Floods and River Crossings

Respect moving water, before, during and after

7 minBeginnerUpdated 2026-10-23 Floods and River Crossings

You will learn

Prepare a household for a flood warning
Understand why walking or driving into floodwater kills
Stay safe after a flood and cross a river only when there is no other way

⚠️ Never walk, swim or drive into floodwater. Moving water as shallow as 15 cm can knock you over and 30 cm can float a car.

⚠️ Do not touch electrical switches or equipment while standing in water, and stay away from fallen power lines.

⚠️ Avoid river crossings whenever possible. If in doubt, wait or turn back.

Before: act on the warning

Floods often give some warning, and that time is precious. Know your national alert service and sign up for warnings: in Portugal that is ANEPC and the IPMA weather warnings, elsewhere your own civil protection or environment agency. When a flood is forecast, move people, pets, documents and valuables upstairs or to higher ground, and bring in anything outside that could float away. Keep a go bag ready with medicines, water, a torch, a charger, copies of documents and warm clothes. Turn off electricity and gas at the mains only if you can do it safely and the area is still dry. Never touch switches or the fuse box while standing in water. If you are told to evacuate, go straight away.

💡 Find out now whether your home or your route to work is in a flood zone.

During: turn around, don't drown

Most flood deaths happen when people walk or drive into floodwater. Moving water is far stronger than it looks. Just 15 cm of fast-flowing water can knock an adult off their feet. About 30 cm of water can float a car, and around 60 cm will sweep most vehicles away, including large 4x4s. You also cannot see what is under the surface: the road may have washed away, a manhole cover may be missing, and the water may carry debris, sewage or live electricity. If a road or path is flooded, do not enter it. Turn around and find another way. If water rises around you, move to the highest floor or the roof, not the attic where you could be trapped, and call the emergency number.

💡 Turn around, don't drown. No journey is worth driving into floodwater.

After: the hidden dangers

When the water goes down, the danger stays. Floodwater is usually contaminated with sewage and chemicals, so keep children out of it, wear gloves and boots, and wash your hands well. Treat tap water as unsafe until the authorities say otherwise, and boil it or use bottled water. Do not switch on electricity until a qualified electrician has checked the system, and stay away from fallen power lines. Throw away food that touched floodwater. Dry the house quickly with ventilation, because mould starts growing within a day or two and harms the lungs. Photograph the damage for insurance before you clear it, and return home only when told it is safe.

Crossing a river on foot

The safest river crossing is the one you do not make. Look for a bridge, wait for the level to drop, which often happens overnight after rain, or turn back. If you must cross, choose a wide, shallow, slow section, ideally where the river splits into several braided channels, and stay below knee depth. Never cross just above rapids, a weir or a waterfall. Unclip your rucksack hip belt and chest strap so you can shed it if you fall. Face upstream, lean slightly into the current, and shuffle sideways, using a strong stick as a third leg. In a group, link arms and cross together, the strongest person upstream. If you are swept away, float on your back with your feet pointing downstream to fend off rocks, and steer towards the bank. Never try to stand up in fast water, as your foot can be trapped.

💡 If you have to ask yourself whether it is too deep or too fast, it is.