Storing and treating drinking water

A person can survive for perhaps three weeks without food, but only about four days without fluids. That is why water comes first in your supplies – and why it pays to know a few simple steps before the water ever stops or becomes contaminated.

At a glance

• 2 litres per person per day: 1.5 litres for drinking, 0.5 litres for cooking. For ten days that is 20 litres per person – but even a three-day supply helps a lot.
• Bottled water is the easiest supply: store it somewhere cool and dark, use it up by the best-before date and buy more.
• For washing and the toilet you need extra non-drinking water on top – it does not have to be drinking water (bath, buckets, containers).
• Boil-water notice: bring water to a rolling boil once and let it cool for at least 10 minutes – also for brushing teeth, baby formula, ice cubes and washing fruit and vegetables.
• Floodwater, fuel, chemicals: such water cannot be made drinkable by boiling, filters or tablets. Use only your stored or bottled water.

Start small

You don't have to carry 20 litres per person into the cellar today. Every day of supplies counts, and three days is a good first step. Pick one of these small tasks each day – none takes longer than ten minutes, and most cost nothing:

• One extra pack of water with your next shop, put it in the cellar, storeroom or a cupboard. Best add it to your shopping list straight away.
• Write the date on it: write the best-before date in big letters on the pack with a thick marker – then you can see it without tearing the film open. You can enter it in your supplies and get a reminder.
• Find the main stop tap: where do you turn off the water in your flat or house? Go and look once, check that it turns, and note the location under Home.
• Set aside a large pot with a lid for boiling water – and think about how you would cook safely without electricity (see Power cut).
• Note down your water supplier: write the name, website and phone number of your local utility or water board on paper – they announce disruptions and boil-water notices.
• Set up warnings: install a warning app (for example NINA) and check whether there is a battery or wind-up radio in the house → Warnings.
• A filter or disinfection tablets: put them on your wish list and compare calmly what they can do – not in the middle of an emergency. Overview under Equipment.

Understanding

Tap water in Germany is very good and almost always available. That is exactly why people rarely think about what happens when it doesn't come. Knowing the reasons helps – then you also know which preparations help in which situation.

Why the water can fail

1. Power cut: waterworks need electricity and digital systems. If these fail, the water supply can fail too. According to the BBK, how quickly that happens depends on local conditions and on how high up you live – on upper floors the pressure may go sooner. In hard frost without heating, water pipes can also freeze and burst.
2. Damaged pipes: an accident, extreme weather or sabotage can damage the lines for electricity, water, gas or mobile networks.
3. Contamination in the network: if there are signs that germs – for example from faeces – have got into the drinking water, or if illnesses pile up, the local health authority considers a boil-water notice (Abkochgebot). It orders that tap water must be boiled before drinking.
4. Floods: floodwater often carries oil from flooded heating-oil tanks, contaminated sludge and faeces. Dirty water is a breeding ground for disease, and floods can also disrupt the water supply itself. Contamination can reach groundwater and private wells.

Drinking water and non-drinking water

Not all water in a household has to be of drinking quality. What matters is the order of priority when it runs short: drinking comes first, then cooking, then the bare essentials of hygiene – and only last flushing the toilet. For the toilet and cleaning, non-drinking water from the bath or a bucket is enough. The BBK explicitly calls drinking water "more important than food".

Who decides – and how you find out

• The local health authority (Gesundheitsamt) orders a boil-water notice and also lifts it. Only it may do so.
• The water supplier (local utility, water board) informs households, together with the local media. The notice usually says which area is affected and gives a phone number or website for questions.
• Warning channels: most information comes via warning apps and radio, plus loudspeaker vans and digital information boards, and in special situations sirens and mobile phone alerts. In a power cut or without a mobile network many of these channels don't work – but a battery, wind-up or car radio does. More under Warnings.
• Pass it on: the template notices of the German Environment Agency (UBA) explicitly ask you to tell housemates and neighbours, so the message reaches everyone.

Not every notice means the same thing. In its templates for consumer information, the UBA distinguishes several levels:

A boil-water notice is usually a bridge for a few days until disinfection, flushing of the network or another supply takes effect. For major emergencies, the federal government has also created more than 5,200 emergency drinking water wells and springs, mostly in residential areas of large cities; they are planned to supply 15 litres per person per day. Whether and how such water may be used is decided by the health authority. Your own supply is still the first help for the first few days.

