Preparing your home for imminent flooding

Heavy rains hit Western Washington in early December, sparking a series of flood warnings.

The series of atmospheric rivers hitting Western Washington this December have sparked flood watches across the state. That includes the National Weather Services’ warning of historic-level flood in the Snoqualmie River Basin.

Our office has previously covered what to do if your home is impacted by a flood and what to know about flood insurance.

What if you know a flood is imminent? Here’s information on how to prepare yourself, and your home, for a high-water event.

Here’s a few tips from the Federal Emergency Management Agency.

Prepping the exterior of your home

• Maintain proper water runoff and drainage. Routinely clean and maintain gutters, downspouts, and splashpads so that rainwater from your roof flows easily away from your home. Also, make sure that any nearby drainage ditches or storm drains are clear of debris and functioning properly.
• Improve lot grading. Determine how water flows or accumulates around your home to identify potential trouble spots (often easy to see during an average rainstorm). Stormwater should always drain away from the building; if necessary, change your landscaping to improve runoff. This may include building up any sunken areas around the foundation, digging small depressions to properly channel water, and otherwise improving the yard so that it slopes away from your home.
• Reduce impervious surfaces around your home. Water runs off concrete and asphalt almost immediately and can exceed the capacity of storm sewers quickly during heavy rains. Retaining and creating natural green space around your home can help reduce sewer overflows by reducing stormwater runoff. Consider options such as rain gardens, vegetated swales, or pervious pavements, which allow more water to be absorbed by the ground.
• Install a rain barrel. A rain barrel is an alternative method for dealing with rainwater. Rain barrels are typically connected to gutter downspouts and collect the runoff from roofs. You can use this stored water for non-potable uses such as watering the lawn and gardens or washing your car.
• Elevate utilities and service equipment. Raise and anchor air conditioning condensers, heat pumps, water meters and other service equipment onto pedestals or platforms that are at least 1 foot above the potential flood elevation. For identified high-risk zones this means going to or above the regulatory flood elevation for the property as adopted by the local community. This inexpensive action can help prevent significant damage and disruption following a flood event.
• Anchor outdoor fuel tanks. Attach outdoor fuel tanks to a large concrete slab that weighs enough to resist the force of floodwaters, or install inexpensive ground anchors that are connected across the top of the tank with metal straps. Unanchored fuel tanks can be easily moved and ruptured by floodwaters and pose serious threats to people, property, and the environment. If located in an identified highrisk zone, fuel tanks should also be elevated to or above the regulatory flood elevation as adopted by the local community. If not feasible then all filling and ventilation tubes should be elevated so that floodwaters cannot enter the tank.

Prepping the interior of your home

• Protect your valuable possessions. Move important documents and other valuable or sentimental items to a safer location, well above the potential flood elevation and/or inside watertight containers.
• Seal your foundation and basement walls. Close any foundation cracks with mortar and masonry caulk or hydraulic cement, which expands and fills gaps completely. Seal walls in your basements with waterproofing compounds to avoid seepage. Make sure any floor drains are clear of obstructions.
• Install flood vents. Flood vents are small permanent openings that allow floodwater to flow freely through an enclosure such as a crawlspace or garage. Properly positioned and installed flood vents protect homes during floods by preventing water pressure buildup that can destroy walls and foundations. Flood openings may be required for lower enclosures of homes being built in high-risk flood zones, but they can also be installed in existing homes. Once installed, make sure your flood vents are kept free of debris and will allow the free-flow of floodwater.
• Install a sump pump. Sump pumps, which pump groundwater away from your home, can be an excellent defense against basement seepage and flooding. They draw in the groundwater from around the house and direct it away from the structure through drainage pipes. Be sure to choose a device with battery-operated backup, in case of electrical power failure.
• Prevent sewer backups. Install drain plugs for all basement floor drains to prevent sewer backups. Another recommended option, regardless of the potential flood elevation, is to install sewer backflow valves for all pipes entering the building. These devices, which allow water to flow only one direction, prevent floodwater and wastewater from backing up into your home through toilets, sinks, and other drains. They are available in a variety of designs that range from simple to complex, but they should be installed by a qualified, licensed plumber.

Last-minute reminders

• Activate flood protection devices (turn on sump pumps, close backflow valves, etc.).
• Shut off electricity at the breaker panel.
• Safeguard important paperwork and move furniture, rugs, electronics, and other valuable belongings to upper floors, or at least off the floor of the ground level.
• Elevate major appliances onto concrete blocks.
• Clean gutters, downspouts, and splash pads, along with any nearby drainage ditches or storm drains; clear snow and ice away from foundations.
• Deploy temporary flood barriers, such as portable flood gates or shields, sandbags, inflatable floodwalls, and flood skirts.

What to do before a flood

From the Washington State Department of Health:

• Plan for evacuation including where you are going to go and the route you will follow.
• Prepare your home for a flood. Call your local building department or office of emergency management for information.
• Purchase flood insurance. (Note: Most flood policies don’t go into effect until 30 days after the policy is written.)
• Keep all insurance policies and a list of valuable items in a safe place.
• Take photos or a videotape of the valuables you keep in your home.
• Listen to your radio or television for reports of flood danger.
• Keep your car filled with gas.

Additional resources

• FEMA: Protect your home from flooding
• FEMA’s flood preparedness checklist
• Flood insurance information from the OIC