Pool Water Evaporation Chart: Is Your Marietta Pool Losing Too Much?

You keep checking the waterline, and it keeps dropping, and you cannot tell if that is normal or something worse. Georgia summers push pool water evaporation into overdrive, and the humid air makes it even more confusing. One week your pool looks fine; the next, you are topping it off every other day and wondering if you have a leak.

That uncertainty is common across Marietta, and it usually comes down to a missing reference point. A pool water evaporation chart gives you a real number to compare against your own water loss, instead of guessing. Once you know what counts as normal for your pool size and Georgia's climate, the mystery mostly disappears.

In this guide, you'll discover how to read a pool water evaporation chart built for Georgia conditions, how to run a simple bucket test at home, and what water-loss numbers should prompt a professional look. 

Read the Georgia Water-Loss Benchmarks First

Georgia's humid summers actually slow evaporation compared to drier states, but the numbers still add up fast. Knowing the baseline is the first step to reading any pool water evaporation chart correctly.

Humid subtropical climates like Georgia typically see less daily water loss than dry states such as Arizona or Nevada. Moist air holds less capacity for additional moisture, so evaporation happens more slowly even on hot days. That does not mean your pool loses nothing; it just means the pace looks different from what national charts often show.

Typical Daily, Weekly, and Monthly Loss in Marietta

Marietta pools in summer typically lose between one-eighth and one-quarter inch of water per day. Over a full week, that adds up to roughly 1 to 1.5 inches under normal conditions.

Monthly totals for an uncovered residential pool usually range from 600 to 1,200 gallons, depending on pool size and weather. A hot, dry stretch with wind can push that number higher even in Georgia's humidity.

• Daily evaporation (Marietta summer): 1/8 to 1/4 inch
• Weekly evaporation: 1 to 1.5 inches
• Monthly evaporation (uncovered pool): roughly 600 to 1,200 gallons
• Annual evaporation estimate: 7,000 to 12,000 gallons for most residential pools

When a Dropping Water Line Is More Than Normal Evaporation

A water line that drops more than three-eighths of an inch per day in Marietta is worth watching closely. That pace outruns what humidity and normal Georgia heat should cause on their own.

Losing more than two inches in a single week, even during a heat wave, starts to look unusual. The next step is figuring out exactly how much your specific pool should lose, not just a citywide average.

Use the Chart for Your Pool Size and Conditions

A generic evaporation rate means little unless you match it to your pool's actual surface area. The next move is turning a general pool water evaporation chart into numbers that fit your backyard.

Pool size drives everything here. A small plunge pool loses far less total water than a large rectangular pool, even under identical weather. Surface area, not pool depth or volume, is the number that matters most for evaporation math.

The standard formula pool professionals use is straightforward: Gallons Lost = Surface Area (sq ft) × 0.62 × Inches Lost. Multiply your pool's length by its width to get surface area, then plug in the inches you measured.

• 10,000-gallon pool: about 620 gallons per inch of drop
• 15,000-gallon pool: about 930 gallons per inch
• 20,000-gallon pool: about 1,240 gallons per inch of drop
• 25,000-gallon pool: about 1,550 gallons per inch
• 30,000-gallon pool: about 1,860 gallons per inch

Convert Inches of Loss Into Gallons

Say your Marietta pool measures 32 feet by 16 feet, giving you 512 square feet of surface area. If the water dropped half an inch overnight, that is roughly 159 gallons lost in 24 hours.

That number only means something once you compare it to what evaporation alone should produce under the same weather. A pool evaporation calculator can speed up this math if you do not want to run the formula by hand.

Compare Weather Conditions With Your Actual Water Drop

Hot, dry, windy days push evaporation rates well above calm, humid ones, even in Georgia. A 90-degree day with low humidity and 10 mph wind can double or triple normal water loss compared to a still, muggy afternoon.

Track your actual drop for a few days and compare it against the ranges above for Marietta's typical summer conditions. If your numbers run consistently higher than the chart suggests, you need to look more closely at what's causing the gap.