Sources for this section: BBK guide (11/2025), BBK "Essen und Trinken bevorraten", BBK "Stromausfall" (2026), BBK "Empfehlungen bei Hochwasser" (2024), BBK "Wassersicherstellung", UBA recommendation on §§ 62–68 TrinkwV (2/2026), CDC "Reentering Your Flooded Home" (8/2026).

Preparing

How much water?

The BBK recommends being able to look after yourself for ten days if possible – but a supply for three days already helps a lot, and you can build on it step by step. Per person and day, the BBK ideally reckons with 2 litres: an adult needs at least 1.5 litres of fluid, plus 0.5 litres of water for cooking. Part of your supply should be (mineral) water; fruit juices and other drinks count too.

The supplies calculator works it out exactly for your household.

Plan for more in hot weather and during physical exertion, for pregnant women, for people who are ill and for pets. The 2 litres only cover drinking and cooking – water for washing and the toilet comes on top.

Bottled water: the easiest supply

For reasons of food hygiene, the Federal Office for Agriculture and Food (portal Ernährungsvorsorge) advises storing bottled water from the shop for your emergency supply – preferably in glass, otherwise in PET bottles. The reason: bottled water has a best-before date, so you know when to replace it.

• Shelf life: mineral water in its original sealed bottle keeps almost indefinitely in principle. Manufacturers usually give a best-before date of two years for glass bottles and one year for PET bottles. You can usually use unopened, well-stored bottles considerably longer.
• Where to store it: dark, cool, dry. Sun and heat reduce the quality.
• PET bottles are better suited to short- to medium-term storage: they can absorb odours from their surroundings and are slightly permeable to gases. In blazing sun or in a car, a substance from the plastic can also pass into the water and change its taste. So: not in the car, not by the window, not next to petrol or pesticides.
• Glass bottles are particularly suitable for longer storage, but heavy – handy for a cellar or ground floor.

Rotate instead of throwing away: the BBK recommends a simple cycle – build up a supply once, check the dates regularly (for example once a year on a fixed date), drink bottles that will soon expire in everyday life and replace what you use straight away. On the shelf that means: old at the front, new at the back. You push new packs to the back and drink from the front. A good fixed date is the nationwide warning day in September.

Filling tap water yourself

According to the Ernährungsvorsorge portal, there is no general statement about the shelf life, suitable containers and water quality of tap water you fill yourself – hence its recommendation for bottled water. If you still want to store tap water, for example because you can't carry much, follow these rules from the US Centers for Disease Control and Prevention (CDC):

1. Use food-grade containers meant for drinking water. Never containers that have held chemicals such as bleach or pesticides. Without a food-grade container: sturdy, unbreakable (not glass) and with a tight-fitting lid.
2. Clean it first: wash the container with washing-up liquid and sanitise it, then let it air-dry and fill it.
3. Label it: write "drinking water" and the date you filled it.
4. Store it properly: cool, out of the sun and away from toxic substances such as petrol or pesticides.
5. Replace every 6 months: pour out water you filled yourself (for example on the plants), clean the container, refill it, new date.

Empty, clean containers are handy anyway: for filling up when a cut-off is announced, and for holding non-drinking water.

Non-drinking water for the toilet and washing

Non-drinking water is water you don't drink – for flushing the toilet, cleaning and basic washing. In its checklist the BBK lists separate water containers for fire-fighting or non-drinking water. In an older edition of its guide (2018), the BBK recommends: if a longer disruption of the water supply is looming, fill every larger container available – bathtub, washbasins, buckets, pans, water containers – and remember the water for flushing the toilet.

You can make non-drinking water last longer with disinfection products; it's best to ask for advice in a camping or outdoor shop (BBK). To need less non-drinking water, a small hygiene supply helps: wet wipes and disinfecting wipes, dry shampoo or hand-cleaning paste, disposable crockery, kitchen roll, household gloves, bin bags and, if needed, a camping toilet with replacement fluid or bags. How to build an emergency toilet is explained in the guide Hygiene and emergency toilet.

