Flood Readiness: Simple Steps for Your Home

Winter storms, high tides and saturated ground can flood streets and homes across San Mateo County. This page helps owners and renters choose flood protection supplies and get their homes ready.

For alerts, sandbag sites and what to do when a storm is coming, see Flood Preparedness.
Download the Household and Renter Flood Checklist (PDF) Choose supplies

Flood Protection Supplies and How to Choose Them

How Flood Protection Supplies Help

Flood protection supplies work in four ways:

  • Keep water out

    Gutters, drainage, sealants, flood barriers and backflow valves stop water from reaching or entering your home.

  • Remove water and moisture

    Sump pumps, portable pumps and dehumidifiers clear water that gets in and dry out damp spaces.

  • Protect belongings and utilities

    Shelving, utility platforms and waterproof containers keep valuables, appliances and equipment above the water.

  • Stay alert and ready

    Flood sensors warn you early, and cleanup and protective gear help you recover safely.

The right mix depends on where water comes from, how your home is built and what your household needs.

Before You Buy or Install

  • Hire a licensed plumber to install backflow valves, and a licensed electrician to raise outlets, switches or your electrical panel.
  • Check with your city or County building department before you start. Some projects need a permit.
  • Choose a sump pump with battery backup so it keeps working if the power goes out.
  • Raise water heaters, washers, dryers and outdoor AC units at least 1 foot above the level floodwater could reach.
  • Talk with your neighbors before you regrade your yard or extend downspouts toward a property line. Water you move can flood their property.
  • Renters: ask your property owner or manager before you install anything.

Sandbags and Temporary Barriers

Sandbags, flood barriers and door dams can slow water at doors, garage entries and low vents, but they don't seal water out completely. Set them up before a storm arrives.

Find free sandbags and filling tips on Flood Preparedness.

Household and Renter Checklist

Start with the four steps on Flood Preparedness: know your flood risk, sign up for SMC Alert, make a household plan and build your kits. Then get your home ready.

Before winter

  • Ask neighbors, your property owner or the previous owner whether your home or street has flooded before.
  • Clear leaves from gutters, downspouts and the storm drain nearest your home. Use a rake, and never lift a grate.
  • Point downspouts away from your foundation.
  • Move important documents and valuables above the level floodwater could reach, or store them in waterproof containers. Keep digital copies.
  • Photograph or video your home and belongings for insurance.
  • Check your flood coverage. Most home and renters policies don't cover flooding, and new flood policies usually take 30 days to start. Learn more at FloodSmart and United Policyholders.
  • Test your sump pump and its backup battery.

When a storm is forecast

  • Clear gutters and the storm drain by your home again.
  • Move furniture, rugs, electronics and valuables off the floor or upstairs.
  • Set up sandbags or flood barriers.
  • Turn on your sump pump, and close any manual backflow valves.
  • If water is about to enter your home, turn off power at the main breaker, but only if you're standing somewhere dry. Never touch electrical equipment while standing in water.

After a flood

  • Go home only when officials say it's safe.
  • Photograph damage before you clean up, and contact your insurer.
  • Wear boots, gloves, goggles and an N95 mask while you clean.
  • Dry your home within 24 to 48 hours to prevent mold. Use fans and dehumidifiers once the power is safe. Throw away soaked items you can't fully clean and dry.

Tips for Renters

  • Ask your property owner or manager whether the building has flooded before and what they plan to do in a storm.
  • Learn how to report drainage or building problems, and save that number in your phone.
  • Get renters insurance, and check what it covers. Most renters policies don't cover flood damage, but you can buy separate flood coverage for your belongings.
  • Keep essential documents, medications and electronics where you can grab them quickly.

Storm conditions and other details can change quickly. Always confirm with the responsible agency. This page shares general preparedness information and doesn't replace instructions from emergency officials.

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