, being vigilant with tests like the bucket test can help identify potential issues before they become bigger problems. In most cases, evaporation is the main cause, but our team at Everblue Pools is always here to help if you need a closer inspection or have questions. Stay warm and enjoy your pool this winter!