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Guide · GUIDE 19

Protection in a dam failure

Last reviewed on 22.06.2026

If a dam breaks or overflows, a flood wave races down the valley and can reach lower-lying settlements within a short time. For emergencies, the federal government operates the water alarm system: in the endangered areas downstream of dams there are dedicated sirens. The water alarm is a signal of its own – twelve low continuous tones of 20 seconds each with pauses of 10 seconds. Anyone who hears it leaves the endangered area immediately.

What do I do when the water alarm sounds?

  1. The water alarm (12 low tones of 20 s, pauses of 10 s) means: act immediately
  2. Do not wait for further information
  3. Leave the endangered, lower-lying area without delay
  4. Flee to higher ground as quickly as possible
  5. Warn and take others with you, do not go to fetch anything

Before: prepare

  1. Know whether you live in a water-alarm zone downstream of a dam
  2. Be able to distinguish the water alarm from the general alarm
  3. Define an escape route to higher ground in advance
  4. Heed your municipality's leaflets on the water alarm

After: returning

  1. Only return once the authorities give the all-clear
  2. Have undermined or damaged buildings checked before entering
  3. Watch for debris flows, mud and damaged infrastructure

What equipment do I need for a dam failure?

On a water alarm speed counts, not equipment – more important than any device is a pre-defined, practised escape route upwards.

  1. A pre-defined escape route to higher ground, known to the children too
  2. Emergency bag within reach that you can grab on the way out
  3. Sturdy shoes and a lamp for the escape (at night too)
  4. Charged phone for the all-clear – but only get informed once in safety
  5. Knowledge of the water-alarm zone and the municipality's assembly points

Common mistakes

  1. On a water alarm, listening to the radio first or waiting for information
  2. Going to fetch valuables or packing instead of fleeing immediately
  3. Confusing the water alarm with the general alarm
  4. Staying in the valley or even returning to it
  5. Never having defined or practised the escape route upwards

Official sources