Nothing can ruin a relaxing day of lounging poolside or kicking back on a pool float like the realization that your pool is rapidly losing water. All pools lose a small amount of water each day to evaporation and splashing. However, an excessive drop in a pool’s water level is typically due to either a more significant evaporation issue or a leak. Both causes require attention, as low water levels can lead to more serious problems, such as poor pool circulation.
If there’s not enough water in a pool, the pump and filtration systems’ efficiency becomes compromised. As a result, the pool’s water can become cloudy, algae growth can increase, and the pool equipment may even become damaged. Consistent water loss also means frequent pool refilling, which increases water usage and utility bills and requires more chemicals to maintain water quality and hygiene. If water loss is happening because of a leak, the rapid and excessive water loss can threaten the pool’s structure and surrounding materials. That’s why it’s so important for homeowners to be able to spot the difference between evaporation and water leaks in their pools.
How Much Pool Water Loss Is Normal?
According to Alicia Toedter, senior manager of content strategy at the national pool and spa care brand Leslie’s, “The average pool loses about ¼ inch of water per day unless a solar pool cover is used to cut down on evaporative water losses.” Evaporation is the primary cause of this water loss, and climate and environmental factors can exacerbate it. “Pools in especially hot, dry, or windy climates can lose even more, as these factors increase the evaporation rate,” says Toedter. “Other things like splash-out and backwashing the filter can also remove water from the pool.”
These causes of water loss are normal, so it’s a good habit to check water levels regularly. Getting familiar with your pool’s typical water loss—say, a slight dip after a windy day—helps you spot when something’s off. As a rule, it’s generally only necessary to add 1 to 2 inches of water to the pool each week. “If you’re noticing the water level dropping more than a couple of inches per week for no apparent reason, odds are you’re dealing with a pool leak,” Toedter adds.
Pro Tip: Keep a simple log of when you add water and how much. It doesn’t have to be fancy—just jot it down in a notebook or on your phone. This can help you notice patterns over time, like if water loss spikes during certain weather or after heavy pool use, making it easier to catch a potential issue early.
How to Identify Pool Water Evaporation vs. Leaks
An excessive drop in pool water levels (beyond expected splash and evaporation loss) often points to a leaky pool. To maintain pool health, homeowners need to know the difference between environmental conditions causing evaporation and structural damage or a plumbing issue causing leaks.
Pool Water Evaporates More Quickly in Warmer Months
Pool evaporation rates increase in the warmer months of spring and summer when temperatures are consistently warm. Both higher temperatures and intense sunlight contribute to faster evaporation of water from a pool’s surface. If the water level in a pool drops more noticeably as the weather warms, it is likely that evaporation is the primary cause of water loss during these seasons. Additional environmental factors like lower humidity and increased wind can further accelerate this evaporation process.
Rafi Friedman, president of Florida-based pool building company Coastal Luxury Outdoors, advises that pool owners pay regular attention to their pool and the weather forecast. “Humidity levels play a big role in how quickly water will evaporate,” he says. “If things have been dry, more evaporation should be expected. If you notice a larger-than-usual dip in water level even when it’s humid, or especially if you’ve kept your pool covered, you may have a leak on your hands.”
If homeowners find themselves adding water to their pool at higher volumes or more frequently than average water loss rates require, this could be a sign of a leak. The best way to combat evaporation issues typically involves installing a solar cover for the pool. Additionally, covering the pool area with a pool enclosure can also help. A pool screen enclosure costs between $5,708 and $16,608 on average.
Did You Know? Solar covers don’t just reduce evaporation—they can also warm your pool by up to 10–15°F, extending your swimming season. They’re not perfect, though; they can be a bit cumbersome to put on and take off, so consider a reel system for easier handling if you’re going this route.
| Season | Monthly Water Loss in Gallons | Monthly Water Loss in Inches |
|---|---|---|
| Winter | 712 | 2.8 |
| Spring | 1,950 | 7.8 |
| Summer | 2,450 | 10.1 |
| Fall | 1,400 | 5.7 |
Signs of a Pool Leak
Excessive Moisture Around the Pool
When a pool leaks, the water typically seeps into the ground surrounding the pool. Depending on the pool’s location, this could result in sinking decks or patios, muddy or soggy spots in the grass, or even cracks appearing on the surface of the concrete surrounding the pool. “If you notice unusually soggy spots in your lawn, or water trickling out of your lawn into a nearby gutter or storm drain, it may be coming from your pool,” Friedman says. Over time, water seepage from a leaking pool can cause soil erosion or damage the pool’s structural integrity and the surrounding area. It’s important to address any signs of pool leaks right away to avoid costly repairs.
Increased Chemical Usage
Treating a pool with chemicals is an essential part of both in-ground and above-ground pool maintenance. Homeowners may notice they need to increase the amount of pool stabilizers and other chemicals required to maintain the water quality if they have a swimming pool leak. The fresh water added from the hose to compensate for the leaked water will dilute the existing chemical balance in the pool, making it less effective. More chlorine, algaecides, and pH balancers are needed to keep the pool water clear and safe for swimming. “A sudden increase in chemical usage or difficulty maintaining proper water chemistry can…be indicators of a leak,” said Toedter. “This is especially true if you’re using an auto-fill valve that adds fresh water automatically.” Early leak detection in swimming pools can lessen pool maintenance costs in the form of water and chemicals.
Practical Note: If you’re constantly adding chemicals and still struggling to keep the water clear, double-check your pool’s pH and chlorine levels with a test kit. Sometimes, it’s not just a leak—unbalanced water can make it seem like you need more chemicals when the real issue is dilution from a sneaky leak.
