Basement Flooding and Sewer Backups in Central Illinois

Why basements here take on water

Macon County's flat glacial ground drains slowly (Wikipedia: Macon County, Illinois). Heavy spring and summer storms saturate the soil and raise groundwater around foundations, and they can overload sewers. The Illinois State Water Survey studies rainfall, flooding and groundwater across the state (Illinois State Water Survey), and the National Weather Service Lincoln office issues flood watches and warnings (National Weather Service Lincoln, IL).

Where is the water coming from?

Through the walls or floor

Seepage at the wall-floor joint, wet cracks or water under the floor points to groundwater. The sump pump and drain tile are the defense.

Up through the floor drain

Water, especially dirty water, rising from the floor drain during a storm points to a sewer backup. A backwater valve is the defense.

Down from outside

Water coming in at window wells or at the top of the wall often means roof runoff and grading are sending water toward the house.

Defenses

• Sump pump sized for the inflow, with a check valve.
• Backup pump on battery or water power for outages.
• Backwater valve on the building sewer.
• Downspouts and grading that move water away from the foundation.
• Disconnecting clear water such as downspouts or sump lines from the sanitary sewer where they are tied in.

The City of Decatur publishes sewer and stormwater information for residents (City of Decatur, Illinois (water, sewer and permits)).

Power outages

Severe thunderstorms bring both heavy rain and power outages. A pump without power is no help. Test backups before storm season.

After water comes in

1. Stay out of standing water if outlets or appliances may be wet; turn power off only if it is safe.
2. Photograph everything.
3. Remove water and dry the space quickly to limit mold.
4. Disinfect anything touched by sewage.

University of Illinois Extension has guidance on cleaning up after flooding (University of Illinois Extension).

Finished basements

Finishing a basement raises the stakes. Before finishing, make sure the sump, backup and backwater valve are in place, and keep access to the sump pit and cleanouts.

Insurance note

Many homeowner policies treat sewer backup and flood differently, and some require a separate endorsement for backups. Check your own policy.

Related pages: sump pumps & basement backups, sewer & main line repair, drain cleaning, and what shapes an estimate.

Sources: Illinois State Water Survey; National Weather Service Lincoln, IL; City of Decatur, Illinois (water, sewer and permits); University of Illinois Extension.