Water is one of the most essential things we need to survive. We use it for drinking, cooking, bathing, and more. But if water sits for too long, it can become unsafe to consume. So how long is too long for water to sit before it goes bad?
Can water go bad?
Yes, water can spoil after a period of time. The main reasons water can go bad are:
- Bacterial growth – Bacteria and other microorganisms can multiply in stagnant water over time, causing the water to become contaminated.
- Chemical changes – As water sits, chemicals like chlorine and fluoride added during water treatment can dissipate, making the water less safe.
- Environmental pollution – Standing water can absorb pollutants and toxins from pesticides, industrial waste, and other contaminants that make it unsafe.
Stagnant water provides an ideal environment for bacterial growth. Many types of dangerous bacteria can thrive in sitting water over time, including E. coli, Legionella, and Salmonella. Microbial growth is the primary safety concern with stored water.
Factors that affect how long water remains fresh
There are several key factors that impact how long water will stay safe to drink before spoiling:
- Container cleanliness – Dirty containers can introduce bacteria. Storing water in a thoroughly cleaned and sanitized container is best.
- Container material – Porous materials like clay can allow microbes to enter over time. Non-porous plastics, metals, and glass are better.
- Sunlight exposure – UV rays from sunlight can kill bacteria. Storing water in opaque containers blocks this disinfecting effect.
- Temperature – Warmer temperatures speed up bacterial growth. Cool and dark storage areas are ideal.
- Source of water – Clean, potable water from municipal supplies lasts longer than untreated water from lakes, etc.
- Preservatives added – Disinfectants like chlorine help prevent microbial growth and keep water fresher for longer.
Following proper sanitation and storage methods can extend how long water stays safe to drink before it goes bad from bacteria accumulation.
How long does water last in storage?
With ideal storage conditions, here are general guidelines for how long drinking water can be kept before spoiling:
| Storage Vessel | Time Water Stays Fresh |
|---|---|
| Clean, sealed plastic bottle | 6 months to 1 year |
| Clean, disinfected plastic bucket or barrel | 6-12 months |
| Properly maintained water tank/cistern | 6-12 months |
| Municipal water pipes | 3-5 days stagnant |
| Old water pipes/plumbing | 1-2 days stagnant |
Note that these times are general guidelines only. Many factors can affect how long stored water remains fresh and potable.
Bottled water
Commercially bottled waters sold in sealed plastic bottles also have shelf lives. The FDA regulates bottled water and requires an expiration date of up to 2 years:
- Non-carbonated bottled water – 2 years from bottling date
- Carbonated bottled water – 1 year from bottling date
The plastic used for disposable water bottles typically has a 2 year safe shelf life before leaching chemicals. So bottled waters generally stay fresh tasting for:
- 6-9 months – Non-carbonated
- 3-6 months – Carbonated
Note that expiration dates are for optimum quality, not safety. Bottled water may remain safe to drink for longer than the expiration date if properly stored.
Tap water
Tap water has additives like chlorine that help keep it potable for 3-5 days in clean pipes. In older plumbing, tap water may start tasting stale within 1-2 days but still be safe to drink. Flushing stagnant tap water through for a few minutes can freshen the supply.
Natural water sources
Untreated water from natural sources like lakes, rivers, springs, etc. can spoil and become unsafe to drink much more quickly than municipal tap water supplies. It may contain harmful bacteria from animal/human contamination:
- Rivers/streams – Safe up to 1-2 days
- Freshwater lakes – Safe up to 3-4 days
- Springs – Safe up to 1 week if protected
Without disinfection, natural water sources should not be stored long term for drinking. Proper treatment methods like boiling, filtration, or chemical disinfectants are needed to store natural water for longer durations.
How to tell if water has gone bad
Signs that indicate water may have spoiled and become unsafe to drink include:
- Cloudy appearance – Cloudiness indicates microbial growth or sediment
- Bad odor – Stale, musty, or rotten smells signal contaminants
- Change in taste – Sour, metallic, or sharp tastes often mean spoilage
- Color changes – Pink, yellow, green, or black discoloration
- Particles floating – Bits of organic matter or biofilm
- Algae or mold – Visible growth inside storage container
If stored water exhibits any of these warning signs, it is best not to drink it. Odors, flavors, clouds, and colors can mean dangerous levels of bacteria are present. When in doubt, it is safer to discard questionable water.
Water testing
To be completely sure if stored water is still potable, laboratories can test it for:
- Microbial contaminants – Presence of harmful bacteria like coliform, E. coli, Salmonella, etc.
