Floods and heavy rain

Floods don't only happen on big rivers. Heavy rain can flood streets, cellars and underpasses anywhere in a short time – even far away from any stream or river. The good news: what protects lives in an emergency is simple. Stay out of the cellar. Stay out of the water. Go upstairs in time. And a lot of what keeps the damage small, you can prepare calmly in advance.

At a glance

• Two kinds of flooding: On larger rivers, a flood usually announces itself hours to days in advance. Heavy rain is local, hard to predict precisely and often leaves very little time.
• Know your risk: Your federal state's flood hazard map shows river flooding; a heavy-rain hazard map (usually from your town) shows flooding caused by rain. A blank spot on the map does not mean water can't get there.
• Stay out of the cellar once water gets in: The door often can't be opened from the inside any more, and there is a risk of a fatal electric shock. Avoid underground car parks, underground stations and underpasses too.
• Switch off the power early to rooms that water could reach – but only if you are standing somewhere dry.
• Never walk or drive through floodwater: Just 15 cm of fast-flowing water can knock a person off their feet, and 30 cm of moving water can float a car.
• Go upstairs – or leave if the authorities tell you to. Higher floors and higher ground give the best protection.
• Afterwards: only go back in when it is safe; take photos before you clean up; have the electrics and heating checked by professionals; dry everything quickly.

Start small

You don't have to buy sandbags or rebuild your cellar today. Pick one of these tasks each day – none takes more than ten minutes, and almost all of them are free:

• Look at the hazard map: Search for "Hochwassergefahrenkarte" and your federal state, enter your address – and ask your town for a heavy-rain hazard map (Starkregengefahrenkarte). Keep a printout or screenshot with your papers.
• Set up warnings: Under Warnings, choose the districts where you live and work – official flood warnings appear there too. Is there a radio with batteries or a crank in the house?
• Where's what: At the fuse box, check which fuses supply the cellar and ground floor. Note the fuse box, main water tap and gas shut-off valve under Where's what, with a photo.
• Cellar walk-round: What down there must not get wet – documents, photos, electrical appliances, chemicals? Take one thing upstairs. The document folder never belongs in the cellar.
• Backflow protection: Is there a backflow valve, and when was it last serviced? If you rent: ask your landlord.
• Read your insurance: Does your contents or buildings policy mention "natural hazards" (Elementarschäden)?
• Flood plan: In the family plan, choose a meeting point on higher ground that you can reach without going through an underpass, and a safe place for the car.

Understanding

River floods and heavy rain

River floods happen when widespread, long-lasting rain – sometimes together with melting snow – makes rivers burst their banks. According to the German federal flood protection guide (Hochwasserschutzfibel), on larger rivers a forecast one to two days ahead and a reliable prediction several hours ahead are possible. On smaller rivers in hilly regions, the warning time shrinks to a few hours.

Heavy rain comes mostly in summer, with thunderstorms. It is local and short, but brings the largest amounts of rain. Small streams then rise very quickly, and the sewers are not designed for such volumes. The water runs off over the surface, collects in hollows and low points such as underpasses and gets into cellars and underground car parks – even far away from any river. There is often hardly any time; you can only act sensibly on the basis of the weather warning, ideally before the rain starts (Hochwasserschutzfibel).

Often overlooked:

• Sewer backflow: If the sewer is overloaded, water is pushed back into the building through the house connection – through floor drains, showers or toilets in the cellar. This happens with heavy rain just as with river floods.
• Rising groundwater: After long wet periods, the groundwater rises, often with a delay, and seeps through leaky cellar walls.
• Storm surges on the coast: they can be forecast well; in Hamburg and Bremen, evacuations are an established part of coastal protection.

How warnings work

Different bodies issue warnings – about different things:

• The German Weather Service (DWD) warns about the weather, such as heavy rain and prolonged rain, down to district or municipality level. Its warnings have four levels: weather warning (yellow), warning of significant weather (orange), severe weather warning (red) and extreme weather (violet).
• The federal states' flood centres measure river levels, calculate forecasts and issue flood warnings. You can see them all in one place on the cross-state flood portal (hochwasserzentralen.de) and in the states' official river-level app. Many states use alert levels (Meldestufen) at the gauges. In Bavaria, for example, level 1 means minor flooding of the banks in places, level 3 means individual built-up plots or cellars are flooded, and level 4 means larger built-up areas are flooded. Which water level belongs to which alert level is set for each gauge individually.
• The NINA warning app of the Federal Office of Civil Protection (BBK) combines DWD weather warnings, flood information from the cross-state flood portal and civil-protection warnings. Bereitsein shows the same official warnings under Warnings for the districts you choose.
• Locally, your town or municipality informs people, often with loudspeaker vans. In particularly dangerous situations, sirens are added (a one-minute rising and falling tone means: danger, find out more) as well as mobile phone alerts via cell broadcast.

