Pool water can serve as an emergency drinking water source, but it requires treatment before you swallow it. The chemical cocktail in a typical swimming pool, while designed to keep the water safe for swimming, includes disinfection byproducts, stabilizers, and sometimes metals that are not meant to be ingested in quantity. In a genuine survival scenario where no tap water, bottled water, or natural freshwater is available, pool water is a far better starting point than seawater or stagnant puddles. Getting it from “swimmable” to “drinkable” takes some understanding of what you are actually dealing with and a few practical steps.
What Is Actually in Pool Water
The water in a maintained swimming pool is not just Hâ‚‚O plus chlorine. It contains a layered mix of intentional additives and unintentional contaminants, and each category creates its own challenge for someone trying to drink it.
The intentional side starts with the disinfectant itself, usually chlorine in the form of sodium hypochlorite, calcium hypochlorite, or chlorine gas dissolved in water. Free chlorine in a well-maintained pool typically sits between 1 and 3 parts per million (ppm). Many outdoor pools also use cyanuric acid as a stabilizer to prevent sunlight from breaking down free chlorine too quickly. While cyanuric acid helps maintain germicidal effectiveness, excessive concentrations have been flagged as a potential health concern.
Then there are the chemicals nobody added on purpose. When chlorine reacts with organic matter in the water, it produces disinfection byproducts (DBPs). The best-known groups are trihalomethanes (THMs) and haloacetic acids (HAAs). Pool water tends to contain more types of DBPs and at higher concentrations than drinking water because the organic matter in pools includes not just leaves and dirt but sweat, urine, skin cells, sunscreen, and lotions from swimmers.
DBPs have been linked to health effects including respiratory problems and, with long-term exposure, an elevated risk of bladder cancer.
Finally, pools may harbor microorganisms. Even properly chlorinated water can contain pathogens that resist normal disinfectant levels. Cryptosporidium and Legionella are among the most frequently reported pathogens in swimming-pool-associated disease outbreaks.
Why You Should Not Just Drink It Straight
A common assumption is that because pool water is already disinfected, it is essentially clean enough to drink. The reality is more complicated. Municipal drinking water is treated to meet strict standards for dozens of chemical contaminants, and the treatment process is designed specifically to minimize DBPs. Pool water treatment has a completely different goal: keeping microbial counts low enough that swimmers do not get sick from incidental swallowing or skin contact. Nobody optimizes pool chemistry for ingestion.
The chlorine concentration in a typical pool, while within a range that will not harm you from incidental swallowing during a swim, can cause nausea, stomach cramps, and throat irritation if you drink several glasses of it. Cyanuric acid, common in outdoor pools using stabilized chlorine products, adds another layer. In pools where it has been allowed to build up (sometimes reaching hundreds of ppm in poorly managed pools), drinking the water introduces a compound your body does not need and cannot easily process in large amounts.
The disinfection byproduct situation is where things get genuinely concerning. Compared to drinking water, pool water is a more complicated chemical matrix. The additional human inputs to pool water, including body fluids and personal care products, lead to greater concentrations and more diverse types of DBPs than you would find in treated tap water.
And while chlorine handles many bacteria and viruses, Cryptosporidium is notoriously resistant to chlorine at normal pool concentrations. An outbreak-causing dose can survive for days in a properly chlorinated pool. So “the pool has chlorine in it” does not guarantee microbiological safety for drinking.
Removing or Reducing Chlorine
The first practical step in making pool water drinkable is dealing with the free chlorine. At 1 to 3 ppm, the chlorine level in pool water is higher than what most municipal systems deliver to your tap (often around 0.2 to 1.0 ppm at the faucet). You want to bring it down, but not eliminate it entirely until you are about to drink, because the chlorine is still protecting you from microbial growth while the water sits.
The simplest method available in an emergency is off-gassing. Chlorine is volatile. If you fill an open container with pool water and let it sit in sunlight for several hours, the free chlorine will dissipate on its own. Stirring or aerating the water speeds this up. In direct sun with some agitation, you can reduce free chlorine substantially within a few hours. This works less well if the pool uses stabilized chlorine (with cyanuric acid), because the stabilizer’s whole purpose is to slow chlorine breakdown.
Chemical dechlorination is another option if you happen to have the right supplies. Ascorbic acid (vitamin C) neutralizes chlorine effectively: crushing a vitamin C tablet into a gallon of pool water will react with the free chlorine almost instantly. Sodium thiosulfate, sometimes found in aquarium supply kits, also works. A study comparing dechlorination agents found that ascorbic acid, sodium bisulfite, and sodium thiosulfate all neutralize chlorine, though they differ in how they affect the water’s pH and dissolved oxygen.
If you have none of those, boiling pool water for one minute will drive off free chlorine and kill most pathogens simultaneously, making it a good dual-purpose step. Boiling will not remove cyanuric acid or most DBPs, but it handles chlorine and microbes in one go.
Dealing with Disinfection Byproducts
This is the harder problem. THMs and HAAs do not boil off as easily as free chlorine, and they are not visible or easily detectable without test equipment. In a true emergency, you are unlikely to have laboratory-grade filtration on hand, but understanding the options helps you improvise.
