How long can water be stored?

By Bob Fear

How long can water be stored?

Does water expire? How long does it take for a glass of water to go bad? How long does bottled water last? Yes - water can go bad, but how long this takes depends on how your water’s been treated and how it’s been stored. We take a look at all the conditions that determine how long drinking water can be stored.

How long can tap water be stored?

Tap water that’s been treated with chlorine to disinfect it can be stored in the fridge for around 24 hours and still be safe to drink, according to Water UK - the organisation representing water and wastewater service providers. It’s best stored in a sealed glass bottle to prevent any contamination. After 24 hours, it’s likely that the chlorine will have evaporated and bacteria may begin to grow, although this depends on the amount of water, the temperature it’s stored at, and the amount of chlorine in it.

Water should be stored in sealed containers as it’s a universal solvent, meaning it dissolves more substances than any other liquid and ‘it takes odours and it takes flavours’ according to US water sommelier Martin Reiss. Leaving an open glass of water near anything that smells means that it’s likely to become contaminated. This is why it’s not advised to store water next to cleaning products and chemicals, especially if they’re in permeable plastic bottles.

It’s best to store water in glass containers as this won’t affect the water at all. Stainless steel is a good alternative as it’s non-corrosive and doesn’t leach chemicals. Plastic is slightly permeable and can contaminate the water with the potentially harmful chemical BPA over time. Aluminium bottles lined with an epoxy resin commonly used in food and beverage cans have also shown to leach BPA into water.

How long can you leave a glass of water out?

Carbon dioxide dissolves in water and alters its PH level so it becomes slightly more acidic. This will change the taste of your drinking water, as will any likely bacterial growth or changes in the mineral content over time. Bacteria will grow more in warm water, especially if any chlorine has evaporated. Therefore it’s best to discard any warm water that’s been left open for more than 12 hours.

To help prevent your glass of water tasting stale or smelling off, simply keep it covered. This is especially handy if you leave a glass of water by your bedside overnight to drink first thing in the morning.

How long can bottled water be stored?

While manufacturers of bottled water have to employ strict bottling methods to make sure their products last while on the shelves, water in plastic bottles should come with an expiry date. This expiry date, usually one to two years after manufacture, relates to the plastic packaging. Plastic begins to release chemicals into water after time, and these will slowly accumulate in our bodies if we regularly drink water from plastic bottles.

As bought bottled mineral or spring water shouldn’t contain any chlorine, once opened, bacteria will begin to grow. Bacteria growth will be far less if the water is refrigerated. But as plastic is permeable, it’s best to store any drinking water in sealed glass containers.

Shop bought bottled water, once opened, is best drunk within a few hours - especially if it’s being kept at room temperature.

How long can filtered water be stored?

Potentially, filtered water could be stored for a few weeks, as long as it’s refrigerated and kept sealed in a glass bottle. If kept at room temperature, then filtered water is best drunk within a few hours. If you’re taking your filtered water out and about, it’s best kept in a tightly sealed stainless steel flask that’ll help keep it cool as long as possible. As your stored filtered water shouldn’t contain any chlorine, then bacteria will begin to grow - especially if exposed to sunlight or kept at a warm temperature.

To enjoy it at its best, filtered water is always best drunk as soon as possible. A decent home filtration system will ensure you always have freshly filtered water on tap. The Virgin Pure countertop water system filters your tap water directly from your mains supply, removes the chlorine and many other contaminants, and then keeps the bacteria at bay with ultraviolet light treatment. Virgin Pure’s inbuilt heating and refrigeration systems means that it can dispense your filtered water at fifty different temperatures, from boiling to chilled, at the touch of a button. Therefore you’ll no longer need to store drinking water at all.

Do you want to find out more about the various types of water available? Discover them all, from mineral to distilled and purified water.

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