Equipment for treating water

You don't need expensive gear. You probably already have the most important things:

• A large pot with a lid or a kettle – according to the UBA, a kettle is well suited to boiling water, but it needs electricity.
• Cooking without electricity: a gas hob often keeps working. A gas cooker may only be used indoors if it is approved for indoor use. Camping stoves with gas cartridges and gas or charcoal barbecues belong outdoors only – indoors there is a risk of life-threatening carbon monoxide poisoning. The BBK advises tested carbon monoxide alarms. More in the guide Power cut.
• Clean cloths or coffee filters for pre-filtering cloudy water.
• Clean containers with lids for boiled water.

A water filter or disinfection tablets can be an addition, for example if you cannot boil water. What matters is knowing what they do – and what they don't:

• Boiling kills all types of germs – bacteria, viruses and parasites. It is the best and simplest method (CDC, WHO).
• Portable filters do not remove viruses. To hold back bacteria, a filter needs an absolute pore size of 0.3 micron or smaller, for parasites 1 micron or smaller – this is stated on the pack. Only reverse osmosis filters also remove viruses. So after filtering you should also disinfect the water (CDC).
• Disinfection tablets: chlorine and iodine tablets kill most germs, but not the parasite Cryptosporidium. Chlorine dioxide tablets also work against it if you follow the instructions exactly. Dose and contact time are on the pack (CDC).
• Silver: products containing only silver are not a disinfectant for contaminated water. The WHO reviewed silver in 2018: it works only against some bacteria and needs long contact times; its effect against viruses and parasites is not proven. The WHO does not recommend silver as a disinfectant for drinking water. So check on the pack whether a product disinfects water or only keeps it fresh.
• Against chemicals, fuel and toxins none of these methods helps – neither boiling nor disinfecting nor filtering (CDC).

You'll find filters and tablets under Equipment; if you want some, add them to your shopping list.

Variations for your household

• Flat on an upper floor: here the water pressure may go sooner in a power cut. Keep your supply where you can reach it without a lift – bottles spread across cupboards or under the bed work too.
• House with a cellar: glass bottles and crates fit well in a cool, dark cellar – but not in one that floods during high water or heavy rain. Then better one floor up. See Floods.
• Your own well: if it is in a flood-prone area, have the water tested after flooding before you use it (CDC).
• With babies: for healthy infants, tap water can in principle be suitable for preparing food. It is boiled and cooled to about 30 to 40 °C; you should not use water filters for this, as they can be contaminated with germs. If the tap water is temporarily contaminated, still water labelled "suitable for preparing infant food" (Geeignet für die Zubereitung von Säuglingsnahrung) is an alternative (Verbraucherzentrale consumer advice centre). A few bottles of it belong in your supply. During water advisories the CDC also advises using ready-to-feed formula if possible.
• With pets: plan their water on top (BBK, CDC). How much depends on the animal – simply measure for a few days how much disappears from the bowl.
• With care needs or illness: people who are ill often need more water (CDC). For people with weakened immunity, further rules may apply during a boil-water notice – ask the treating doctor (UBA). Food and water for assistance animals belong in your supply (BBK).

Sources for this section: BBK guide (11/2025), BBK "Essen und Trinken bevorraten", BBK "Hygiene in Notsituationen", BBK guide English edition (12/2018), BLE Ernährungsvorsorge (FAQ; storing mineral water), Verbraucherzentrale Niedersachsen (9/2026), CDC (2024, 2025, 2026), WHO (2018), UBA (2/2026).

In an emergency

When the water gets weaker or stops

1. Get informed: switch on the radio or a warning app, check the water supplier's website or fault line. Official advice comes first.
2. Fill up while it still runs: if a longer disruption is looming, fill the bath, washbasins, buckets, pots and containers – above all for flushing the toilet (BBK 2018). As long as there is no boil-water notice, you can fill clean bottles and containers with tap water as extra drinking water.
3. Ration your supply: drinking water first for drinking, then for cooking. Use the non-drinking water for hygiene and the toilet (see the "Priorities" figure above).
4. Save water: disposable crockery instead of washing up, wet and disinfecting wipes for your hands, dry shampoo, kitchen roll instead of a wet cloth. When the toilet no longer flushes: emergency toilet, see Hygiene.
5. In frost: without heating, pipes can freeze and burst (BBK). If a pipe bursts, turn off the water at the main stop tap.
6. Think of your neighbours: pass on what you've heard and ask who needs help – especially older people on upper floors.
7. Use the emergency supply: if the authorities hand out water or open emergency wells, listen out for radio and loudspeaker announcements. Take clean containers with you.

