Can You Drink Swimming Pool Water in an Emergency? A Preparedness Guide to Treating Pool and Spa Water

When hurricanes, earthquakes, wildfires, winter storms, cyberattacks or prolonged power outages interrupt municipal water service, one of the largest reservoirs of water on a residential property may be sitting in plain sight: the swimming pool.

A typical backyard pool can contain 10,000 to 30,000 gallons of water. Even a modest spa may hold several hundred gallons. From an emergency-preparedness standpoint, that is an enormous resource.

But there is an important distinction:

Swimming pool water is not drinking water.

The Centers for Disease Control and Prevention (CDC) recommends using swimming pool and spa water for hygiene, cleaning and similar purposes—not drinking. In an emergency, bottled water and properly stored potable water should always be used first.

However, during a prolonged disaster in which conventional drinking-water supplies are exhausted or unavailable, a swimming pool may represent a valuable raw-water source that could potentially be treated. Whether that can be done safely depends on what is already dissolved in the water, how long the pool has been without treatment and, most importantly, the treatment technology available.

The chemistry matters.

A Swimming Pool Is a Reservoir—but Not a Cistern

A well-maintained swimming pool begins with water that, in most cases, originally met drinking-water standards. What changes that water are the chemicals subsequently added to maintain the pool.

Depending upon the system, the water may contain chlorine, bromine, cyanuric acid, sodium chloride, copper, algaecides, clarifiers, sequestrants, pH-adjustment chemicals and other dissolved substances.

It has also been exposed to swimmers, animals, insects, dust, pollen, leaves and potentially stormwater.

Therefore, making pool water microbiologically safe is only half of the problem. The other half is determining what dissolved chemicals need to be removed.

This is why the common survival advice to simply "boil pool water" can be dangerously incomplete.

Boiling Does One Job Very Well

Boiling is an excellent method of microbiological disinfection.

The CDC recommends bringing clear water to a rolling boil for at least one minute to kill disease-causing organisms. At higher elevations, additional boiling time is recommended.

But boiling does not remove most salts, metals or other dissolved chemicals.

The EPA specifically warns that boiling or disinfecting water will not destroy contaminants such as heavy metals, salts and most chemicals.

In fact, repeatedly boiling water without collecting and condensing the steam can concentrate nonvolatile dissolved contaminants because water evaporates while the contaminants remain behind.

This creates a critical preparedness rule:

Boiling addresses microorganisms. It should not be confused with chemical purification.

Distillation is different. In distillation, the steam is captured and condensed into a separate container. Proper distillation can remove microorganisms, sodium and many other dissolved contaminants, although certain volatile chemicals require additional consideration.

Chlorinated Pools

Traditional chlorine pools may actually begin an emergency in relatively good microbiological condition if the water was properly maintained immediately before power and chemical treatment stopped.

Chlorine is an effective disinfectant, but it is continuously consumed.

Sunlight, organic material, microorganisms and contaminants introduced into the water all contribute to chlorine demand. CDC notes that sunlight, dirt, sweat and other contaminants reduce chlorine concentrations.

Once circulation and chemical addition stop, therefore, the disinfectant residual eventually declines.

How quickly?

There is no responsible answer such as "three days" or "one week." It depends on chlorine concentration, cyanuric acid, sunlight, temperature, organic loading, rainfall, debris and whether the pool is covered.

A clear pool on Day 5 after a hurricane should not automatically be assumed microbiologically safe merely because it still looks clear.

If chlorine is the primary chemical concern and the water otherwise has acceptable dissolved-solids chemistry, activated carbon can be useful for reducing chlorine and many taste and odor compounds. But carbon treatment alone should not be treated as proof that water is microbiologically safe.

A sensible treatment train may require:

Sediment removal → activated carbon → appropriate microbial treatment/disinfection

depending upon the condition of the source water.

Brominated Pools and Spas

Bromine presents a somewhat different chemistry.

Bromine is commonly used in spas because it performs well under warm-water conditions. Like chlorine, however, its active disinfectant residual is not permanent. Once treatment stops, contamination and organic loading consume the active residual.

A spa also presents a special concern because its relatively small water volume, elevated temperature and high historical bather loading can make it a less desirable emergency drinking-water source than a large, well-maintained swimming pool.

If other water is available, spa water would generally be better reserved for sanitation, toilet flushing and other nonpotable purposes.

If brominated water must be considered as an emergency raw-water source, treatment should address both microbiological contamination and dissolved chemicals rather than relying on boiling alone.