- Chemical toxins – Unsafe levels of heavy metals, pesticides, industrial waste, and other pollutants.
- Nitrates/nitrites – Levels exceeding safe drinking standards.
- Total dissolved solids (TDS) – Mineral salts and particles above recommended concentrations.
Home water test kits are also available to check for common contaminants. Testing can confirm if stored water has spoiled and should be discarded.
Improving water freshness in storage
Proper storage and disinfection techniques can extend how long drinking water stays fresh before going bad. Recommendations include:
- Use food-grade plastic, glass, or enamel-lined metal containers
- Clean containers thoroughly before filling
- Sanitize with bleach, UV light, or hot water before use
- Replace old containers that may be scratched or leaching chemicals
- Fill containers fully to minimize airspace
- Store in cool basement or cellar area if possible
- Keep containers in dark storage without sunlight exposure
- Use oxygen absorbers in storage container
- Rotate stored water supplies every 6-12 months
- Add stabilizing chemicals like chlorine if storing for long durations
- Consider filtration and Reverse Osmosis pretreatment if source water may be contaminated
Taking appropriate precautions when storing drinking water supplies can help extend freshness and prevent bacterial growth issues.
Water preservatives
Chemical disinfectants and preservatives allow stored water to stay fresher longer by killing microbes. Common options include:
Chlorine bleach
Adding small amounts of ordinary chlorine bleach helps sanitize drinking water for storage. Typically 1/8 teaspoon (~0.75ml) per gallon (3.8L) is sufficient. Sodium hypochlorite bleach solutions should contain 5–8% available chlorine concentration.
Chlorine dioxide
Chlorine dioxide water tablets or drops release precise low doses of chlorine over time. They are often used for camping water but work for stored reserves too.
Iodine
Liquid 2% tincture of iodine or iodine tablets provide disinfection for stored drinking water. Approximately 5 drops or one crushed tablet per quart are added.
Hydrogen peroxide
A 3% hydrogen peroxide solution is another option for water preservation. About 8 drops (0.5 ml) per quart help prevent bacterial growth during storage.
Silver ions
Colloidal silver or silver-impregnated ceramic filters release silver ions that inhibit microbial growth in stored water.
Vodka or grain alcohol
A 50% distilled spirits alcohol solution makes a reasonable emergency water disinfectant. About 1 ounce per quart of water is effective.
Water container maintenance
Properly cleaning and maintaining water storage containers is also important. Recommendations include:
- Wash with soap and hot water before each use
- Rinse thoroughly with clean water
- Air dry fully upside down with no lid before filling
- Sanitize monthly with bleach or other disinfectant
- Replace worn containers that leak or have cracks
- Use only containers made for water storage
- Clean spigots/taps regularly
Well-maintained storage containers minimize bacterial ingress and preserve water quality.
Frequently Asked Questions
Does water expire or go bad?
Water itself does not expire, but it can become contaminated and unsafe to drink after a period of time. Stagnant water can breed dangerous microbial growth in as little as a few days or weeks.
What makes stored water go bad?
The main spoilage factors are microbial contamination, chemical changes, and environmental pollution. Bacteria are the primary concern in terms of safety and water freshness.
Can old plastic or rusty containers taint water?
Yes, over time plastic bottles and old containers can leach chemicals into the water, causing an unpleasant taste and potential health risks. Rust particles can also contaminate stored water supplies.
Does freezing extend how long water stays fresh?
Freezing stops most microbial growth in stored water. However, freezing does not necessarily kill all bacteria and viruses. Containers may crack or leak when water expands during freezing as well.
Can stagnant tap water make you sick?
After around 3-5 days, undrinkable tap water may harbor dangerous bacterial contamination if left sitting. Consuming such water could potentially cause illness.
Is cloudy water safe to drink?
No, cloudiness usually signals the presence of microbes or sediment in water that make it unsafe for drinking. Heavily clouded water should be filtered, treated, or discarded.
Conclusion
Water that is properly stored and maintained can remain fresh and potable for 6-12 months typically before bacterial contamination becomes a health risk. Bottled water lasts around 6 months to 2 years before tasting stale. Tap water can go bad in as little as 1-2 days stagnant in old pipes but municipal supplies stay safe for 3-5 days in clean plumbing. Disinfecting stored water supplies with chlorine or other preservatives helps extend the shelf life. But if you notice any changes in taste, smell or appearance, it is safest to discard questionable water rather than taking risks.