During a boil-water notice – step by step

This is how it is set out in the UBA's template notices, which health authorities and water suppliers use. If your local notice says something different, follow the local one.

1. Read the notice carefully: which area? Which phone number or website for questions? Switch on the radio and listen for loudspeaker announcements. Tell your neighbours.
2. Drink tap water only after boiling it.
3. Boil it properly: bring the water to a rolling boil once and then let it cool slowly for at least 10 minutes. A kettle is handy for this. For most uses, then wait until the water is only lukewarm.
4. Use boiled or bottled water for: drinking and drinks, preparing food, washing and preparing fruit, vegetables and other uncooked food, ice cubes, brushing teeth and cleaning open wounds.
5. Small children, people who are ill and people with weakened immunity: also use boiled and cooled water for personal hygiene.
6. What works without boiling (according to the UBA, as an exception for a short time, with a slightly higher risk): a dishwasher that can be set to 60 °C or dries with heat; a washing machine at 40 °C or more; personal hygiene and cleaning – cover open wounds with waterproof plasters; washing hands thoroughly with plenty of soap. You can use toilet flushing without restriction.
7. When showering, make sure not to swallow any water (CDC).
8. Appliances connected to the water supply, such as water dispensers or ice makers in the fridge, should not be used during the advisory (CDC).
9. Pets get bottled or boiled, cooled water (CDC).
10. Filters do not replace boiling: filtered tap water is also boiled during the advisory (CDC). Do not use water filters for baby formula (Verbraucherzentrale).
11. Careful, hot! Risk of scalding – children, older and ill people in particular often don't notice high temperatures (UBA).

If the notice says "do not drink": then boiling is not enough. Use your supply or bottled water – for drinking, cooking, brushing teeth and wounds. Whether you may shower is stated in the notice.

Treating water from other sources

The safest option is always your supply or bottled water. If you do have to use water whose quality you don't know – for example leftover water from containers of unknown age – proceed like this (following the CDC):

1. Check whether it can be used at all: does the water smell or look like oil, petrol or chemicals, or does it come from floodwater? Then do not use it – no treatment will make it safe.
2. Prepare cloudy water: let it settle and pour off the clear water at the top, or pour it through a clean cloth, paper towel or coffee filter.
3. Boil: bring the clear water to a rolling boil for 1 minute (above about 2,000 metres altitude, 3 minutes), then let it cool. According to the WHO, a rolling boil is enough to inactivate disease-causing bacteria, viruses and protozoa.
4. If you cannot boil: filter with a suitable filter and then disinfect with tablets according to the pack instructions.
5. Store: in clean containers with tight-fitting lids.

Floodwater: never drink it

Floodwater is almost always contaminated: with heating oil, sludge, faeces, chemicals and germs (BBK). Water containing harmful chemicals or toxins cannot be made safe by boiling, disinfecting or filtering (CDC). Even a good outdoor filter won't help here.

• Do not drink floodwater, and do not use it for brushing teeth, cooking, washing up, ice cubes or baby formula.
• Whether tap water is safe after a flood is for the local authorities to say. Until then, use your supply or bottled water (CDC).
• If oil or another hazardous substance is leaking, call the fire brigade immediately (BBK).

More on what to do before, during and after a flood is in the guide Floods. Which supplies can be eaten cold or need little water is in the guide Building up food supplies.

In emergency mode you'll find the most important steps under Emergency.

Sources for this section: UBA recommendation on §§ 62–68 TrinkwV, annexes A.3 and A.4 (2/2026), BBK guide (11/2025), BBK "Hygiene in Notsituationen", BBK "Stromausfall" (2026), BBK "Empfehlungen bei Hochwasser" (2024), BBK guide English edition (12/2018), CDC (2024, 2025, 2026), WHO (2015), Verbraucherzentrale Niedersachsen (9/2026).

