How long can you keep tap water? Up to 7 days

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How long can you keep tap water? Times per situation

There's no single figure that's right for every situation. Storage time depends on three things: temperature, whether the bottle is clean and sealed, and whether you drink straight from it. Below are the times as given by the Dutch drinking water companies and Voedingscentrum.

Voedingscentrum recommends 3 to 7 days in the fridge for opened water, 3 days in the kitchen cupboard and up to 1 year in the freezer. That's the broadest and most useful guideline for everyday use.

Why the answers vary so much

If you google this question, you'll get three different figures within the first five results. That's not sloppiness on the part of the sources, but a difference in starting point: one water company works from the safe lower limit, another from the maximum period under ideal conditions. Here they are side by side.

Practical translation: count on 3 days if you want to play it safe, and a maximum of a week if the bottle is genuinely clean and sealed and you don't drink from it. According to Waterbedrijf Groningen, the most honest remark here is that you don't really need to store tap water at all, because it always comes straight from the tap. That's true, until you put together an emergency kit or take your water bottle to work.

Why tap water doesn't keep indefinitely

Dutch tap water comes out of the tap virtually chlorine-free. That's pleasant for the taste, but it also means there's no residual disinfectant in the water to stop bacterial growth, unlike in many other countries. So once the water is out of the pipe, it's left unprotected.

What happens in that bottle

Three processes run side by side. First, bacteria grow that get into the water via your hands, your mouth or the air; above around 20 degrees, that happens a lot faster. Second, algae and yeasts develop if light gets in, which you'll see as flecks or a greenish haze. Third, the dissolved carbon dioxide disappears, which makes the water taste flat and lukewarm, even if it's still fine microbiologically.

How dangerous is old tap water?

Less than many people fear. Water that's been left standing a few days too long mostly starts to taste and smell unpleasant, and you'll notice that before it becomes a problem. Concern around legionella is usually misplaced too: the RIVM states that people don't get ill from drinking contaminated water, because the bacterium enters through inhaled mist, for example in the shower. One thing does apply: if you've been on holiday for two weeks, run the taps for a bit. According to the RIVM, that's good for refreshing the drinking water in your pipes.

One thing that is worth watching is the temperature of the water you draw. We looked separately into why you're better off not drinking warm tap water: in the hot water pipe and boiler, the chance of bacterial growth and of metals leaching in is greater. So always draw cold water if you're going to store something.

The best way to store tap water

The rules are simple, and they make a factor of two to three difference in storage time.

• Draw it cold: let the tap run for a moment until the water actually feels cold, so you get fresh water from the main pipe instead of water that's been sitting in your own pipe.
• Choose glass or stainless steel: these materials barely leach any substances and are easier to get properly clean than a plastic bottle with a sports cap.
• Fill to the brim: the less air in the bottle, the less room for bacterial growth. This is exactly what Vitens lists as the fourth step in its step-by-step plan.
• Put the cap or lid on: an open jug in the fridge picks up odours from cheese, onion and leftovers.
• Keep it cold and dark: the fridge for daily use, a pantry or cellar for a stock.
• Wash the bottle daily: warm water and washing-up liquid, or simply in the dishwasher. Don't forget the cap, since that's where most build-up collects.

At PureFilter, we see that this is exactly where customers drop off: keeping up with one carafe works fine, but washing and filling three bottles every day doesn't. That's also why jugs and carafes at home often end up back in the cupboard after a few weeks.

Storing tap water for your emergency kit

A completely different period applies to an emergency supply, and that's the main reason the answers to this question vary so much. Both Brabant Water and Vitens advise refreshing self-stored tap water every 6 months, provided it's kept in clean, well-sealed bottles or jerrycans filled to the brim, in a cool, dark place, dated.

On the quantity, the water companies do agree. The government advises a three-day supply, which works out at a minimum of 3 litres per person per day: 2 litres for drinking and 1 litre for preparing food. For a family of four, that's 36 litres. Allow roughly half a litre per pet per day extra. If you want to know how that compares with your usual usage, take a look at how much water you need per day.

To put that in perspective: according to Brabant Water, drinking water companies can keep supplying water themselves for 10 days during a power outage, and if there's an interruption of more than 24 hours you'll get emergency drinking water at 3 litres per person per day. Boil that water for 3 minutes to be safe if you're not sure your own jerrycan was clean.

