Do Pools Waste Water? The Truth About Pool Ownership and Water Conservation in Northern California

Many Californians assume pools waste water, but the facts tell a different story. Here's what Sacramento homeowners should know about pools, drought, and responsible water stewardship.

For homeowners in California, water use is never far from mind. Years of drought, ongoing water restrictions, and a genuine cultural commitment to conservation have made many Northern California residents hesitant about installing a swimming pool. 

The assumption is understandable: a pool is a large body of water sitting in the backyard ... surely that must be wasteful.

The facts tell a surprising story. Here's what the research actually shows about pools and water use, and why a fiberglass pool from Sierra Fiberglass Pools may be one of the most water-responsible backyard investments you can make.

The Biggest Misconception About Pools and Water

The most widespread misconception about swimming pools is that they continuously consume enormous volumes of water. In reality, a properly maintained pool is a closed-loop system. Once filled, the water stays in the pool and is continuously recirculated, filtered, and reused. The pool is not running water down a drain; it's holding and recirculating the same water, often for an entire season or longer without needing significant replenishment.

Water loss from a pool comes primarily from two sources: evaporation and splashout. Both can be meaningfully reduced through straightforward practices. As a result, a well-maintained pool uses far less water over time than most homeowners assume.

Pools vs. Lawns

A compelling data point in the pool-versus-drought debate comes from a direct comparison of pool water use against lawn irrigation, because for most homeowners, replacing a lawn with a pool is effectively the trade-off being considered.

According to research compiled by the Pool & Hot Tub Alliance, independent studies show that the average swimming pool installation uses one-third of the water that a lawn of the same square footage requires. A pool's surrounding deck area (concrete, pavers, or other hardscape) replaces grass that would otherwise require regular irrigation. When you account for both the pool itself and the non-irrigated decking that replaces lawn, the water savings compared to maintaining a comparable lawn area are substantial.

The numbers are striking: lawn irrigation requires approximately 49 inches of water per year. A swimming pool requires about 39.6 inches per year, and when you subtract the deck area that replaced lawn, the pool's effective water use drops to about 20 inches per year. That's less than half the water a lawn of the same footprint would consume.

Even more surprising, building and filling a brand-new pool requires less water in its first year than maintaining a lawn of comparable size. Filling a new pool requires an average of approximately 32,000 gallons of water, while a 1,200-square-foot lawn consumes approximately 44,000 gallons per year just in irrigation. In the first year alone, a new pool saves approximately 12,000 gallons compared to the lawn it replaces. Each subsequent year, the savings average about 30,000 gallons per pool.

For Sacramento-area homeowners weighing the water-responsibility question, these numbers reframe the conversation. From a water-consumption standpoint, removing a lawn and installing a pool is one of the most conservation-positive backyard changes you can make.

The Impact of Pool Water on a Community's Water Supply

Another perspective that helps put pool water use in context is the scale of pool water consumption relative to a water district's total supply. A research project conducted in the Santa Clara Valley found that if 800 pools were built in a typical year and each were filled with 20,000 gallons of water, the total water required for all of those pools would equal just 4.5% of a single day's average water use for that water district — or roughly one hour of typical public water consumption.

In other words, even in a region with active pool construction, the total water drawn by all new pools combined is negligible relative to overall water district supply. Singling out pools as a significant contributor to regional water scarcity is not supported by the data.

Why Fiberglass Pools Are the Most Water-Efficient Pool Type

Not all pools manage water equally well, and fiberglass pools have meaningful built-in advantages over concrete and vinyl, making them a more water-responsible choice.

Fiberglass pools retain heat more efficiently than concrete pools because the fiberglass shell insulates. Water temperature is one of the primary drivers of evaporation; warmer water evaporates faster, and water that loses heat more rapidly requires more energy and more chemical treatment to maintain. Because a fiberglass pool holds its heat longer, it loses less water to evaporation than a comparable concrete pool over the course of a season.

The non-porous gelcoat surface of a fiberglass pool also means the shell doesn't absorb water the way concrete does. Concrete pool shells are inherently porous, and a small but meaningful amount of water is absorbed into the shell material itself over time. Fiberglass is inert; it neither absorbs water nor leaches minerals into it.

Additionally, fiberglass pools require up to 50% fewer chemicals than concrete pools. Chemicals don't directly affect water volume, but backwashing (used to clean sand and DE filters common with concrete pools) does consume water. Fiberglass pools are typically paired with cartridge filtration systems that don't require backwashing, eliminating that source of water loss entirely.

Practical Water Conservation Tips for Pool Owners

For pool owners who want to minimize water use as much as possible, there are several highly effective practices worth adopting. These apply whether you're already a pool owner or planning a new installation.

Using a pool cover is the single most impactful thing you can do to reduce pool water loss. Evaporation is dramatically accelerated when the pool surface is exposed to direct sun, wind, and dry air, all of which are features of Sacramento summers. A solar cover, mesh safety cover, solid safety cover, or automatic cover significantly reduces evaporation by keeping the water surface protected when the pool is not in active use. Sierra Fiberglass Pools offers a full range of pool cover options — learn more at sierrafiberglasspools.com/covers.

Minimizing splashout — the water that leaves the pool through active use, particularly from diving, jumping, and vigorous swimming — is worth thinking about from a design perspective. Positioning the pool so that splashout falls onto the deck and can drain back toward landscaping rather than being lost entirely is a small but worthwhile consideration. Reducing pool water level slightly during periods of heavy use also helps.