What the DWD levels mean for heavy rain (amount of rain in litres per square metre):

Important with heavy rain: The warnings usually cover a whole district, but a thunderstorm cell is often only a few kilometres across. Perhaps it stays dry where you are – perhaps it hits your very street. Warning apps add to your own attention; they don't replace it. And every flood is different; experience from earlier floods can be misleading (Hochwasserschutzfibel).

During a power cut many warning channels stop working – but a radio with batteries, a crank or in the car still works (BBK). More in the guide Warnings and communication.

Reading hazard maps

The federal states produce flood hazard maps and flood risk maps for rivers with significant risk; they are public and free. The details differ from state to state. This is how to read them (example: Bavaria):

• Three scenarios: HQhäufig is a frequent flood, in Bavaria a 10-year flood (not available for all rivers). HQ100 occurs on average once in 100 years – but that doesn't mean the next 99 years will be quiet; it can also happen several times in quick succession. HQextrem is a very rare event, in Bavaria roughly a 1,000-year flood, in which flood defences usually no longer work.
• Colours: Blue areas show where water would stand. The darker the shade, the deeper the water. In Bavaria, yellow to orange areas show land behind dykes that would only flood if the defences failed – dykes don't offer one hundred per cent safety either.
• Hazard and risk: Hazard maps show extent and water depth, sometimes also flow speed. Risk maps also show how the land is used – for example how many people would be affected, or where there are facilities that would endanger the environment if flooded.
• What's missing: Flood hazard maps only show flooding from rivers and streams. Heavy rain, sewer backflow and high groundwater are not included. Missing information on the map expressly does not mean that no flooding can occur there (Bavarian Environment Agency, LfU).

Heavy-rain hazard maps only exist in some places, mostly produced by the municipality, so each one looks different. They show where rainwater can collect or not drain away fast enough, for example in small hollows. The Federal Agency for Cartography and Geodesy advises: where there are local heavy-rain maps, use them – and you only get the full picture if you look at the heavy-rain map and the flood hazard map together.

Don't wait for an emergency to look up the maps: When river levels rise, the portals are often overloaded. Print them out beforehand (Hochwasserschutzfibel).

How water gets into the house

Water finds many ways in: through cellar windows and light wells, through doors and garages, through leaky walls and pipe or cable entries – and from below, through the sewer. This is where the backflow level (Rückstauebene) comes in: it marks how high water in the sewer can rise. Unless the authority sets a different level, it is the height of the road surface at your connection. Anything in the house below it – a floor drain, shower or toilet in the cellar or in a basement flat – can be flooded by backflow. In flood areas, water in the sewer can even rise to the level of the flood (Hochwasserschutzfibel).

Why water is so dangerous

• Force: Just 15 cm of fast-flowing water can knock a person off their feet, 30 cm of moving water is enough to float an average car, and 60 cm will sweep most vehicles away (Natural Resources Wales; for the 30 cm, also the Environment Agency).
• Water pressure: When a cellar floods, the water pushes the door shut – it can no longer be opened from inside (BBK). Even a few tens of centimetres of water can be life-threatening if doors jam or electricity is involved (Hochwasserschutzfibel).
• Electricity: Flooded electrical installations are a danger to life. Only enter flooded rooms if you are sure the power is off (Hochwasserschutzfibel).
• What you can't see and what's in it: open manholes, undermined roads, debris – and heating oil, sewage, chemicals and germs. Never drink floodwater, not even boiled or filtered (see Drinking water).

Sources for this section: BBK guide (11/2025), BBK "Empfehlungen bei Hochwasser" (2024), BBK "Warn-App NINA", Hochwasserschutzfibel (BMWSB, 2/2022), DWD warning criteria, cross-state flood portal, LfU Bavaria (map FAQ, location check, flood warning service), BKG heavy-rain hazard map notes (10/2021), Natural Resources Wales, Environment Agency (12/2019), CDC (8/2026).