Afterwards

When the boil-water notice is lifted

• Only the health authority lifts it – not a neighbour, not a social media post. Before that, it must be shown that the water reliably meets the requirements again; in practice the cause must have been removed and samples must be flawless on three consecutive days (UBA).
• Read the all-clear: sometimes the water can be used normally straight away. If the all-clear says there may still be residual water in the pipes, let the water run until it comes out of the tap cold, colourless, clear and odourless. If anything remains unusual, tell your water supplier (UBA).
• Pass it on: tell housemates and neighbours about the all-clear too.

Restocking

1. Use up opened bottles first.
2. Buy new packs to replace what you drank and put them at the back of the shelf, write the date on them, enter them in your supplies.
3. Empty containers you filled yourself, clean them and refill them – with a new date.
4. Use up the non-drinking water from the bath and buckets for the toilet and cleaning, then clean the containers and let them dry.
5. Add whatever was missing (tablets, containers, disposable crockery, wet wipes) to your shopping list.

Learning from it

After a few days, sit down briefly with everyone in the household: did the water last? Did everyone know where the supply is and where the main stop tap is? Did cooking without electricity work? Did the warning arrive in time? Improving one thing is enough – for example getting a second container or keeping the radio within reach.

Sources for this section: UBA recommendation on §§ 62–68 TrinkwV, annexes A.3 and A.4 (2/2026), BBK "Essen und Trinken bevorraten", CDC "Emergency Water Supply" (6/2025).

Common mistakes

• Thinking only about drinking: without non-drinking water for the toilet and hands, hygiene quickly suffers.
• Forgetting containers for years: replace water you filled yourself every 6 months.
• Storing PET bottles in the sun, in the car or next to petrol: the water takes on smells and tastes.
• Thinking only about drinking during a boil-water notice: brushing teeth, ice cubes, washing fruit and vegetables and baby formula also need boiled water.
• Only warming it briefly: the water must come to a proper rolling boil once.
• Treating a filter as a cure-all: portable filters do not hold back viruses or chemicals.
• Using silver tablets for dirty water: silver alone does not disinfect reliably.
• Boiling floodwater: neither boiling nor filtering helps against oil and chemicals.
• Camping stove in the flat: cartridge stoves and barbecues outdoors only – carbon monoxide is life-threatening.
• Ending the boil-water notice yourself: only the health authority lifts it.
• Leaving hot water unattended: children scald themselves easily.

Checklist

• Drinking water for at least 3 days: 2 litres per person per day
• Goal of 10 days: 20 litres per person
• Extra water planned for pets, hot weather and illness
• Best-before date clearly visible on every pack, entered in your supplies
• Shelf sorted: old at the front, new at the back
• Storage place cool, dark, away from petrol and chemicals
• Self-filled containers food-grade, labelled, dated (replace every 6 months)
• Empty clean containers or buckets for non-drinking water
• Large pot with a lid
• Safe way to cook without electricity (camping stove outdoors only)
• Clean cloths or coffee filters for pre-filtering
• If wanted: filter with a suitable pore size and chlorine dioxide tablets
• With a baby: still water labelled "suitable for preparing infant food"
• Hygiene supply: wet wipes, disinfecting wipes, disposable crockery, bin bags
• Main stop tap found, location noted
• Name, website and phone number of your water supplier on paper
• Warning app installed, battery or wind-up radio
• Yearly date for checking (for example the warning day in September)

