If your home has a swimming pool, it accounts for the single largest concentrated water use on your property. That’s typically 15,000 to 35,000 gallons just to fill, and another 5,000 to 12,000 gallons in evaporation and refilling each season. For homes in hot, dry climates, pool-related water use can exceed all other outdoor water uses combined.
The single biggest mistake pool owners make isn’t dramatic. It’s not running the pump too long, or backwashing the filter unnecessarily, or any of the technical issues. It’s simply not using a pool cover when the pool isn’t in use.
An uncovered pool loses water to evaporation continuously. The rate varies with weather (temperature, wind, humidity, sun exposure), but a typical uncovered backyard pool in a hot climate loses 1,000 to 2,500 gallons per month during summer. A pool cover reduces that loss by 90 to 95 percent, according to U.S. Department of Energy guidance on pool covers.
The evaporation math
The amount of water a pool loses to evaporation depends on:
- Surface area (larger pools lose more)
- Water temperature (warmer means more evaporation)
- Air temperature (warmer means more evaporation)
- Wind exposure (windy days lose much more)
- Humidity (dry air pulls more moisture off the surface)
- Sun exposure (direct sun raises the loss rate)
| Conditions | Approximate evaporation rate | Annual loss (typical pool) |
|---|---|---|
| Hot, dry, windy (Phoenix-like) | 0.25 to 0.4″ per day | 20,000 to 35,000 gal |
| Hot, humid (Houston-like) | 0.15 to 0.25″ per day | 10,000 to 18,000 gal |
| Moderate (most U.S.) | 0.10 to 0.20″ per day | 7,000 to 14,000 gal |
| Mild, with cool nights | 0.05 to 0.15″ per day | 3,500 to 10,000 gal |
The pool cover changes everything. A solar cover (the most common type) cuts evaporation by 90 to 95 percent and also reduces heat loss overnight, saving energy on pool heaters. The USGS Water Science School explanation of evaporation is a useful primer for anyone who wants to understand why a warm, exposed water surface loses volume so quickly.
The cover types
Solar covers (bubble covers)
The blue or clear bubble-wrap looking covers that float on the water surface. Inexpensive ($50 to $200), easy to use, but require manual installation and removal. Best for pools used regularly.
Automatic covers
Powered roll-up covers built into the pool deck. Press a button to cover or uncover. Expensive ($5,000 to $15,000) but convenient and effective. Best for new pool installations or major renovations.
Mesh safety covers
Heavy-duty covers anchored to the deck, often used as winter covers. They reduce evaporation modestly, but their primary purpose is safety.
Liquid pool covers
Chemical additives that form a one-molecule-thick layer on the water surface. Less effective than physical covers but easier to use. Save about 30 to 50 percent of evaporation.
Why pool owners don’t cover
Despite the obvious water and energy savings, many pool owners don’t use covers. Common reasons:
- The cover is annoying to put on and take off
- The pool looks better uncovered
- The cover gets dirty and needs maintenance
- Someone might want to use the pool spontaneously
- The pool has an unusual shape that makes covers difficult
The first reason is the most common. The friction of cover installation is real. For a manual cover on an in-ground pool, it can take 5 to 10 minutes to put on and another 5 to 10 to take off. Done twice a day, that’s 20+ minutes daily, which most people quickly stop doing.
The automated cover argument
For pool owners genuinely committed to conservation, an automated cover changes the math. The button-push installation removes the friction entirely. Most pool owners with automated covers use them consistently because it’s no harder than turning off a light.
Cost: $5,000 to $15,000 installed. Payback in pure water savings: 5 to 10 years in dry climates, longer in mild ones. The energy savings (less heating loss) often add another 30 to 50 percent to the payback equation.
For households building a new pool or doing a major renovation, an automated cover is one of the highest-return upgrades available. For existing pools, retrofit is possible but more expensive.
Other pool water waste sources
Beyond evaporation, several smaller issues add up.
Backwashing too often
Sand and DE filters need periodic backwashing, but many pool owners do it too often. Each backwash uses 100 to 300 gallons. Once a month is typically enough; weekly is excessive.
Pool leaks
A pool can lose surprising amounts of water through cracks, pipe fittings, or skimmer and return fittings. If your pool needs unusually frequent topping off, suspect a leak.
The “bucket test” diagnostic:
- Fill a 5-gallon bucket with pool water.
- Set it on the top step of the pool.
- Mark the water levels in both the bucket and the pool with tape.
- Wait 24 hours.
- Compare drop rates. If the pool dropped significantly more than the bucket, there’s a leak.
Children’s splashing
Active pool use splashes meaningful amounts of water out of the pool. A busy pool day can lose 100 to 500 gallons to splashing. Not much can be done about this except adjusting water level expectations.
Pool deck rinsing
Hosing down the pool deck wastes substantial water if done with a running hose. Sweep first, spot-clean only what needs it.
The conservation-minded pool routine
A pool owner serious about water conservation typically:
- Uses a cover when the pool isn’t in use (the single biggest factor)
- Maintains water level slightly below the typical full line (less surface area when evaporation peaks)
- Plants wind breaks around the pool to reduce wind-driven evaporation
- Backwashes the filter only when needed, not on a schedule
- Tests for leaks annually with the bucket test
- Times the pool pump for shorter cycles during cool seasons
This routine can cut a pool’s seasonal water demand by 30 to 50 percent without affecting how the pool is used.
The pool decision overall
For households in dry climates, a pool is a significant water commitment. The cover, alone, is the difference between a pool that’s a major water consumer and one that’s a modest one.
If you have a pool, use a cover. If you’re considering installing a pool, plan for the cover from day one. An automated cover built into the original installation is dramatically less expensive than retrofitting later.
The pool itself isn’t inherently wasteful. Uncovered, it becomes one. The fix is so simple that the only real explanation for not doing it is friction, which is solvable.
How pool covers fit the household you actually have
One pattern that comes up across nearly every conservation conversation we have with readers: the practices that stick are the ones that match how the household already lives. A pool cover you have to wrestle onto the water for ten minutes at 10 p.m. is a cover that stops getting used by August. That is the honest failure mode, not a lack of commitment.
For pool households, the version of cover that fits the routine matters more than the theoretical best cover. A solar cover on a reel that one person can pull across in thirty seconds gets used. A liquid additive that a spouse pours in every two weeks gets used. An automatic cover built into the deck at construction time gets used. A folded tarp that requires two adults to spread out does not, no matter how good its numbers look on paper.
Pick the covering method the pool’s regular users will accept without complaint, and the water savings show up in the bill within a single season. Consistency across the summer beats a technically perfect cover that spends most of its life on the shed floor.