Preparing

Assessing your risk

Under the German Water Resources Act, anyone who may be affected by flooding is expected to take precautions within what is possible and reasonable. It starts with these questions:

1. Is your home on the flood hazard map? If so: in which scenario, and how deep would the water be? Is it behind a dyke?
2. Is there a heavy-rain hazard map? Ask your town or municipality. When buying or renting a home, it is also worth asking about the local flood risk (BBK).
3. Where does your home sit in the landscape? In a hollow, at the foot of a slope, by a small stream, at a low point in the road? Street or field names such as "Im Tal" (in the valley), "Mühlenstraße" (mill street) or "Hohlweg" (sunken lane) can also be a clue (Hochwasserschutzfibel).
4. What lies below street level? Cellar, basement flat, underground car park, drains and toilets in the basement – anything below the backflow level is at risk from backflow.
5. Where can water get in? Cellar windows, light wells, cellar door, garage door, pipe and cable entries.
6. What happened in the past? Ask neighbours who have lived there a long time. The Hochwasserschutzfibel explicitly advises newcomers to seek advice from long-standing residents.

Some states bring this together for an address, for example Bavaria with its "Wassergefahren" location check; nationwide, the DWD's natural hazards portal (Naturgefahrenportal) shows warnings and location-based hazards. For a house, independent expert advice can find the ways water gets in and suggest suitable measures (Hochwasserschutzfibel).

Setting up warnings

1. Under Warnings, choose the districts where you live, work and go to school.
2. Install a warning app such as NINA and keep heavy-rain and flood warnings switched on. For river levels there is the states' official, free river-level app (see Recommended apps).
3. Keep a radio with batteries or a crank ready (BBK).
4. Keep your phone reachable, even at night, when a crisis is looming (BBK).
5. If you live by a river: find the nearest gauge. Municipalities set out in their alert plans which measures are needed at which gauge levels (LfU Bavaria) – ask there or ask long-standing neighbours from what level things get critical for you, and note down the number.

Where's what: electricity, water, gas

Everyone in the family should know where the main switches and shut-offs for water, electricity, heating, gas and oil are (Hochwasserschutzfibel). Note them under Where's what, with a photo. Check in the fuse box whether the cellar and ground floor have their own fuses: then you can switch off just these areas – safer for anyone still in the house (Hochwasserschutzfibel).

Protecting the house

The Hochwasserschutzfibel describes three strategies that work in combination: avoiding (moving valuable things higher), resisting (keeping water out) and adapting (fitting things out so water does little damage). Sometimes deliberately letting a building flood does less harm than trying to keep every drop out – if the water outside rises high, it presses on the walls and floor slab. That's why larger alterations should be planned by a professional.

Backflow protection: Backflow valves or lifting units protect all drains below the backflow level (BBK, Hochwasserschutzfibel). Backflow valves must be an approved type, correctly installed and serviced regularly – the Fibel mentions a requirement to service them every six months. The consumer advice centre (Verbraucherzentrale) points out that backflow damage may not be insured without a working backflow device.

Openings: Cellar windows, doors and pipe entries can be sealed, and there are flood-resistant windows, doors and light wells. With such systems, check the maximum water height the manufacturer specifies (Hochwasserschutzfibel). The BBK advises keeping waterproof plywood panels, silicone for sealing doors and windows, and sandbags ready; for higher risk there are mobile systems such as stop-log barriers.

Electricity and heating: The fuse box and gas heating should be in flood-safe areas where possible, i.e. upstairs (BBK). In the cellar and on the ground floor, sockets and cables should be above the expected water level (Hochwasserschutzfibel).

Heating oil tank: Unsecured, partly empty tanks can float up, tip over and tear off pipes – heating oil then leaks out and contaminates the house and surroundings. Tanks must be secured against floating (BBK), and in flood and risk areas there are legal retrofitting requirements. Have existing tank installations assessed for flood risk (Hochwasserschutzfibel).

Equipment: The BBK mentions a pump sump in the cellar and a sewage pump; the Fibel lists, among other things, a submersible pump with a residual-current device, waterproof extension leads, rubber boots and sandbags. The fire brigade and THW need their equipment themselves in an emergency – you can make larger purchases together with your neighbours.