Soaring Water Bills with Auto-Fill Systems
Automatic filling pools are designed to maintain water levels seamlessly; however, a leak will cause the system to go into overdrive. More water will be needed than usual, which will result in significantly higher water costs over time. Since the pool is being refilled constantly, it may not be obvious that the pool is losing water until the utility bill comes. If a homeowner notices the system is running more frequently than normal—especially without increased usage or evaporation conditions—it’s likely a sign that water is escaping through an unseen leak.
Visible Cracks in the Pool
It’s worth doing a visual inspection of the pool for any cracks. If there is water seeping through these fractures, it can undermine the integrity of the surrounding area and the base of the pool. “Once you’ve found the crack, drain your pool below that point, then address the problem,” says Friedman. “Small cracks can be dealt with using at-home patch kits or sealer, while bigger ones should be left to professionals.” Taking a proactive approach to pool leak detection will prevent escalated repair costs and a possible pool closure to fix a significant leak.
Testing for a Leak: The Bucket Test
Jimmie Meece, brand president of national pool service franchise America’s Swimming Pool Company, recommends performing the “bucket test” to rule out normal evaporation and potentially detect a leak in a pool. To do this, fill a bucket with pool water and place it on the first or second step inside the pool so the water level inside the bucket matches the water level inside the pool. Mark both water levels inside and outside the bucket. Leave the bucket in this spot for 24 hours without adding any additional water to the pool during this time. Then, compare the water levels after the test window. “If the pool water, which is the outside mark on the bucket, goes down more than the inside water level, there is probably a leak,” says Meece. “Document the water level drop in inches.”
Meece also notes that if it rains during the 24-hour period, homeowners will need to repeat the bucket test to confirm the leak. As a follow-up test for a suspected leak, Meece also recommends the “24 hours on” test to differentiate between a leak in the plumbing system and one in the shell of the pool. To do this, fill the pool so the water level is neither above nor below the skimmer, then mark the level. Turn off any auto-fill valves and run the pool pump for a full 24 hours before checking the water level again. If the water level has dropped below the mark, it could indicate a plumbing leak.
Meece adds that it’s important to make sure that no water is leaking from the “backwash line,” (the pipe carrying waste water away from the pool) when the pump is running. “If you’re losing water from the backwash line, you’ll need to repair or replace the multiport valve on your filter,” says Meece.
Quick Tip: When doing the bucket test, use a heavy bucket and weigh it down if needed—light plastic ones can tip or float, messing up your results. And don’t skip marking the levels clearly; a smudged mark can make the whole test useless.
Finding the Leak: The Dye Test
Once it’s clear that the problem is actually a leak, it’s time to learn how to find a leak in a pool. “Certain clues may help you pinpoint exactly where the leak is coming from, if not readily apparent,” Toedter says. “For example, does the water level drop faster when the pump is on? If you turn the pump off and let the water level drop, does it stop at a certain point in the pool?” The most common leak areas include the skimmer, pool lights, plumbing returns, cracks or tears in pool surfaces, and plumbing joints and unions that connect your equipment to the pool.
In the absence of these clues, a dye test can help determine the leak location. This is when a small amount of dye—food coloring or a specially formulated dye—is introduced to the pool while the water is still and the pumps are not running. Apply the dye near cracks, fittings, and around the edges of the pool liner—anywhere leaks are most likely to occur. The dye will flow toward the leak to visually show the homeowner where the pool is losing water and make the process of finding a pool leak much easier. Once identified, some cracks can be temporarily repaired with a pool patch, but it’s a good idea to have a professional inspect the pool and perform more permanent repairs.
Heads-Up: If you’re using food coloring for the dye test, go easy—a little goes a long way. Too much can tint your water, and while it’s not harmful, it might look weird for a day or two. Stick to a drop or two near suspect areas.
Who to Call for Pool Leak Repair
For advanced leak detection, Toedter says that a pool service professional may be needed to pinpoint the exact location. “This is especially true for underground plumbing leaks that may have resulted from freeze damage or shifting soil,” she adds. A pool repair company has the expertise and tools for detecting pool leaks that might not be readily accessible to homeowners. Some of the best pool cleaning services and best pool installation companies also offer repairs, so homeowners who already use these services may want to inquire about this if they suspect a leak.
First, the pool technician will perform a pool inspection to assess the problem. A pool inspection costs about $125 to $250. Following a thorough inspection, a pool service specialist may recommend solutions ranging from pool resurfacing or liner replacement (homeowners can expect pool resurfacing costs of around $6,500, and pool liner replacement costs $2,393 on average). The cost of pool leak repairs seems minimal when the root cause of water loss is identified and effectively addressed. Additionally, pool professionals often provide valuable maintenance tips and strategies to prevent future issues and keep the pool in optimal condition for safe and enjoyable use.
Extra Advice: When hiring a pro, ask for a detailed breakdown of the inspection andrepair process. Some companies might rush through or push unnecessary fixes, so it helps to know exactly what they’re checking—like pressure testing pipes or inspecting the skimmer seals. A good technician will walk you through their findings without jargon overload.
Nothing can ruin a relaxing day of lounging poolside or kicking back on a pool float like the realization that your pool is rapidly losing water. All pools lose a small amount of water each day to evaporation and splashing. However, an excessive drop in a pool’s water level is typically due to either a more significant evaporation issue or a leak. Both causes require attention, as low water levels can lead to more serious problems, such as poor pool circulation. By regularly monitoring your pool, using tests like the bucket or dye test, and calling in professionals when needed, you can keep your pool in top shape and avoid costly repairs down the line.