The shimmering expanse of a backyard pool is a source of joy, relaxation, and escape. But for many pool owners, that serene view is often clouded by a recurring question: “Why is my pool water disappearing?” A certain amount of water loss is inevitable, but when the level drops noticeably, it can be a sign of a larger, more costly problem. This article will explore the common reasons behind a disappearing pool, from the natural and harmless to the hidden and troublesome. We’ll also provide simple, at-home tests you can perform to pinpoint the issue before calling a professional.
The Unavoidable Culprit: Evaporation
The most frequent and often largest source of water loss is evaporation. It’s a natural process where water molecules, energized by heat, convert into vapor and rise into the air. The rate of evaporation can be significant and is influenced by several environmental factors:
- Temperature: The hotter the water and the air, the faster the water evaporates. A sun-drenched pool on a scorching day will lose more water than one on a cool, cloudy day.
- Humidity: Dry air acts like a sponge, readily absorbing water vapor. In low-humidity environments, evaporation rates are much higher.
- Wind: A strong breeze sweeping across the pool’s surface can drastically accelerate water loss. The wind carries away the layer of humid air directly above the water, allowing more water to evaporate.
- Surface Area: Quite simply, a larger pool has more surface area exposed to the elements, leading to greater evaporation.
A good rule of thumb is that a pool can lose a quarter to half an inch of water per day to evaporation alone. While this may seem like a lot, it is a normal and expected part of pool ownership. Using a pool cover can dramatically reduce this kind of water loss.
The Fun, Yet Costly, Pool Consequence: Splash-Out
Splash-out is the most obvious cause of water loss. Every cannonball, every game of Marco Polo, and every energetic swim sends water flying over the pool’s edge. While it’s the most joyful way to lose water, it can add up quickly.
- High-Energy Activities: Kids and adults alike love to play in the pool, and these activities inevitably lead to water being displaced and lost.
- Pool Parties: A gathering with many people will result in significant water loss in a short period.
- Over-filling: Filling the pool too high leaves a smaller margin for activity, and even minimal movement can cause water to slosh out.
While it’s difficult to prevent splash-out entirely, being mindful of the water level and encouraging less vigorous play can help.
The Hidden Threat: Pool Leaks and How to Find Them
If you’ve accounted for evaporation and splash-out and your pool water is still dropping at an alarming rate, a leak is the most likely culprit. Leaks can be tricky to find because they can occur in the pool’s structure, plumbing, or equipment. Before calling a professional, you can perform these simple tests to pinpoint the issue.
The Bucket Test: Your DIY Evaporation vs. Leak Check
This test is the gold standard for determining if you have a leak.
- Place a bucket on a pool step.
- Fill the bucket with pool water, leaving it about an inch from the rim.
- Mark the inside of the bucket at the water level.
- Mark the outside of the bucket at the pool’s water level.
- Turn off the pool pump and all automatic fillers.
- Wait 24 hours.
- Compare the water levels. If the water level in the pool has dropped more than the water level in the bucket, you likely have a leak. If both levels drop by the same amount, the water loss is likely due to evaporation.
- Bucket Test For Pool Leaks Detection
The Dye Test: Pinpointing Structural Leaks
Once you’ve confirmed a leak, this test can help you find its location in the pool structure.
- Turn off the pool pump. The water needs to be completely still.
- Use a small bottle of leak detection dye (available at most pool supply stores). A syringe is often included for straightforward application.
- Go to the areas most likely to have leaks: lights, skimmers, returns, and any visible cracks in the pool’s shell or liner.
- Squeeze a small amount of dye near the suspected area. The dye is heavier than water and will be drawn into the crack or opening if a leak exists. If you see the dye being sucked into an area, you’ve found your leak.
- Dye Testing
The System Test: Checking the Plumbing
To determine if the leak is in your plumbing, you can perform a variation of the bucket test.
- Perform the Bucket Test with the pump running for 24 hours.
- Repeat the test with the pump turned off for 24 hours.
- Compare the results. If the water loss is significantly greater when the pump is running, the leak is likely in the pressurized return side of the plumbing. If the water loss is consistent in both tests, the leak is likely in the structure or the skimmer line.
Other Contributing Factors
Beyond the primary culprits, a few other factors can contribute to water loss:
- Backwashing: For pools with a sand or DE filter, the process of backwashing to clean the filter can use a significant amount of water.
- Automatic Fillers: A malfunctioning automatic filler can lead to constant water loss as it tries to overcompensate for a non-existent drop in the water level.
- Pets and Wildlife: While not a major factor, dogs swimming in the pool or other animals drinking from it can contribute to a small amount of water loss over time.
Conclusion
The disappearing act of pool water is a common and often frustrating problem. While some water loss is a normal part of pool ownership, an unusually low water level is a sign that something is wrong. By understanding the difference between natural causes like evaporation and human-made ones like splash-out and potential problems like leaks, you can take proactive steps to maintain your pool’s water level. Performing a simple bucket test and other DIY checks can help you catch problems early and keep your backyard oasis ready for a swim.