What Makes Water Disappear Faster

Several environmental factors combine to speed up or slow down how fast your pool loses water, and none of them act alone. Understanding these factors helps explain a spike in evaporation before you assume the worst.

The temperature difference between your water and the surrounding air matters more than either number alone. A five-degree gap produces about 0.15 inches of daily loss, but a 20-degree gap can push that past 0.40 inches. Humidity then decides how much of that potential loss actually happens.

Heat, Humidity, and the Temperature Gap

Warmer water evaporates faster because heat gives water molecules the energy to escape into the air. At 70 percent humidity, evaporation slows by roughly 40 percent compared to dry air near 20 percent humidity.

Georgia's summer humidity usually sits in the moderate-to-high range, which helps keep local evaporation lower than in desert states. Saturated, moist air simply cannot absorb water vapor as quickly.

Wind, Sun, and Pool Activity

Wind speed has an outsized effect on evaporation, even in humid climates like Georgia. Winds above 10 mph can triple normal evaporation rates by constantly replacing the moist air layer just above the water with drier air.

Direct sun exposure heats the water surface directly, raising pool temperature and widening the gap with air temperature. Pools in open, unshaded backyards around Alpharetta and Johns Creek often show higher afternoon evaporation than nearby shaded pools.

Features and Splashing That Skew the Numbers

Water features like fountains and waterfalls add surface area exposed to air, increasing evaporation beyond the flat pool number. Splash-out from swimmers and pets also removes water that has nothing to do with evaporation or leaks.

If your pool sees heavy use or runs a water feature daily, factor that into your expectations before comparing numbers to a chart. None of these factors fully explain a leak, though, which is why a hands-on test matters next.

Confirm Evaporation With a 24-to-48-Hour Bucket Test

The bucket test gives you a direct comparison between evaporation and your pool's actual water loss. It works because both containers face the same sun, wind, and temperature during the test window.

This method has been the standard DIY check pool owners use before calling a professional. It will not tell you where a leak is, but it will clearly tell you whether one exists.

Set Up the 5-Gallon Bucket Correctly

Fill a 5-gallon bucket with pool water and set it on a pool step, keeping the outside and inside water levels even. Mark both levels clearly with tape or a marker.

Let the pump run on its normal schedule, then leave everything alone for 24 to 48 hours. Do not add water or skim the pool during that window, since disturbing either level ruins the comparison.

Read the Results Without Guessing

After 24 to 48 hours, check both marks side by side. If the pool water dropped by roughly the same amount as the bucket water, you are looking at ordinary evaporation.

• Pool and bucket drop by the same amount: normal evaporation, no leak indicated
• Pool drops noticeably more than the bucket: likely leak somewhere in the shell or plumbing
• Pool drops less with pump off than pump on: possible plumbing-side leak tied to circulation

Know When the Test Points to a Leak

A pool that loses visibly more water than the bucket, even by a quarter inch or more, points toward a real leak rather than weather. This gap holds true regardless of cyanuric acid levels or other chemical readings in your water.

The bucket test confirms that a leak exists, but it cannot show whether the source sits in the pool shell, the plumbing lines, or the filtration equipment. Finding that exact spot calls for equipment and experience beyond a homeowner's toolkit.

Reduce Normal Loss Without Hiding a Leak

Cutting normal evaporation saves water and money, but it should never mask a real leak. The goal is to trim the losses a pool water evaporation chart already predicts.

A pool cover remains the single most effective tool for this. According to EPA's WaterSense program, solid pool covers can reduce evaporation by more than 90 percent when in use, with some types cutting it by as much as 95 percent.

Cover the Water When the Pool Is Not in Use

Solar blankets and standard pool covers both trap surface moisture instead of letting it escape into the air. Even covering the pool overnight, when temperature gaps peak, makes a noticeable dent in monthly water loss.

Liquid solar covers offer a lighter-touch option for pools where a physical cover feels impractical. They will not match a solid cover's performance, but they still measurably reduce surface evaporation.