Turning off water features like fountains, deck jets, and waterfalls when the pool is not in active use reduces surface agitation and evaporation. Water features create increased water surface area and movement, both of which accelerate evaporation. Running them only when the pool is occupied maximizes enjoyment while minimizing water loss.

Rainwater collection is another strategy that is particularly relevant for the Sacramento region, which receives meaningful rainfall during the winter months. Pool covers with mesh designs or solid covers with pump systems can collect rainwater that can be used to top off the pool rather than drawing from municipal supply. Extending downspouts from the house toward the pool area during the rainy season allows rainwater to supplement pool water levels naturally.

Keeping the pool water balanced properly also reduces how frequently the pool needs to be partially drained and refilled. Imbalanced water chemistry is one of the primary reasons pools need water changes. Consistent chemical maintenance extends the life of the water in the pool and reduces refill frequency.

A Note on Outdoor Water Use in Context

The drought conversation in California often focuses narrowly on pools while overlooking the broader picture of outdoor water consumption. Outdoor water use accounts for more than 30% of total household water consumption on average — and in arid regions like the Sacramento Valley, that figure can approach 60% during summer months. Most of that outdoor water use goes to lawn and garden irrigation, not pools.

Homeowners who are genuinely motivated by water conservation can make a far larger impact by converting high-water-demand lawns to drought-tolerant landscaping, upgrading to drip irrigation systems, fixing leaky faucets and toilets (which lose an average of 10 gallons per household per day) and running appliances on full loads than by forgoing a pool.

A fiberglass pool surrounded by thoughtful drought-tolerant landscaping and protected by a quality pool cover is one of the most water-responsible backyards a Northern California homeowner can build. The data supports it.

Visit sierrafiberglasspools.com or call (916) 537-6540 to learn more and start your free estimate. Learn more about water conservation at https://letspooltogether.com.

Frequently Asked Questions

Do swimming pools waste water in California?
No. Research shows that a well-maintained swimming pool uses approximately one-third of the water that a lawn of the same square footage requires when you account for the deck area that replaces grass. Even filling a new pool in its first year requires less water than maintaining a comparable lawn. A fiberglass pool surrounded by drought-tolerant landscaping and covered when not in use is one of the most water-efficient backyard investments a California homeowner can make.

How much water does a swimming pool use per year?
A swimming pool requires approximately 39.6 inches of water per year. When you subtract the surrounding deck area that replaces lawn, which would otherwise require irrigation, the effective water use drops to approximately 20 inches per year, compared to 49 inches per year for lawn irrigation. On an ongoing basis, a pool saves approximately 30,000 gallons per year compared to a lawn of equivalent square footage.

How do I reduce water evaporation from my pool?
The most effective way to reduce pool water evaporation is to use a pool cover whenever the pool is not in active use. Solar covers, solid safety covers, mesh covers, and automatic covers all significantly reduce evaporation by protecting the water surface from sun, wind, and dry air. Turning off water features when the pool is unoccupied, reducing the pool water temperature slightly, and maintaining proper water chemistry also help minimize evaporation.

Is it wasteful to build a new pool during a California drought?
Building a new pool requires an average of approximately 32,000 gallons of water for the initial fill. By comparison, a 1,200-square-foot lawn consumes approximately 44,000 gallons per year in irrigation. This means that even in its first year, a new pool uses less water than the lawn it replaces, and in every subsequent year, the savings continue. The total water used to fill all new pools in a typical regional water district equals just about one hour of average public water consumption for that district.

Are fiberglass pools more water-efficient than concrete pools?
Yes. Fiberglass pools are more water-efficient than concrete pools in several ways. Fiberglass retains heat more efficiently, which reduces evaporation from the pool surface. The non-porous fiberglass shell does not absorb water the way porous concrete does. And fiberglass pools are typically paired with cartridge filtration systems that do not require backwashing, eliminating a source of water loss that is common with the sand and DE filters often used with concrete pools.

Can I use rainwater to top off my pool?
Yes. Rainwater collected from pool covers or redirected from roof downspouts can be used to supplement pool water levels, reducing reliance on municipal water supply. Mesh safety covers allow rain to pass through and accumulate in the pool naturally. Solid covers collect rainwater that can be pumped into the pool. For Sacramento-area homeowners who experience meaningful winter rainfall, this is a practical and conservation-minded way to maintain pool water levels throughout the year.

Does a pool cover really make a difference for water conservation?
Yes, significantly. Evaporation is the primary source of water loss in a residential pool, and it is dramatically accelerated when the pool surface is exposed to direct sun, wind, and low humidity — all common conditions during Sacramento summers. A quality pool cover can reduce evaporation by as much as 95% when the pool is covered. Over the course of a full season, this can represent thousands of gallons of water saved. Sierra Fiberglass Pools offers a full range of cover options at sierrafiberglasspools.com/covers.

What is the most water-efficient pool filtration system?
Cartridge filter systems are the most water-efficient pool filtration option because they do not require backwashing (the process of reversing water flow through a sand or DE filter to clean it), which sends a significant volume of water to waste. Cartridge filters are cleaned by removing the cartridge and rinsing it with a garden hose, using a small fraction of the water that backwashing requires. Fiberglass pools are commonly paired with cartridge filtration systems, which contributes to their overall lower water consumption compared to concrete pools.