Reservoir flooding | Oxfordshire County Council

Reservoir flooding

What to do in the unlikely event of a reservoir flood near you.


A reservoir is usually an artificial lake where water is kept for use. Some reservoirs supply water for household and industrial use, others act as fishing lakes or leisure facilities.

Reservoirs are carefully maintained which means that reservoir-related flooding is very unlikely.

If a reservoir were to fail it may cause flooding similar to that from rivers where the water slowly rises. However, if a reservoir dam were to suddenly fail, a large volume of water could escape at once. It is important therefore, that plans are prepared to deal with this 'worst case' scenario, so that anyone who might be affected by the flooding knows what action to take.

Be prepared

To find out if you live or work in an area that might be affected by reservoir flooding, check the flood map on the Environment Agency's website.

  • Plan where to go if there is a risk of reservoir failure
  • Put together a grab bag of things you might need in an emergency
  • Know who you would need to contact e.g. family members and how
  • Be vigilant and be prepared to act quickly to get yourself to safety

More information on what to do if there's a flood.

If a reservoir fails

If you live or work in an area that could be flooded if a reservoir fails, you will be alerted if there a risk of failure in one or more of the following ways:

  • The emergency services in your area may knock on your door or use a loudhailer system
  • You may be given an evacuation card which will give you specific advice about where to go
  • Helicopter Skyshout (public address system) warnings may be given
  • Local television and radio alerts


If you think you spot any warning signs of a problem with a reservoir you should ring the Environment Agency Incident Helpline: 0800 807 060.

Reservoir planning in Oxfordshire

Work is currently being carried out by Oxfordshire County Council and the Thames Valley Local Resilience Forum on planning for reservoir emergencies. Oxfordshire has one plan across the county to respond to reservoir flooding and is developing specific plans for larger reservoirs across the county.

In March 2011 the Thames Valley Local Resilience Forum held a reservoir flooding day as part of Exercise Watermark. Responders from across the Thames Valley took part in a workshop to explore the topic of reservoir failure and improve their knowledge of the new reservoir flood maps and the specific issues involved in responding to a reservoir failure.

More information

To find our more about Reservoir flooding see the Environment Agency's website which has reservoir flood maps and frequently asked questions.

Last reviewed
29 September 2016
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