Sandbags: what they can and can't do

Sandbags are cheap, flexible and, after a short briefing, can be filled by laypeople. This is how the Baden-Württemberg State Fire Service College describes it:

1. Fill them half to at most two-thirds full. Fuller bags don't mould to the ground and neighbouring bags and become too heavy. A bag filled two-thirds weighs about 18 to 20 kg.
2. Fold the opening over instead of tying it – that's quicker and is enough once the bag is in place. Bags are only tied if they are thrown or transported loose.
3. Lay them lengthways and staggered like a brick wall, tightly packed, so they form a solid bond. With bags laid crossways, the folded side faces the water.
4. Don't throw them – pass them from hand to hand in a chain.

And this is the honest limit: doors and windows often can't be made watertight with sandbags. In front of doors and windows, however, they act as a filter – much less mud gets into the house, and cleaning up is easier. The fire service experts advise against sealing completely with plastic sheeting, because in many cases water must be able to get into the building for it to remain stable. If water flows over a sandbag barrier, it can give way suddenly (Hochwasserschutzfibel). And after use, sand and bags are almost always contaminated and must be disposed of.

Cellar and ground floor: what goes where

• Documents and irreplaceable things upstairs: Important documents belong outside the danger area (BBK), ideally packed waterproof. What matters first are papers and keepsakes that are hard to replace – not the sofa (Hochwasserschutzfibel).
• Hazardous substances upstairs: Anything harmful to health or the environment, such as solvents or pesticides, also belongs out of the danger area (BBK).
• Make a clearing plan: The Fibel advises deciding in advance – as a list and as a sketch – what goes upstairs in which order in an emergency. Heavy items like the washing machine and dryer can stand permanently on a platform.
• No supplies in the flood zone: Keep water and food supplies in a cellar that doesn't flood – otherwise one floor up (see Drinking water and Building up food supplies).

Insurance: natural hazards cover

In Germany, flooding from rivers or heavy rain and sewer backflow are not included as standard in either buildings or contents insurance. There is an add-on for natural hazards (Elementarschäden) for this, which can usually only be taken out together with the main policy (Verbraucherzentrale, Hochwasserschutzfibel). There is currently no obligation to have it.

• The building is insured by the owner. Contents are insured by whoever lives there. If you rent, ask your landlord whether the building has natural hazards cover (Hochwasserschutzfibel).
• What is usually not covered: groundwater pushing through the walls from below (Verbraucherzentrale).
• Obligations: Working backflow valves are required in rooms at risk of flooding, and drainage pipes on the property must be kept clear. If you neglect this, the insurer may pay nothing or only part (Verbraucherzentrale).
• Car: Flood damage is usually covered by at least partial comprehensive cover (Teilkasko) (Verbraucherzentrale).

Emergency bag and plan

Keep your emergency bag ready for an evacuation: important medicines, documents, a change of clothes, a torch and enough water (BBK). Tick off what goes in which bag under Grab bag. In the family plan you set meeting points, destinations and routes – for floods on higher ground, avoiding underpasses and riverbanks. Municipalities set out flood-free routes, assembly points and emergency shelters in their emergency plans (Hochwasserschutzfibel); ask about them and mark them as important places on the Map. With relief shading and contour lines you can see there where the ground rises. More in the guide Evacuation.

Agree in the family who does what, and remember that not everyone is always at home (Hochwasserschutzfibel). Organise help among neighbours – who helps whom? – because floods can cut off landlines and mobile networks. See the guide Helping your neighbours.

Variations for your household

Ground-floor or basement flat, or a cellar storage room

• Only keep things in the cellar storage room that can get wet.
• Drains, showers and toilets below street level are at risk from backflow – ask about backflow protection and servicing.
• Talk to neighbours on upper floors about whether you could go up to them in an emergency.
• You take out natural hazards cover for your own contents yourself, not your landlord.

House

• Insure the building and contents, as damage can occur despite all precautions (BBK).
• Clean drains and gullies regularly, have backflow valves serviced (Hochwasserschutzfibel).

Underground car park and car

• If there is a risk of flooding, move the car out of the garage or underground car park to a safe, higher place in good time (Hochwasserschutzfibel) – as long as this can be done safely. If there is already water in the underground car park, stay out (BBK).

