Signalling for help from a house or flat (e.g. in a flood)

Rescuers in a disaster area deliberately look for signs of people. They travel by boat through flooded streets, go on foot or fly in helicopters. What catches their eye is anything that does not fit the scene: large bright surfaces, lettering, movement and, at night, light.

Three things make a signal visible: size, contrast and movement. A large cloth is better than a small one. Light on a dark background or the other way round is better than similar colours. And a cloth that is moved draws the eye much more strongly than one that just hangs. These are the same rules as for ground signals in the wild.

At night during floods or storms, street lighting often fails. Then any light in a window stands out, and a flashing light even more. Even a small torch or phone light can be seen from a long way off.

Always try the emergency call first. If it does not get through, send a message to trusted contacts with your address and the number of people with you. This helps rescuers plan how many places they need in the boat.

Choose a spot on the highest floor you can reach with a window or balcony facing the street or the water – where boats and vehicles pass by. Hang a bright bedsheet or large towel outside and, if possible, write ‘SOS’ or ‘HELP’ in large letters and the number of people on it. Fix it well so that wind and rain do not tear it away.

As soon as a boat, vehicle or helicopter comes into view, move: wave clearly with the cloth or with both arms and blow your whistle. At night, flash a torch or phone light at intervals. Save battery while doing so, because the wait can be long.

Never walk through floodwater or swim in it to fetch help. Even shallow, flowing water can knock a person over. Debris floats in the water, manhole covers may be missing, and electricity from damaged lines can make the water deadly.

With rising water, do not retreat into a closed attic with no way out. If the water keeps rising, you are trapped there. Official flood guidance says: go to the highest floor, and onto the roof only if it is really necessary – then signal for help from there.

When signalling, do not lean far out of the window, and hold on to children. On roofs, especially steep or wet ones, there is a risk of falling; find a secure hold there. Keep away from power lines. If there is a fire in the building, none of this applies: follow the instructions of the fire service and dispatcher.

You do not need special gear. Bright bedsheets, white or colourful towels, tablecloths or a rescue blanket work well. For lettering use a thick marker, paint or tape, or lay dark clothing as letters on a bright cloth.

A whistle, a torch with spare batteries and a charged phone should always be within reach at home, for example in your emergency bag. In flood-prone areas it is worth moving these things to an upper floor in advance.

Some communities have systems with which households show ‘all OK’ or ‘help needed’ after a disaster, for example coloured cards in the window. Only use such a sign if it is known and agreed locally; otherwise it can be misunderstood.

Once everyone has left the building, take the signal down or cross it out clearly, if this can be done safely. A forgotten ‘SOS’ sheet can lead rescuers back to an empty house later while people elsewhere are waiting.

For the same reason: only hang out help signs when help is really needed. In a disaster, boats and helicopters are scarce. Every unnecessary trip costs time that others need.

Tell the rescuers if other people or pets might still be stuck in neighbouring houses. You may have seen things they do not know.