Block Persistent Wind Across the Surface

Windbreaks like fencing, hedges, or pergolas placed near the pool's edge slow air movement across the water surface. Since wind above 10 mph can triple evaporation, cutting surface wind speed has a real, measurable payoff.

Pools in open backyards around Roswell and Alpharetta tend to benefit most from this kind of wind protection. Even partial blocking on the prevailing wind side helps.

Manage Temperature and Water Features

Lowering your pool's target temperature by even a few degrees narrows the temperature gap driving evaporation. Running water features only when guests are swimming, rather than all day, also limits unnecessary surface exposure.

These steps trim the numbers your chart already predicts; they do not eliminate water loss caused by an actual leak. If your water keeps dropping past these fixes, the next step is confirming what the bucket test already suggested.

Schedule a Marietta Leak Inspection When the Numbers Do Not Match

A bucket test that shows your pool losing more water than plain pool water evaporation explains means it is time for an on-site look. Guessing at this stage usually costs more than getting an answer.

Marietta's mix of hot summers and occasional cold snaps stresses pool shells and plumbing in ways that are not always visible. A hairline crack or a failing pump shaft seal will not show up from the deck, no matter how carefully you inspect it.

Why a Confirmed Leak Needs On-Site Detection

Professional pool leak detection uses electronic listening equipment and pressure testing on plumbing lines to find leaks without guesswork. These tools locate problems in the shell, underground plumbing, or filtration system that a bucket test cannot pinpoint.

Waiting to confirm a leak usually makes the repair larger and more expensive over time. Water escaping under a deck or foundation can undermine soil and crack surfaces well beyond the original leak point.

Frequently Asked Questions

How Much Water Should Your Pool Lose to Evaporation on a Hot Day?

In Marietta's humid summer climate, expect one-eighth to one-quarter inch of daily loss on a hot day. Windy or unusually dry days can push that closer to three-eighths of an inch.

How Much Pool Water Evaporates When the Temperature Reaches 90 or 100 Degrees?

At 90 to 100 degrees with low humidity and wind above 10 mph, daily loss can reach half an inch or more. Georgia's typical humidity usually keeps totals closer to one-quarter to three-eighths of an inch even at those temperatures.

Is It Normal for Your Pool to Lose an Inch of Water Per Day?

No, an inch per day is well beyond normal evaporation for a Marietta-area pool, even during extreme heat. That level of loss almost always points to a leak and warrants a bucket test followed by professional inspection.

How Can You Tell Whether Your Pool Is Leaking or Losing Water to Evaporation?

Run a 24-to-48-hour bucket test comparing your pool's water drop to a bucket exposed to the same conditions. If the pool drops noticeably more than the bucket, you are likely dealing with a leak rather than plain evaporation.

How Does Pool Water Evaporation Change During Winter?

Cold air holds less moisture, which can actually widen the vapor pressure gap between pool water and air during dry winter spells. Uncovered pools can still lose measurable water in winter, even when the pool sits unused and temperatures stay low.

How Can You Calculate Your Pool's Evaporation Rate Based on Local Weather?

Use the formula Gallons Lost = Surface Area × 0.62 × Inches Lost, plugging in your pool's dimensions and measured water drop. Compare that figure against Marietta's typical daily and weekly ranges to see if your pool tracks normal or runs high.

Staring at the Waterline, Knowing What Comes Next

A pool water evaporation chart turns a confusing, worrying situation into a number you can actually check against. Once you know Marietta's typical daily and weekly ranges, a dropping waterline stops feeling like a mystery.

The bucket test takes the guessing out even further, giving you a clear yes or no on whether a leak exists. What it cannot do is show you where that leak is, and that is where professional equipment and on-site eyes matter.

Ready to stop guessing and start fixing? Get your free estimate from Atlanta Leak Pros and get it done right, whether you are in Marietta, Roswell, Alpharetta, or Johns Creek.