With children

• Make children aware of the particular dangers and agree where they go if they are out – perhaps the way to relatives or friends is shorter and safer (Hochwasserschutzfibel).
• Don't let children play in floodwater or on flooded areas, nor with toys that were in the water and haven't been disinfected. Even shallow standing water can be dangerous for small children (CDC).
• Take their worries seriously and explain honestly what is happening (BBK). More in the guide Children in a crisis.

With care needs or a disability

• Think about what you need if you have to leave the house quickly: mobility aids, glasses or hearing aid, spare batteries, medication plan and supply, emergency contacts, emergency ID card (BBK).
• If you can't use escape routes on your own: who will support you, and how? Talk about it with your neighbours, family and friends (BBK).
• Floods can also cause power cuts. More in the guides Getting through a power cut and People who need care, and pets.

With pets

• If there is danger, pets come upstairs with you or out of the danger zone (Hochwasserschutzfibel, GOV.UK).
• Find out in advance where animals can stay, and store food safely (Hochwasserschutzfibel). Keep a carrier, lead, food and water to hand.

Without a car

• Arrange a lift with friends, family or neighbours in advance (CDC).
• During ordered evacuations, municipalities take people from flood-safe assembly points to emergency shelters (Hochwasserschutzfibel). Ask where your assembly point is, and plan a walking route there – without an underpass.

Sources for this section: BBK guide (11/2025), BBK "Empfehlungen bei Hochwasser" (2024), Hochwasserschutzfibel (BMWSB, 2/2022), LfU Bavaria (location check), Naturgefahrenportal (DWD), Baden-Württemberg State Fire Service College (7/2014), City of Stuttgart (6/2024), Verbraucherzentrale (7/2026, 8/2026), CDC (8/2026), GOV.UK.

In an emergency

Emergency mode has the short version: Emergency – flood. Instructions from the authorities and emergency services always come first.

When there is a heavy-rain or flood warning

1. Stay informed: warning app, radio, loudspeaker announcements. By rivers, follow the flood centres' reports and the gauges. Charge your phone (Hochwasserschutzfibel).
2. Move the car to safety: out of the underground car park and garage to higher ground – only as long as there is no water yet.
3. Clear the cellar while it is dry: take upstairs what must not get wet. If there is already water in the cellar: don't go in – danger to life (Hochwasserschutzfibel, City of Stuttgart).
4. Switch off the power to rooms at risk early, at the fuses for the cellar and ground floor (BBK). Switch off electrical appliances in the danger area or put them up high. If danger is acute – or if the authorities tell you to – turn off the main gas, water and electricity supplies if it is safe to do so; remember the fridge and freezer (Hochwasserschutzfibel, GOV.UK).
5. Put protection in place: seal cellar windows and doors, lay sandbags, secure the heating oil tank and equipment – but only as long as you are not standing in water.
6. Warn and help others: tell your neighbours, bring children and older people to safety (BBK).
7. Get your emergency bag ready and prepare for an evacuation (BBK).

When the water comes

1. Never go into the cellar, the underground car park or an underpass. If the cellar floods, the door can no longer be opened from inside, and there is a risk of a fatal electric shock (BBK).
2. No light switches, no appliances while you are standing in water (GOV.UK, CDC). If you can only reach the fuse box through water, leave it alone – call 112 if there is danger, otherwise an electrician later.
3. Go upstairs: to higher floors, with family, pets, emergency bag and documents (BBK, GOV.UK).
4. If lives are in danger, call 112. If 110 and 112 don't work, go to the nearest police station or hospital if possible (BBK). If you are trapped, make yourself noticed at the window – Signal helps with a light and a whistle tone, even without a network.
5. If heating oil or another hazardous substance leaks, call the fire brigade immediately (BBK).

Go up or get out?

In floods, heavy rain and flash floods, higher ground or higher floors give the best protection (BBK). Whether you go upstairs or leave the house depends on the situation:

• Evacuation ordered? Then you go – quickly and as the authorities say. An evacuation is only ordered when there is serious danger to life and limb, and there is usually little time (Hochwasserschutzfibel). The steps are in the guide Evacuation.
• Water already rising in the house or in the street? Don't go out through the water. Go upstairs and stay there until help comes or the water goes down. If lives are in danger, call 112.
• Still dry, but a warning is active? Stay informed, keep your emergency bag ready, move the car in time, clear the cellar – and leave at once if told to.

