The length of time water can be stored depends on the container, its condition, and the storage environment. To keep your water safe and fresh, use a food-safe container that’s been thoroughly cleaned before use. Once filled, seal the container tightly and store it in a cool, dark place, like a fridge or pantry, to help prevent bacteria growth and exposure to contamination. How long the water should be stored also depends on the type of water:
Sealed tap water
Tap water sealed in an air-tight bottle or container can remain safe to drink for up to 6 months if stored properly. However, the type of container and how well it’s sealed play a significant role in preserving the water, so this timing can differ greatly. For example, when exposed to sunlight or heat, plastic bottles can degrade, potentially releasing harmful chemicals like BPA into the water, which could pose health risks. Additionally, if the container hasn’t been properly cleaned or sealed, this risks exposure to bacteria or contamination, making the water unsafe to drink much sooner.
Read more about the safety of tap water in the UK.
Unsealed tap water
Tap water left out in a glass or cup has a much shorter shelf life compared to water that’s properly sealed. This is due to the increased risk of contamination. Experts suggest that open tap water shouldn’t be left for more than 24 hours. Over time, gases like carbon dioxide can enter unsealed water, altering its pH and making it taste stale. Additionally, chlorine, used to treat drinking water, can evaporate when exposed to air, creating an environment where bacteria can thrive.
Discover more in our article about the importance of water pH.
Bottled water
Bottled water is sealed to keep bacteria out and maintain its freshness. However, bottles made from materials like Polyethylene Terephthalate (PET) are slightly permeable, which means that gases can seep into the water over time, potentially altering the taste and smell. Additionally, the plastic itself can degrade, releasing chemicals that may affect the water’s quality. Because of this, plastic water bottles often come with a ‘best before’ date, giving a helpful guideline for when the water is at its best in terms of taste and freshness. As long as the seal remains intact, the water is safe to drink. But once opened, it’s important to follow the same precautions as with tap water and consume it within 24 hours.
Filtered water
Filtered water can be safely stored in the fridge for 3-5 days, as long as it’s kept in a clean, sealed container. This makes it a more sustainable way to store water while keeping it fresh. Filtering also helps remove any unwanted tastes or odours that can develop over time.