Saltwater Pools: A Special Problem

"Saltwater" pools are actually chlorine pools.

A saltwater chlorine generator uses dissolved sodium chloride and electricity to generate chlorine. When the power goes out, chlorine generation stops—but the salt remains.

This is an important distinction during an emergency.

A typical saltwater pool contains thousands of milligrams per liter of dissolved salt. That concentration is far above what is normally encountered in freshwater drinking supplies.

The World Health Organization notes that sodium in potable water is commonly below 20 mg/L, although considerably higher concentrations can occur, and identifies approximately 200 mg/L as an average taste threshold rather than a health-based maximum.

Consequently, describing all salt-pool water as simply "toxic" because of sodium would be an oversimplification. The more important preparedness point is that its very high dissolved salt concentration makes conventional emergency filters and boiling unsuitable for desalination, and it can contribute a substantial sodium load.

Boiling does not remove the salt.

Activated carbon does not remove the salt.

A typical camping filter does not remove the salt.

To turn salt-pool water into low-TDS drinking water, a desalination process is required. Reverse osmosis is the most practical residential technology for accomplishing this.

CDC notes that RO can remove chloride and sodium as well as copper and numerous other contaminants.

The difficulty during an extended blackout is energy.

RO requires pressure. A normal under-sink RO system depends on pressurized feed water, while larger systems typically require an electric pump. A preparedness plan that depends on RO should therefore also include a means of powering or manually pressurizing that system.

Ionized Pools: A Different Emergency-Water Scenario

Copper-ionized pools deserve separate consideration.

Copper ionization maintains dissolved copper ions in the water. Unlike chlorine, copper does not simply disappear through evaporation or rapidly dissipate when electricity is lost.

That persistence can be advantageous from a water-storage perspective because a properly maintained copper residual may continue to provide antimicrobial and particularly algistatic activity after the ionization controller and circulation pump stop operating.

But persistence is also why copper concentration must be considered before drinking the water.

Copper is an essential nutrient, but excessive concentrations are undesirable in drinking water. EPA's drinking-water regulations use a copper action level of 1.3 mg/L.

Therefore, an ionized pool should not simply be declared potable because copper has helped suppress biological growth.

The encouraging part from an emergency-treatment standpoint is that copper is removable.

Reverse osmosis can substantially reduce copper along with many other dissolved contaminants.

Ionized water may consequently offer an interesting preparedness advantage: compared with a pool dependent entirely upon a rapidly declining halogen residual, its antimicrobial metal residual does not disappear simply because the power has failed.

That does not eliminate the need for final treatment before consumption.

What About a Sawyer Filter?

Portable hollow-fiber filters are extremely valuable preparedness tools, but understanding what they do—and what they do not do—is essential.

For example, Sawyer Products states that its 0.1-micron Squeeze filtration technology removes bacteria and protozoa such as Giardia and Cryptosporidium.

That makes this type of filter extremely useful when electrical power is unavailable.

But it is not a desalination or chemical-removal device.

Sawyer specifically states that its filters do not remove metals, chemicals, pesticides, hydrocarbons or salt. Dissolved substances pass through the hollow-fiber membrane.

That means a Sawyer-type filter should not be expected to remove:

• Sodium chloride from a salt pool

• Dissolved copper from an ionized pool

• Most dissolved pool-treatment chemicals

• Other dissolved salts contributing to TDS

This distinction is fundamental.

Microfiltration and desalination are two very different processes.

A portable filter can be excellent protection against certain microorganisms while doing virtually nothing to reduce dissolved sodium.

Reverse Osmosis Is the Most Comprehensive Practical Option

For swimming-pool water containing significant dissolved contaminants, reverse osmosis offers one of the most capable treatment technologies available to homeowners.

RO uses pressure to force water through a semipermeable membrane while rejecting a large percentage of dissolved contaminants.

EPA identifies RO as capable of removing a wide range of inorganic contaminants, dissolved solids and other substances and notes that RO can be used for desalinating brackish or seawater.

For emergency pool-water treatment, an ideal treatment train might look something like:

Pool → sediment prefilter → activated carbon → reverse osmosis → final microbial barrier/disinfection → clean covered storage

Activated carbon protects the RO membrane and reduces many organic compounds and oxidants. RO addresses dissolved salts and metals. A final microbiological barrier provides additional protection against organisms and contamination introduced downstream.

The weakness is obvious: conventional RO requires pressure and usually electricity.

For serious emergency preparedness, therefore, consider whether the treatment system can operate from a generator, battery/inverter, solar-powered pump or manually operated high-pressure pump.