Out and about, and in the car

• Never drive or walk through flooded roads. Turn around and find another route (Environment Agency). The road surface may be undermined, manhole covers washed away can leave open shafts, and the water depth is often underestimated (Baden-Württemberg State Fire Service College).
• Avoid underpasses, underground car parks, underground stations and riverbanks, and respect barriers (BBK).
• Keep away from electricity: Don't drive through water with power lines in it, and never touch fallen lines (CDC).
• Swimming doesn't help: Floodwater is a drowning risk for everyone, even strong swimmers – and even shallow, fast-moving water can be deadly (CDC).
• For thunderstorms, storms and hail when you're out, see the guide Severe weather.

Sources for this section: BBK guide (11/2025), BBK "Empfehlungen bei Hochwasser" (2024), Hochwasserschutzfibel (BMWSB, 2/2022), Baden-Württemberg State Fire Service College (7/2014), City of Stuttgart (6/2024), Environment Agency (12/2019), GOV.UK "What to do during a flood", CDC (8/2026).

Afterwards

Going back into the house

• Only when it is safe: After an evacuation, only once it has been given the all-clear. With badly affected buildings, check whether there is a risk of collapse – if in doubt, don't go in and call in an expert (Hochwasserschutzfibel, CDC).
• Return in daylight, with a torch rather than a candle (CDC). Only enter flooded areas if you have a secure footing, stairs and floors will hold and the power is off (Hochwasserschutzfibel).
• Electricity: If you can reach the main switch from a dry spot, switch it off. If you'd have to step into water, call an electrician. Before the power is switched back on, a qualified electrician must check the system (CDC, GOV.UK); have electrical appliances checked (BBK).
• Smell of gas: get out immediately, don't switch anything that could make a spark. If it is safe, turn off the main valve and open the windows, then call the gas emergency service or the fire brigade (CDC).
• Heating: Never restart a flooded heating system yourself – safety devices may fail and there is a risk of carbon monoxide poisoning. Leave it to a specialist firm (Hochwasserschutzfibel).
• Protection: rubber boots or waterproof shoes, gloves and safety glasses, a respirator mask if there is mould. Avoid skin contact with floodwater, cover wounds with waterproof dressings, wash your hands – always before eating (Hochwasserschutzfibel, CDC).

Documenting and insurance

The Verbraucherzentrale sums it up in three words: secure, document, inform.

1. Photos or videos before you clean up – of all damage and of the water line on walls and furniture (Hochwasserschutzfibel, GOV.UK).
2. Make a list of all damaged items before you throw anything away (Hochwasserschutzfibel).
3. Inform your insurer promptly and agree the clean-up with them (Verbraucherzentrale, Hochwasserschutzfibel). Many insurers have claims hotlines.
4. Limit the damage: You are obliged not to let the damage get worse – if there is a little water in the cellar, start scooping it out and drying once you've documented it (Verbraucherzentrale).
5. Beware of scams: The Verbraucherzentrale warns of fake online shops offering pumps or dryers for payment in advance, and of dubious charity collectors.

Pumping out, mud and oil

• Only pump out once the water outside is falling too and no more is flowing in – otherwise water presses on the walls and floor slab from outside, and there is a risk of uplift damage and undermining (Hochwasserschutzfibel, Baden-Württemberg State Fire Service College).
• Mud is best shovelled out while the water is still draining – once dry it sets hard (Hochwasserschutzfibel).
• Oil on the water: The oil must be bound and removed first, then you pump – otherwise the oil film coats the walls permanently. Call the fire brigade (Hochwasserschutzfibel).
• Petrol engines such as generators or pumps must never run inside the house, cellar or garage – carbon monoxide. Outside, keep them at least 6 metres from doors, windows and vents (CDC).

