Water is essential for life. We need it to stay hydrated and for our bodies to function properly. But can you drink water that’s been sitting around for over 24 hours? Is day old water safe to consume or should you always drink fresh water?
What happens when water sits out?
When water sits stagnant, exposed to air, for an extended period of time, chemical and microbial changes can occur:
- The chlorine used to disinfect tap water can dissipate over time. This allows bacteria to start growing in the water.
- Dust and particles in the air can contaminate the water, introducing microbes.
- Chemicals like lead and copper from pipes can leach into stagnant water.
- Bacteria like pseudomonas and E. coli can multiply in the water.
The longer water sits, the higher the risk of contamination. At around the 24 hour mark, there is potential for bacterial growth that could make the water unsafe to drink.
Is it safe to drink day old water?
In general, it’s best to avoid drinking water that has been sitting out for over 24 hours. The risks tend to outweigh the benefits. Here are some factors to consider when deciding if day old water is safe to drink:
The source of the water
Tap water that has been sitting at room temperature for over 24 hours is more likely to harbor bacteria growth and chemical leaching. If you store a pitcher of tap water in the fridge for a day, it’s generally safer than water left out on the counter. Refrigeration slows bacterial growth.
Bottled water can typically last longer before going bad, about 6 months past the expiration date, if properly sealed. The plastic bottles help prevent chemical leaching and contamination.
Visible signs of contamination
If the day old water is cloudy, foamy, or smells odd, that’s a sign microbes are growing in it and it’s best not consumed. Safe drinking water should be clear and odorless.
Your immune health
People with compromised immune systems, like the elderly, pregnant women, infants, and those undergoing cancer treatment, are at higher risk for getting sick from contaminated water. It’s advisable to avoid drinking any water that’s sat out for over 24 hours.
For those with healthy immune systems, drinking a glass of day old water left in a sealed bottle or jug in the fridge is generally low risk. But it’s still advisable to dump it and start with a fresh supply.
Purpose of the water
In some cases, day old water may be fine for uses other than drinking. For cooking, boiling the water first will kill any harmful bacteria in day old water. For household cleaning, the microbial risks are minimized since the water isn’t being ingested.
However, it’s best to avoid using day old tap water for brushing teeth, since it can introduce bacteria into the mouth.
How to store water properly
To help maximize freshness and minimize health risks, here are some tips for proper water storage:
- Use clean, sealed containers – don’t store in open containers that allow air exposure.
- Replace pitcher filters as recommended to optimize water quality.
- Keep water in the fridge instead of at room temperature.
- If storing in plastic bottles, don’t let them sit in sunlight or heat which can increase chemical leaching.
- Rinse containers thoroughly before refilling to remove bacteria buildup.
- If water has an off taste or smell, it’s safest to discard it.
How long does water last in the fridge?
Clean tap water properly stored in a sealed container in the refrigerator should last about 5-7 days before needing to be refreshed. The cool temperature slows bacterial growth. Beyond a week in the fridge, it’s best to discard and replace stored water.
How long does bottled water last?
Unopened commercially bottled water typically lasts:
| Container | Shelf Life |
|---|---|
| Plastic Bottle | 18 months – 2 years |
| Glass Bottle | Indefinite |
| Boxed/Cartoned | 9-12 months |
Once opened, bottled water should be used within:
- Plastic bottles: 5-7 days
- Glass bottles: Indefinite but best consumed within a month
- Boxed: 3-5 days
Note these timelines assume proper storage at room temperature or in the fridge. The countdown starts when the seal is broken. Leaving containers in hot cars or direct sunlight can shorten shelf life.
How to freshen stale water
If you have water that’s approaching a day old and you’re wondering if it’s still safe, there are a few tricks to freshen it up:
- Boiling: Bringing water to a rolling boil for 1 minute kills most bacteria, viruses, and parasites that can make water unsafe. This won’t remove chemical contaminants.
- Freezing: Freezing water for around 3 hours solidifies any microbial contaminants so they can be separated from ice. But this doesn’t remove chemicals.
- Adding lemon: Lemon juice can help kill some bacteria and improve stale taste. But it doesn’t make water safer to drink.
- Filtering: Pouring water through an NSF-certified water filter can remove some contaminants and improve taste/smell.
Can old water make you sick?
Drinking contaminated day old water can cause illness. Here are some common waterborne infections:
E. coli infection
Raw sewage often contaminates water and can introduce Escherichia coli bacteria. Symptoms include severe stomach cramps, diarrhea, vomiting, and fever.
Legionnaires’ disease
Legionella bacteria thrive in warm water environments like hot tubs, plumbing systems, and hot water tanks. Inhalation causes cough, muscle aches, fever, and more severe lung infections like pneumonia.
Hepatitis A
Hepatitis A virus is transmitted through food or water contaminated by infected feces. It causes liver infection with symptoms like fever, nausea, stomach pain, dark urine, and jaundice.
Giardiasis
This intestinal illness is caused by a parasite in contaminated water. Symptoms include diarrhea, gas, greasy stools, dehydration, stomach cramps, and nausea.
People with compromised immune systems are most at risk when drinking bad water. But even healthy people can experience acute symptoms if significant quantities of pathogens are ingested.
Does hot or cold temperature affect water safety?
Water temperature does impact drinking safety:
- Hot temperatures allow bacteria to multiply faster – Keeping water sealed and refrigerated is best for minimizing bacterial growth. Water from the hot tap can harbor more bacteria.
- Freezing water kills germs – Freezing is an effective disinfection method. As water freezes, ice crystals rupture cell walls of bacteria. Thawing will release the dead microbes which can be filtered out.
- Boiling water kills germs – Bringing water to a rolling boil for 1 minute kills most disease-causing microorganisms by denaturing their proteins.
The safest drinking water is from a securely sealed container kept refrigerated. Heating water to a boil or freeze can also kill germs, but won’t remove chemical contaminants.
Does water go bad or expire?
Water itself does not expire or go bad. But over time, stored water loses freshness and can become contaminated:
- Bottled water carries expiration dates for the plastic container, not the water itself. After the expiration date, chemical leaching increases but water doesn’t suddenly become harmful.
- The chlorine in tap water dissipates over time, reducing disinfection ability and allowing bacterial growth after 24 hours.
- Left undisturbed, tap water can leach metals like lead and copper from pipes after about 6 hours.
So while water won’t ever “go bad” in the traditional sense, we consider it “expired” when an unacceptable level of contamination occurs.
How to tell if water has expired
Signs that water may be past its prime and require replacing include:
- Appearance: Cloudiness, foam, sediment
- Smell: Chlorine or musty odor
- Taste: Metallic, bitter, or stale
- Container: Old bottle or jug past expiration date
If water exhibits odd tastes, smells or appearances – it’s safest to discard it and start fresh.
Conclusion
Drinking water that’s been sitting out for over 24 hours does carry an increased risk of bacterial contamination. For vulnerable populations, it’s best to avoid day old water as a precaution. Healthy adults can likely manage the low risk, but there is no concrete shelf life for how long water “lasts.”
The key is minimizing contamination. Keeping water sealed, refrigerated, and discarding after 5-7 days provides the best insurance of freshness. If in doubt, start with a new batch rather than trying to revive stale water. With proper storage and handling, drinking water can stay pleasantly potable for about a week before needing to be replaced.