A sophisticated water-treatment system that cannot operate without the electrical grid may have little value on Day 10 of a blackout.

Should You Cover the Pool?

For emergency water preservation, a pool cover can be extremely valuable.

A cover reduces the introduction of leaves, insects, animal waste, airborne debris and other organic contamination. It can also reduce sunlight exposure, which helps slow chlorine degradation and algae growth.

Reducing evaporation preserves water as well.

There are disadvantages.

A cover does not sterilize the pool. If microorganisms and nutrients are already present, biological activity can continue underneath it. A cover may also create a false sense that the water remains safe simply because it looks clean.

There is also an important safety consideration: an improvised tarp is not a safety-rated pool cover and can create a serious drowning hazard.

From a water-preservation standpoint, however, a properly designed pool cover is generally an advantage during a prolonged emergency.

How Long Will Stagnant Pool Water Remain Usable?

This may be the most important question—and the one least suited to a fixed number of days.

There is no universal expiration date for stagnant swimming-pool water.

A covered 20,000-gallon pool that began clean and properly disinfected will behave very differently from an uncovered pool exposed to 90°F temperatures, intense sunlight, rain, leaves, animals and flood debris.

The more useful concept is source-water deterioration.

First Stage: Recently Maintained Water

Immediately following loss of power, a properly maintained pool may still have active disinfectant residual and relatively low microbial loading.

This is the best condition from which to begin preserving the water.

Second Stage: Declining Residual

As chlorine or bromine is consumed, the water loses its primary disinfectant barrier.

The water may still look perfectly clear.

Appearance should never be used as proof of microbiological safety.

Third Stage: Stagnation

Without circulation, filtration and adequate disinfectant, microorganisms can multiply and algae may begin growing. Debris accumulates and organic loading increases.

At this point the pool should increasingly be viewed like a pond or other untreated surface-water source rather than like treated swimming water.

Fourth Stage: Gross Contamination

If floodwater, sewage, fuel, pesticides or other hazardous chemicals enter the pool, the situation changes completely.

Do not assume ordinary emergency treatment can make chemically contaminated pool water safe.

CDC specifically warns that water containing fuels or toxic chemicals cannot be made safe simply through boiling or disinfection. Another water source should be used.

This is particularly important following hurricanes and flooding.

A Better Emergency Strategy: Protect the Water Before You Need It

The best time to think about your swimming pool as an emergency water reserve is before the emergency.

If a major hurricane or extended outage is approaching, the objective should be to begin with the cleanest possible reservoir.

Make sure the pool is properly balanced and sanitized. Remove debris. Clean the filter. Avoid unnecessary chemical additions immediately before the emergency. If practical, cover the pool before storm debris begins falling.

Most importantly, store actual drinking water first.

FEMA-style emergency planning should begin with dedicated potable water. Pool water should represent a large secondary resource, not the first bottle you reach for.

A household with a pool might therefore think of its emergency water in three categories:

Tier 1 – Stored potable water: Bottled water and properly stored drinking water for immediate consumption.

Tier 2 – Pool water for nonpotable use: Toilet flushing, cleaning and other appropriate sanitation uses, preserving potable supplies.

Tier 3 – Pool water as an emergency raw-water source: Water subjected to treatment appropriate for its microbiological and chemical characteristics when safer supplies are exhausted.

That distinction can dramatically extend a household's emergency water resilience.

Choosing Treatment Based on Pool Type

Pool Type	Primary Emergency Concern	Boiling	Sawyer-Type Filter	Activated Carbon	Reverse Osmosis
Chlorine	Microorganisms after residual disappears; dissolved pool chemicals	Kills microbes; does not remove most chemicals	Removes bacteria/protozoa, not dissolved chemicals	Useful for chlorine and many organics	Broad chemical/TDS reduction
Bromine	Bromine chemistry, microbes, spa contamination	Microbial treatment only	Microbial barrier only	Useful component of treatment train	Strong option
Saltwater	High sodium/chloride/TDS plus microbes	Does not remove salt	Does not remove salt	Does not remove salt	Preferred desalination technology
Copper ionized	Copper concentration plus microbial risk	Does not remove copper	Does not remove dissolved copper	Limited for dissolved copper	Can substantially reduce copper/TDS
Unknown/neglected pool	Microbes + unknown chemicals	Insufficient by itself	Insufficient by itself	Insufficient by itself	Potentially useful, but water should be evaluated
Flood/chemical-contaminated pool	Fuel, pesticides, sewage or unknown hazardous chemicals	Do not rely on it	Do not rely on it	Do not rely on it	Seek another source unless professionally evaluated

Electricity Changes Everything

Emergency preparedness has a habit of exposing the difference between laboratory capability and practical capability.