Drying and mould

• Dry everything as quickly as possible to avoid structural damage, mould and pests (BBK). Ventilate well; drying equipment is often needed, and drying can take several weeks (Hochwasserschutzfibel).
• Place fans at a window or door so they blow air outwards – not inwards, so mould isn't spread around (CDC).
• Anything that can't be dried within 24 to 48 hours should be thrown away (German Environment Agency, UBA).
• If the house was flooded and closed up for several days, assume there is mould (CDC). In warm weather it can form within a few days (Hochwasserschutzfibel).
• In walls and floors with several layers, every layer has to dry; sometimes outer layers have to come off. There are firms that specialise in drying buildings, and if oil has soaked into the masonry, an expert is needed (Hochwasserschutzfibel).

Water and food

• Throw away food that has touched floodwater (CDC, GOV.UK). If the power was off for a long time, check the fridge and freezer – see the guide Getting through a power cut.
• Only drink tap water again once the authorities or the water supplier say it is safe; until then use your supply or bottled water. Watch out for boil-water notices (radio, local council). Never drink floodwater itself. Everything on this in the guide Drinking water.
• Private wells should be disinfected after flooding and the water quality tested (Hochwasserschutzfibel).

Car

If a vehicle stood in water up to the oil sump or above the wheels, don't start the engine again – have it towed to a garage (Hochwasserschutzfibel).

Learning from it

Once the worst is over, ask yourselves what the Hochwasserschutzfibel recommends asking before rebuilding: Where did the water come from? How much time did we have? Did our measures make sense – and did anyone put themselves in danger? Then restock your emergency bag, update the family plan and improve one thing. Fear and uncertainty afterwards are normal; help in the guide Stress and anxiety in a crisis.

Sources for this section: BBK "Empfehlungen bei Hochwasser" (2024), Hochwasserschutzfibel (BMWSB, 2/2022), Baden-Württemberg State Fire Service College (7/2014), Verbraucherzentrale (8/2026), German Environment Agency (6/2013), CDC (8/2026), GOV.UK "What to do after a flood".

Common mistakes

• "There's no river here": Heavy rain can flood cellars and streets anywhere.
• Relying on the map: Flood hazard maps don't show heavy rain or sewer backflow.
• Popping down to the cellar to save something when water is already coming in.
• Driving through water – "it's only ankle-deep". 30 cm of moving water can float a car.
• Fetching the car from the underground car park when there's already water in it.
• Using switches while standing in water.
• Never having the backflow valve serviced – or not having one at all.
• Pumping out the cellar while the water outside is still rising.
• Not taking photos before cleaning up.
• Switching the heating or electricity back on yourself after the flood.
• Forgetting neighbours who can't get upstairs or out on their own.

Checklist

• Looked at the flood hazard map for your address and printed it
• Asked the town about a heavy-rain hazard map
• Assessed where the house sits: hollow, stream, slope, cellar below street level
• Warnings set up for the districts where you live and work, warning app installed
• Radio with batteries or a crank
• Nearest gauge and critical water level noted (by rivers)
• Fuse box (fuses for cellar and ground floor), main water tap, gas and oil shut-offs under "Where's what"
• Backflow protection in place and serviced regularly (or asked the landlord)
• Heating oil tank secured against floating and assessed
• Documents, keepsakes and chemicals moved up from the cellar
• Clearing plan for the cellar: what goes upstairs first
• If needed: sandbags, plywood panels, silicone, submersible pump with residual-current device, rubber boots
• Insurance checked: natural hazards cover for contents and building
• Emergency bag with medicines, documents, change of clothes, torch and water
• Meeting point on higher ground and a route without underpasses in the family plan
• Safe parking place for the car away from underground car parks and hollows
• Municipal assembly point and emergency shelter known
• Help among neighbours agreed: who helps whom?
• Children know the rules: not into the water, not into the cellar

Sources

All links checked on 5 November 2026.

