If your home was built before 1960 and sits on clay soil and a combined sewer, the river gauge is not what floods you. Water gets in under your own floor, through the drain, the cove joint, a foundation crack or a window well. Prevention is mostly a question of which of those routes your house has, and the order you close them in.
The June 2021 storm is the reference case. The National Weather Service reported widespread 3 to 5 inches of rain across metro Detroit, with 6 to 8 inches in places, and listed flooded basements among the impacts (National Weather Service, Metro Detroit flooding, June 2021). FEMA declared a federal disaster for the incident period of June 25 and 26, 2021, on July 15, 2021 (FEMA, Michigan Severe Storms and Flooding (DR-4607-MI)). FEMA also warns that just 1 inch of floodwater can cause $25,000 in damage to a home (FEMA, Protect Your Property From Flooding).
Water in the basement right now
This page is about the next storm. If water is on the floor today, start with our first-hour guide. If it came up a drain and you live in Royal Oak, the Royal Oak sewer backup guide says who to call and who owns the pipe. Claim deadlines are covered in our basement backup claims guide.
Step 1: find out which route water takes into your house
Risk is specific to your block, not your city. Look up your community on the metro risk map, then read the 2026 risk report for why housing age, original clay drain tile and combined sewers drive the ranking. Suburb scores are modeled from housing data, not measured, so treat your score as a prompt to check your own basement, not a verdict.
Four routes cause nearly all of the damage. Sewer or drain backup is when a combined sewer fills faster than it drains and pushes water up the floor drain. Pump failure is when the power dies in the same storm that fills the pit. Groundwater is saturated clay pressing water through the cove joint and cracks. Surface water is roof and yard runoff reaching the wall because of clogged gutters, short downspouts or soil that slopes toward the house.
Stop surface water first, it costs the least
FEMA's basement guidance is plain on the cheap fixes. Extend downspouts with rigid or flexible extensions so roof water lands farther from the foundation, and keep gutters clear because clogs cause serious water damage. Where you add a berm or regrade, the slope should be about 1 inch per foot and extend for at least 10 feet, and changing a property's elevation can require a permit (FEMA, Basement Flood Mitigation).
Window wells are the other easy entry. The same guide calls for sturdy covers to keep out snow, rain and debris, and wells built with gravel bottoms to drain. FEMA's newer homeowner brochure gives the general rule: make sure your yard slopes away from buildings and that water has somewhere to drain (FEMA, Protect Your Property From Flooding).
Keep the pump running when the power goes out
A single pump with no backup stops the moment the lights do. FEMA calls a battery backup pump an inexpensive safeguard against power outages and pump failure, and notes that newer models can alarm when maintenance is needed (FEMA, Basement Flood Mitigation). A southeast Michigan installer puts battery backup work at about $1,500 to $3,500 on a project, and a water-powered backup at $1,500 to $2,500, though the same article gives a lower range elsewhere, so get quotes (Mansour's Innovations, 2026 sump pump installation cost in Southeast Michigan). Our sump pump cost guide breaks the numbers down. Test the pump before every forecast by pouring a bucket of water into the pit.
Block the sewer, then decide what to do about the floor drain
A backwater valve is a gate that stops sewer water from entering the basement. FEMA warns that debris can jam one open, so it needs access for cleaning, and that you should check with your local official first because some communities do not permit them (FEMA, Basement Flood Mitigation). We cover prices and who needs one in the backwater valve guide, because we could not confirm a Michigan price range we trust for this page.
Floor drain plugs and standpipes are a stopgap. FEMA says not to use a plug if you expect flooding to exceed 3 to 4 inches, and that these measures are not absolute solutions. Detroit homeowners should check which city programs help with valves and pumps in our assistance programs guide.
Insurance does not stop water, but it decides who pays
Sewer backup is usually added as an endorsement, and The Zebra puts it at around $50 to $250 a year, with typical limits from $5,000 to $25,000 (The Zebra, Sewer Backup Coverage). It generally does not cover surface-water floods or rain leaking through a cracked foundation, which take a separate flood policy. Our sewer backup insurance guide goes through the endorsement.
Groundwater through the floor is a drainage job
If the cove joint weeps after every heavy rain, the cheap fixes will not hold. One contractor source puts a whole-home interior drainage system at about $8,000 to $15,000, and says price varies with basement size, damage and location (Basement Waterproofing Scientists, Drain Tile Installation Cost). Get more than 1 quote and ask each contractor which of the 4 routes above they are actually solving. Our contractor guide lists what to ask.
When rain is in the forecast
Check the National Weather Service flood watch for your county. Test the sump pump, confirm the backup battery is charged, and clear the floor drain. Move anything valuable off the floor, check that downspouts are clear and extended, and find your main electrical shutoff while the basement is dry. If water does arrive, stay out while the power is on. Shut off power at the panel only if you can reach it without standing in water, and otherwise call a licensed electrician or DTE Energy.
Sources reviewed
Primary sources checked October 2026:
- National Weather Service, Metro Detroit flooding, June 2021, weather.gov.
- FEMA, Michigan Severe Storms and Flooding (DR-4607-MI), fema.gov.
- FEMA, Protect Your Property From Flooding, fema.gov.
- FEMA, Basement Flood Mitigation, fema.gov.
- Mansour's Innovations, 2026 sump pump installation cost in Southeast Michigan, mansoursinnovations.com.
- The Zebra, Sewer Backup Coverage, thezebra.com.
- Basement Waterproofing Scientists, Drain Tile Installation Cost, basementwaterproofingscientists.com.