A treatment technology may be capable of producing excellent drinking water, but that does little good if it requires 120-volt power during a two-week grid failure.

For that reason, every household emergency water plan should ask four questions:

What can I operate with no electricity?

Gravity filters, portable hollow-fiber filters, chemical disinfectants and boiling over an alternative heat source can remain functional without grid power.

What requires pressure?

Reverse osmosis needs sufficient feed pressure. If RO is central to the plan, determine beforehand how that pressure will be produced.

What removes microorganisms?

Boiling, appropriate disinfection and certified microbial filtration can address different microbiological hazards.

What removes dissolved chemicals and salts?

That requires an entirely different level of treatment. A 0.1-micron camping filter cannot perform the job of reverse osmosis simply because both devices are called "water filters."

The Most Important Rule: Know What You Are Trying to Remove

There is no universal "emergency water filter."

Water treatment is a series of barriers selected for specific contaminants.

Sediment filtration removes particles.

Microfiltration can remove many microorganisms.

Activated carbon can reduce chlorine and numerous organic contaminants, tastes and odors.

Boiling kills microorganisms.

Reverse osmosis removes many dissolved salts, metals and chemicals.

Distillation separates water from many dissolved contaminants.

Chemical disinfection kills susceptible microorganisms but does not remove salt or heavy metals.

Understanding those distinctions can mean the difference between water that merely looks clean and water that has actually been treated for the hazards present.

The Swimming Pool as an Emergency Asset

A 20,000-gallon swimming pool represents roughly 160,000 pounds of stored water sitting in the backyard.

That deserves consideration in any serious household preparedness plan.

It should not be labeled an automatic source of drinking water. Public-health guidance is clear that untreated pool and spa water should not normally be consumed. But neither should thousands of gallons of potentially treatable water be ignored during planning for a prolonged emergency.

The right question is not:

"Can I drink my swimming pool water?"

The better question is:

"What is in my swimming pool water, and what treatment barriers would be required to turn that particular water into an appropriate emergency drinking-water source?"

For a traditional chlorinated pool, the challenge may eventually become primarily microbial plus residual pool chemistry.

For a brominated spa, both chemical composition and microbiological history deserve greater caution.

For a saltwater pool, desalination becomes the defining challenge.

For an ionized pool, the persistence of copper may help provide a longer-lasting antimicrobial barrier during loss of power, but copper concentration must ultimately be brought into an acceptable range if the water is intended for consumption.

And for any pool contaminated by floodwater, sewage, petroleum products or unknown chemicals, the safest decision may be not to use it for drinking at all.

Preparedness is not about assuming that water is safe.

It is about having the knowledge, equipment and treatment barriers necessary to make an informed decision before the faucet stops running.

Preparedness Takeaway

A swimming pool should be viewed as an emergency water reservoir, not an emergency drinking-water tank.

Preserve it. Cover it when practical. Keep contamination out. Know its chemistry. Have treatment equipment that works without the electrical grid. Reserve untreated pool water for nonpotable purposes whenever possible, and use stored potable water first.

If circumstances ever make the pool your last major source of water, the treatment method must be selected according to the contaminants actually present—not simply according to whether the finished water looks clear.

Before an Emergency, Talk With a Water Treatment Professional

The worst time to determine whether your emergency water-treatment plan will work is after the power is out and your normal drinking-water supply has been interrupted. Pool chemistry, source-water quality and treatment requirements can vary significantly, particularly among chlorine, bromine, saltwater and copper-ionized pools. Before relying on a swimming pool or spa as part of an emergency water plan, consult an experienced water treatment professional who can evaluate the water chemistry and recommend an appropriate combination of sediment filtration, activated carbon, microbiological treatment, reverse osmosis or other technologies. Just as importantly, discuss how that equipment will operate if electricity and normal water pressure are unavailable.

Intec America has worked with residential, commercial and specialized water-treatment applications for decades and offers technologies including filtration, reverse osmosis, ultraviolet treatment, ozonation and copper ionization. Whether you are preparing for hurricanes, extended power outages or another disruption to the public water supply, developing the treatment strategy before the emergency occurs can turn a large stored water source into a far more useful preparedness asset.

For assistance evaluating your emergency water-treatment needs, visit Intec America Corporation or contact Intec America at 800-896-1759 to discuss a treatment system appropriate for your water source and preparedness objectives.