• Federal Office of Civil Protection and Disaster Assistance (BBK): Vorsorgen für Krisen und Katastrophen – Ratgeber mit Checkliste (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: Empfehlungen bei Hochwasser – Bürgerinformation (2024), https://www.bbk.bund.de/SharedDocs/Downloads/DE/Mediathek/Publikationen/Risikomanagement/flyer-hochwasser.pdf?__blob=publicationFile
• BBK: Warn-App NINA (web page, accessed 5.11.2026), https://www.bbk.bund.de/DE/Warnung-Vorsorge/Warn-App-NINA/warn-app-nina_node.html
• Federal Ministry for Housing, Urban Development and Building (BMWSB): Hochwasserschutzfibel – Objektschutz und bauliche Vorsorge (as of February 2022, 9th edition, reprint 2024), https://fib-bund.de/Inhalt/Themen/Hochwasser/2022-02_Hochwasserschutzfibel_2024.pdf
• German Weather Service (DWD): Warnkriterien (web page, accessed 5.11.2026), https://www.dwd.de/DE/wetter/warnungen_aktuell/kriterien/warnkriterien.html
• DWD: Naturgefahrenportal (web page, accessed 5.11.2026), https://www.naturgefahrenportal.de/
• Länderübergreifendes Hochwasserportal (joint service of the federal states, web page, accessed 5.11.2026), https://www.hochwasserzentralen.de/
• Bavarian Environment Agency (LfU): Allgemeine Fragen zu Hochwassergefahren- und Hochwasserrisikokarten (web page, accessed 5.11.2026), https://www.lfu.bayern.de/wasser/hw_risikomanagement_umsetzung/faq_karten/index.htm
• LfU Bavaria: Standortauskunft Wassergefahren – Wassergefahren für Haus und Grundstück (web page, accessed 5.11.2026), https://www.lfu.bayern.de/wasser/hw_ue_gebiete/hwgefahr_pruefen/index.htm
• LfU Bavaria: Hochwassernachrichtendienst – Organisation und Meldestufen (web page, accessed 5.11.2026), https://www.lfu.bayern.de/wasser/hochwassernachrichtendienst/organisation/index.htm
• Federal Agency for Cartography and Geodesy (BKG): Allgemeine Informationen und Nutzungshinweise zur Hinweiskarte Starkregengefahren (10/2021), https://sg.geodatenzentrum.de/web_public/gdz/dokumentation/deu/Starkregengefahrenhinweiskarte_Hinweise.pdf
• City of Stuttgart: Eigenvorsorge gegen Hochwasser und Starkregen (as of 27.6.2024), https://www.stuttgart.de/leben/sicherheit/bevoelkerungsschutz/starkregen/eigenvorsorge-gegen-hochwasser-und-starkregen.php
• Baden-Württemberg State Fire Service College (Landesfeuerwehrschule): Hinweise zum Einsatz von Sandsäcken bei Hochwasser (edition July 2014; provided by the town of Bretten), https://www.bretten.de/sites/default/files/Hinweise_Einsatz_Sandsaecke.pdf
• Verbraucherzentrale: Versicherungsschutz gegen Elementarschäden (as of 31.7.2026), https://www.verbraucherzentrale.de/wissen/geld-versicherungen/weitere-versicherungen/versicherungsschutz-gegen-elementarschaeden-11440
• Verbraucherzentrale: Hochwasserschäden am Haus? Das sollten Sie jetzt tun (as of 14.8.2026), https://www.verbraucherzentrale.de/wissen/geld-versicherungen/weitere-versicherungen/hochwasserschaeden-am-haus-das-sollten-sie-jetzt-tun-62827
• German Environment Agency (UBA): Wasser weg, was nun? (10.6.2013), https://www.umweltbundesamt.de/themen/wasser-weg-was-nun
• Centers for Disease Control and Prevention (CDC): Preparing for Floods (updated 24.8.2026), https://www.cdc.gov/floods/safety/index.html
• CDC: Floodwater After a Disaster or Emergency (updated 24.8.2026), https://www.cdc.gov/floods/safety/floodwater-after-a-disaster-or-emergency-safety.html
• CDC: Safety Guidelines – Reentering Your Flooded Home (updated 24.8.2026), https://www.cdc.gov/floods/safety/reentering-your-flooded-home-safety.html
• Natural Resources Wales: What's in floodwater? (information sheet, undated, accessed 5.11.2026), https://cdn.cyfoethnaturiol.cymru/682809/whats-in-flood-water-information-sheet.pdf
• Environment Agency (GOV.UK): Driving complacency – 74% of drivers would risk life in flood water (press release, 19.12.2019), https://www.gov.uk/government/news/driving-complacency-74-of-drivers-would-risk-life-in-flood-water
• GOV.UK: What to do during a flood (web page, accessed 5.11.2026), https://www.gov.uk/help-during-flood
• GOV.UK: What to do after a flood (web page, accessed 5.11.2026), https://www.gov.uk/after-flood