How to tell the water has gone off

You don't need to do the maths: your eyes and nose do the work. Voedingscentrum names two clear signals: the water is no longer clear, or there are black specks in it. In practice, a few more can be added to that.

• Flecks or strands: visible particles that move when you tilt the bottle.
• A green or brown haze: algae growth, almost always caused by light and warmth.
• A slimy layer on the inside: a biofilm, usually in the cap or around the sports spout.
• A musty or earthy smell: if it smells off, it is off.
• A flat, lukewarm taste: not a health problem, but the reason a day-old carafe tastes less good.

Not sure? Look first, then smell, then take a small sip. If you don't trust it, don't pour the water away, give it to your plants instead. Visible brown or grey particles that come straight out of the tap are a different matter: that's usually iron or manganese from the pipe network, and you tackle that at the source, for example by filtering limescale out of your tap water or having the pipe flushed.

What filtering changes about storage time

There's a misconception here that we want to be honest about: filtering doesn't make water keep any longer. A carbon filter removes substances but doesn't add a preservative. Filtered water in a bottle therefore has the same storage time of roughly 3 to 7 days chilled. With a filter jug it can even be shorter, because the water in the reservoir stands still and the filter cartridge itself is a place where bacteria can settle if you leave it too long.

What a fixed filter does change is that you no longer need to store anything. An under-sink system filters at the moment you turn on the tap, so every glass is fresh by definition. No jug in the fridge, no bottles to fill, no caps to scrub. That's exactly why an inline filter is easier to stick with in practice than a jug.

The PureFilter Mineral+ is a five-stage under-sink filter that removes more than 100 contaminants, including PFAS, microplastics, heavy metals such as lead and copper, nitrates, pharmaceutical residues and chlorine, to around 99 per cent. After that, the Swedish Mineral Rock™ adds magnesium, calcium and potassium back in, so the water doesn't taste flat. The system is certified to NSF 42, 53, 61 and 372, and you install it in 5 to 10 minutes without a plumber or tools; see how to install a water filter for the steps. If you'd first like to understand how the different types of water filter compare to each other, that's the best place to start.

Storing, jugs or a fixed filter side by side

Three ways to get a glass of cold, nice-tasting water, with the actual effort involved.

The honest conclusion: if you just want cold water, a carafe in the fridge is free and fine. If you also want to get something out of your water, the question isn't whether you store it but how you filter it. Take a look at water filters for the home for that, and for the maths behind the cost per litre, we've worked out what a cubic metre of water costs.

Buying advice: when to store, when to filter

Keep storing it if it's for an emergency supply

For an emergency kit there's no alternative: bottles or jerrycans, 3 litres per person per day, refreshed every 6 months. A filter doesn't help there, because it needs water pressure.

Keep storing it if you just want cold water

If you like tap water but find it too lukewarm, a glass carafe with a lid in the fridge is the cheapest solution there is. Top it up every two to three days and wash it out weekly.

Choose a fixed filter if you can't keep up with the maintenance

If you're filling multiple bottles a day for a family, or there are consistently three jugs in the fridge and you don't know how old they are, an under-sink filter solves the underlying problem: you no longer have to plan ahead.

Choose a fixed filter if you also want to get something out of your water

If your concern isn't bacteria but PFAS, microplastics, pharmaceutical residues or lead from old pipes, storing changes nothing about that. Only filtration does. A certified multi-stage system costs €149.00 including the first filter, with 40 days free returns and a 5-year guarantee.

Frequently asked questions

Conclusion

How long can you keep tap water? In a clean, sealed bottle in the fridge, 3 to 7 days; outside the fridge, 1 to 2 days; in a drinking bottle you drink from, one day; and as an emergency supply, 6 months. The differences between sources don't come from disagreement, but from a different starting point: 2 to 3 days is the safe lower limit, a week the maximum period under ideal conditions.

The underlying reason is always the same. Dutch tap water is excellent, but it contains almost no chlorine, so once it's drawn, nothing is left to stop bacterial growth. Everything that extends storage time is therefore about hygiene and temperature, not about the water itself. And filtering doesn't change that period: it simply makes storing unnecessary, because you draw filtered water the moment you need it. Anyone who also wants to remove PFAS, microplastics, heavy metals or pharmaceutical residues from their water while keeping the minerals ends up with a certified under-sink system for less than one cent per litre.