Sources

• Federal Office of Civil Protection and Disaster Assistance (BBK): Vorsorgen für Krisen und Katastrophen – guide with checklist (as of 11/2025, 2nd edition), https://www.bbk.bund.de/SharedDocs/Downloads/DE/Mediathek/Publikationen/Buergerinformationen/Ratgeber/BBK-Vorsorgen-fuer-Krisen-und-Katastrophen.pdf?__blob=publicationFile&v=44
• BBK: Essen und Trinken bevorraten (web page, accessed 5 Nov 2026), https://www.bbk.bund.de/DE/Warnung-Vorsorge/Vorsorge/So-koennen-Sie-sich-vorbereiten/Bevorraten/bevorraten_node.html
• BBK: Stromausfall – Vorsorge und Selbsthilfe (edition 4, as of 2026), https://www.bbk.bund.de/SharedDocs/Downloads/DE/Mediathek/Publikationen/Buergerinformationen/stromausfall-vorsorge-selbsthilfe.pdf?__blob=publicationFile&v=11
• BBK: Hygiene in Notsituationen (web page, accessed 5 Nov 2026), https://www.bbk.bund.de/DE/Warnung-Vorsorge/Vorsorge/Gesundheit-und-Hygiene/Hygiene-in-Notsituationen/hygiene-in-notsituationen.html
• BBK: Empfehlungen bei Hochwasser – citizen information (2024), https://www.bbk.bund.de/SharedDocs/Downloads/DE/Mediathek/Publikationen/Risikomanagement/flyer-hochwasser.pdf?__blob=publicationFile
• BBK: Wassersicherstellung (web page, accessed 5 Nov 2026), https://www.bbk.bund.de/DE/Themen/Kritische-Infrastrukturen/Sektoren-Branchen/Wasser/Wassersicherstellung/wassersicherstellung_node.html
• BBK: Disasters Alarm – Guide for Emergency Preparedness and Correct Action (English edition, 6th edition, 12/2018; older version, for filling the bath and containers), https://www.ernaehrungsvorsorge.de/fileadmin/SITE_MASTER/content/Dokumente/ratgeber-englisch-disasters-alarm-3.pdf
• German Environment Agency (UBA): Empfehlungen zum Umgang mit Abweichungen nach Trinkwasserverordnung – Vollzug der §§ 62 bis 68 TrinkwV, annex A.3 "Empfehlung Abkochgebot" and A.4 "Beispielvorlagen für Verbraucherinformation" (as of 11 Feb 2026, editorial changes 4/2026), https://www.umweltbundesamt.de/system/files/document/260417_UBA_Empfehlungen_%C2%A7%C2%A762-68_nach_Freigabe_final_clean.pdf
• Federal Office for Agriculture and Food, portal Ernährungsvorsorge: frequently asked questions – self-filled tap water (web page, accessed 5 Nov 2026), https://www.ernaehrungsvorsorge.de/staatliche-vorsorge/haeufig-gestellte-fragen-faq
• Portal Ernährungsvorsorge: So kann Mineralwasser gelagert werden (web page, accessed 5 Nov 2026), https://www.ernaehrungsvorsorge.de/private-vorsorge/empfehlungen-tipps/so-kann-mineralwasser-gelagert-werden
• Verbraucherzentrale Niedersachsen: Trinkwasservorrat – So sichern Sie die Versorgung im Haushalt (as of 24 Sep 2026), https://www.verbraucherzentrale-niedersachsen.de/wissen/lebensmittel/auswaehlen-zubereiten-aufbewahren/trinkwasservorrat-so-sichern-sie-die-versorgung-im-haushalt-125990
• Centers for Disease Control and Prevention (CDC): How to Make Water Safe in an Emergency (19 Sep 2024), https://www.cdc.gov/water-emergency/about/index.html
• CDC: Make Water Safe During an Emergency – printable fact sheet (undated, accessed 5 Nov 2026), https://www.cdc.gov/water-emergency/media/pdfs/make-water-safe-during-emergency-p.pdf
• CDC: How to Create an Emergency Water Supply (27 Jun 2025), https://www.cdc.gov/water-emergency/about/how-to-create-and-store-an-emergency-water-supply.html
• CDC: About Water Treatment Options When Hiking, Camping, or Traveling (30 Jan 2025), https://www.cdc.gov/drinking-water/prevention/water-treatment-hiking-camping-traveling.html
• CDC: Drinking Water Advisories – An Overview (4 Mar 2024), https://www.cdc.gov/water-emergency/about/drinking-water-advisories-an-overview.html
• CDC: Safety Guidelines – Reentering Your Flooded Home (updated 24 Aug 2026), https://www.cdc.gov/floods/safety/reentering-your-flooded-home-safety.html
• World Health Organization (WHO): Boil water – technical brief (14 Jan 2015), https://www.who.int/publications/i/item/WHO-FWC-WSH-15.02
• WHO: Alternative drinking-water disinfectants – bromine, iodine and silver (10 Mar 2018), https://www.who.int/publications/i/item/9789241513692