Activated carbon filtration is the most accessible technology for reducing DBPs. A standard household water pitcher with a carbon filter (the kind you might already own for tap water) will reduce THMs and some other volatile organic compounds. Granular activated carbon has been studied for use in pool water treatment systems, where it removes chloramines and certain byproducts, though its effectiveness depends on contact time, pore size, and how fresh the carbon is.
If you have access to a more robust filtration system, reverse osmosis membranes are highly effective. Research on removing haloacetic acids from pool water found that tight reverse osmosis and nanofiltration membranes achieved rejection rates of 90% or higher for HAAs under typical pool water conditions.
For most emergency scenarios, though, your realistic options come down to a combination of letting chlorine off-gas, running the water through whatever carbon filter you have, and accepting that some DBP exposure over a short period is a manageable tradeoff compared to dehydration.
Killing What Chlorine Missed
If the pool has been sitting without maintenance, if power is out and the circulation pump is down, or if the emergency has lasted long enough that chlorine levels have dropped to zero, microbial contamination becomes the primary threat. Stagnant pool water can become a breeding ground for bacteria, algae, and protozoa.
Boiling remains the gold standard for field-expedient water purification. A rolling boil for one minute (three minutes above 6,500 feet elevation) kills virtually all pathogens, including Cryptosporidium, which resists chlorine but cannot survive sustained high temperatures. If you have fuel to boil water, this is your most reliable step.
UV exposure is another option. Leaving clear water in transparent plastic bottles in direct sunlight for six or more hours (a method known as solar disinfection, or SODIS) can inactivate many pathogens. This works best with clear water; if the pool has turned green with algae, you would need to filter out the particulates first using cloth, coffee filters, or improvised sand filtration before solar treatment can work effectively.
If you have household bleach (unscented, 5-8% sodium hypochlorite) and the pool’s chlorine has depleted, you can re-dose the water yourself. Two drops per liter of clear water, mixed well and left for 30 minutes, brings the chlorine to a level that kills most bacteria and viruses. This will not handle Cryptosporidium, though, so boiling is still preferable if you can manage it.
What About Saltwater Pools
Saltwater pools add a wrinkle. These systems generate chlorine on-site by running salt (sodium chloride) dissolved in the pool water through an electrolytic cell. The salt concentration in a typical saltwater pool is around 3,000 to 4,000 ppm, which is roughly a tenth of ocean water but still noticeably salty. For comparison, drinking water standards generally recommend less than 500 ppm of total dissolved solids.
Drinking saltwater pool water in small quantities during an emergency will not harm you the way drinking seawater would. The salt level is low enough that your kidneys can handle it. But the elevated sodium means your body will need more fresh water to process it, which partially defeats the purpose if you are already dehydrated. If you have a choice between a conventional chlorine pool and a saltwater pool, the conventional pool is generally the better emergency water source because of the lower dissolved solids.
Removing salt requires distillation or reverse osmosis, neither of which is practical in most emergency settings. You can improvise a basic solar still using a pot, a lid, and a collection container (heat the water, collect the condensation), which will leave the salt behind along with most other dissolved contaminants. This is slow but effective if you have time and sunlight or fuel.
Pools Treated with Bromine or Biguanide
Not all pools use chlorine. Bromine is common in hot tubs and some indoor pools, and biguanide-based sanitizers (sold under brand names like Baquacil) represent a smaller but significant market share. Each presents distinct challenges for emergency drinking.
Bromine is chemically similar to chlorine but produces its own set of disinfection byproducts, including brominated THMs, which some research suggests may be more toxic than their chlorinated counterparts. The good news is that bromine, like chlorine, is volatile and can be reduced through off-gassing and boiling. The bad news is that brominated DBPs tend to be more stable, so carbon filtration becomes more important.
Biguanide-treated pools are a trickier case. Polyhexamethylene biguanide (PHMB) is a synthetic polymer that acts as a bactericide. It does not break down easily with boiling or sunlight, and it is not well-removed by basic carbon filtration. If you are in a genuine survival situation and the only water available is from a biguanide-treated pool, distillation is your best option. The compound has a much higher boiling point than water, so steam collection will leave it behind.
Copper and Other Metals
Many pools use copper-based algaecides, and some mineral sanitizer systems introduce both copper and silver ions into the water. Copper at low levels (below about 1.3 ppm) is not harmful for short-term consumption, though it can give water a metallic taste. Pools that have been heavily treated with copper algaecides, especially if they have had recurring algae problems, can accumulate copper well above that threshold.
Research on copper-based algaecides shows that when these products kill algae, the dying cells can release their contents into the water, including potentially harmful compounds like microcystin-LR from cyanobacteria.
If the pool water has a blue-green tint that is not from the pool’s liner or paint, be cautious. That color often indicates elevated copper or a cyanobacterial bloom, and in either case the water needs more treatment than simple boiling. Carbon filtration helps with some dissolved metals, and distillation removes them almost entirely.
