Loss Prevention

Five facts about floods

flood sign

1. Understanding the hazard & types of floods

Majority of floods are both predictable and inevitable, though flood loss is preventable. In the U.S. and other parts of the world, local flood maps are available. Flood zones are marked by the use of historical and hydrological data. In the U.S. common flood zones that are referenced are 100-Year Zones (high hazard, 1% annual exceedance) and 500-Year Zones (moderate hazard, 0.02% annual exceedance). In general, flood maps will not show the more likely events such as the 50-Year flood.

The table below shows the probability of flooding occurring over a period of time. For example, a location found in a 100-Year Flood zone has a 26% chance of flooding at least once over a 30-year period. See how this facility's innovative protection methods minimized flood damage to a property located in a 100-Year Flood Zone.

Types of floods

  • Riverine – A river exceeding its natural channel and water spreading to the adjacent land such as when a river overflows its banks.
  • Coastal flooding – Flooding caused by a storm near the coast. This is typically wind driven rain being pushed onto the land, or a storm surge near the coast where coastal water is pushed onto the land. This type of flooding is common during tropical storms or hurricanes.
  • Stormwater – Flooding due to heavy rain that a drainage system (large or small) is not designed for. This is one of the more common types of flooding as it can occur in areas that are not located in FEMA defined flood zones. An example would be the city's stormwater drainage system becoming overwhelmed and backing up.

2. It's just water?

A common misconception is that flooding is just water and, if a building remains upright, it would be easy to dry things out with sunlight and fans. But the truth is that flood water contains animals (e.g., snakes, rodents), debris, dirt, chemicals (e.g., gasoline/oil), and even raw sewage amongst other things. This means that even if your facility was physically flood resistant, water entering the building can still result in very costly remediation and cleaning. Additionally, the risk for water goes beyond just cleanup as a flooded building is at higher risk of developing mold.

3. Practical solutions

When it comes to reducing flood risk, there is no one size fits all. However, simple steps can be taken to reduce the impact of flood. While there are a wide variety of ways to reduce a facilities flood risk, the goal is to keep water out of areas where it can cause the most damage.

  • Elevating critical equipment above the floor by a few inches or move it out of low-lying areas such as a basement.
  • Blocking entry ways with deployable FM Approved barriers such as a drop in place flood wall.
  • Provide curbing to protect critical entry ways.

4. Emergency response planning

A template is available to help you draft a plan to respond to flood at your location. Planning could involve educating yourself and others about what type of flood event you expect at a property in addition to making sure they are prepared to handle it. A FERP (Flood Emergency Response Plan) details what actions need to be taken before and after a flood. Physical flood protection along with a FERP can significantly reduce the flood risk.

5. Flood maps & resources

There are a number of resources available to help you identify flood risk at your facility.

  • NatHaz toolkit – The FM NatHaz toolkit allows you to quickly identify locations potentially exposed to high and moderate risk of flooding. This is done through the Global Flood Map. The proprietary map was developed using public flood information, FM's engineering and research, and hydrology data.
  • Data sheets – The FM Loss Prevention Data Sheet 1-40 Flood covers everything you need to know about when it comes to protecting your property. Information regarding how to identify/understand flood hazards and what can be done to eliminate or reduce the risk can be found here.
  • Understanding the hazard, flood – This is a quick reference guide for flood that discusses what, why, and how (to reduce risk). It is suitable for all levels of knowledge.
  • FM approvals guide – This guide allows you to see all of the various FM Approved flood abatement products available in the market.