A Practical Step-by-Step for a Real Emergency
Here is a realistic sequence using supplies you might actually have on hand during a disaster:
- Collect from depth: Draw water from below the surface but above the drain. Surface water collects floating debris and sunscreen oils; bottom water accumulates settled sediment.
- Pre-filter: Pour through a clean cloth, coffee filter, or layered t-shirt to remove visible particles, leaves, and insects.
- Let it sit: If the water smells strongly of chlorine, leave it in an open container in sunlight for several hours, stirring occasionally. This allows free chlorine to off-gas.
- Boil if possible: A rolling boil for one minute kills pathogens including chlorine-resistant Cryptosporidium, and drives off remaining free chlorine and some volatile DBPs.
- Carbon filter if available: Run cooled water through a household pitcher filter or any activated carbon filter you have. Even a fish tank filter cartridge works. This reduces remaining chloramines, some THMs, and improves taste.
- Drink in moderation: Even after treatment, this water is not equivalent to municipal tap water. Drink what you need to stay hydrated but do not use it as your primary water source any longer than necessary.
How Much Is Safe to Drink
There is no hard safety limit published specifically for drinking treated pool water, because no regulatory body anticipates people doing it routinely. But we can work from what we know about the individual components.
For chlorine itself, the World Health Organization’s guideline for chlorine in drinking water is 5 mg/L (5 ppm), which is actually above the typical pool range of 1 to 3 ppm. So the chlorine alone, at normal pool levels, is within a range your body can handle in the short term. The problem is everything else in the water alongside it.
For DBPs, drinking water regulations in most countries cap THMs at 80 parts per billion (ppb) and HAAs at 60 ppb. Pool water frequently exceeds both of those limits. But those regulatory limits are set for lifetime daily consumption. Drinking pool water for a few days during an emergency is a very different risk profile than drinking it for 30 years. Short-term exposure to elevated DBPs is unlikely to cause acute illness, though it may cause gastrointestinal discomfort.
A reasonable approach in an emergency is to limit consumption to what you need to prevent dehydration, roughly two to three liters per day in moderate conditions, and to switch to a better water source as soon as one becomes available. If you are rationing, pool water treated with the steps above is safe enough for short-term survival use.
Taste and Whether It Matters
Pool water tastes bad. That chemical-swimming-pool flavor comes primarily from chloramines (formed when chlorine reacts with nitrogen compounds from sweat and urine), plus the metallic or astringent notes from dissolved minerals and treatment chemicals. Even after treatment, the taste will not resemble tap water.
Research on chlorine taste perception in drinking water found that people begin detecting chlorine at surprisingly low concentrations, with median detection thresholds around 0.5 to 1.7 mg/L depending on the baseline water quality. Rejection thresholds, where people found the taste unacceptable, ranged from about 1.6 to 2.2 mg/L.
In an emergency, taste matters less than hydration. But if the taste is bad enough that someone (especially a child) refuses to drink the water, it becomes a practical problem. Letting chlorine off-gas, running water through a carbon filter, and adding a small amount of flavoring like powdered drink mix can all help. Even a squeeze of lemon juice improves palatability, and the citric acid has a mild dechlorinating effect as a bonus.
Hot Tubs Are a Worse Starting Point
If the pool is unavailable and only a hot tub is on hand, be aware that hot tub water presents a harder challenge. The warm temperature promotes microbial growth, including Legionella and Pseudomonas. Hot tubs use higher concentrations of bromine or chlorine to compensate, which means more DBPs. The water volume is much smaller, so contaminant concentrations from bather inputs are proportionally much higher. And many hot tubs use additional chemicals like defoamers, pH adjusters, and enzyme-based clarifiers that add to the chemical load.
If a hot tub is your only option, treat it more aggressively: boiling is non-negotiable, carbon filtration is strongly recommended, and distillation is the ideal if you can rig it. Limit intake to what you absolutely need to avoid dehydration, and recognize that this water, even after treatment, carries more risk than pool water treated the same way.
When the Pool Has Gone Green
An unmaintained pool during an extended emergency can turn into a murky green swamp within days, especially in warm weather. The green color usually indicates an algal bloom, sometimes accompanied by bacterial overgrowth. This water is still usable, but it needs more aggressive treatment.
Start by filtering out as much of the algae as possible. Layered cloth filtration will catch the bulk of it. If you have any kind of flocculant (even a pinch of alum, which is sometimes found in spice racks as pickling alum), you can add it to the water and let it sit for an hour. The alum causes suspended particles to clump and settle, leaving clearer water on top that you can carefully pour off.
After clarifying, the water still needs disinfection. Boiling is again the most reliable method. If the bloom includes blue-green algae (cyanobacteria), be aware that the toxins they produce, including microcystins, are not destroyed by boiling. Activated carbon filtration is your best field-expedient option for reducing microcystin levels. If you have no carbon filter and suspect cyanobacteria (the water has a distinct musty or earthy smell and the “algae” looks more like spilled paint than grass clippings), this water should be a last resort.