Short answer
If water comes up through the floor drain, laundry tub or basement toilet during heavy rain and smells like sewage, it's a sewer backup, which is common where older Anderson neighborhoods have combined sewers. If clear water seeps along the walls or through floor cracks, it's groundwater. Backups need cleanup as contaminated water and a backwater valve. Groundwater needs drainage.
Do this first If water is coming up the floor drain and smells, stay out of it and keep others out. Don’t run water or flush toilets in the house until it stops, because that adds to the backup. If the electrical panel or outlets are near the water, call the utility or an electrician.
Tell them apart
| Clue | Sewer backup | Groundwater |
|---|---|---|
| Where it starts | Floor drain, laundry tub, basement toilet or shower | Along the bottom of the walls, floor cracks |
| Smell | Sewage | Earthy or none |
| Color | Gray or dirty | Usually clear |
| Timing | During or right after heavy rain | Spring and wet spells, often for weeks |
| Stops when | The storm passes and the sewer drains | Weather dries out, or drainage removes it |
Why backups happen in Anderson
Parts of Anderson have combined sewers, which carry wastewater and storm water in the same pipes. In heavy storms those pipes can fill, and water pushes back up private sewer lines into the lowest openings in a house. The city has operated under a federal consent decree since 2002 to control combined sewer overflows, with a 2010 filing laying out more than $160 million in improvements through 2029. See combined sewers and backups.
Why groundwater gets in
Anderson’s dense till holds water, and the soil survey estimates a seasonal water table near the surface under much of the city (USDA NRCS). Water presses in at the floor-wall joint and through floor cracks.
Cleaning up after a backup
Sewer backup water carries bacteria and debris. If the area is small and you choose to clean it yourself:
- Wait for the water to stop rising and avoid using water in the house until it drains.
- Wear rubber boots, gloves and eye protection. Keep children and pets out.
- Remove the water with a wet-dry vacuum or pump, and bag up debris.
- Throw out soaked porous materials: carpet, padding, upholstered items, cardboard and drywall that the water reached.
- Wash hard surfaces with detergent and water, then disinfect them.
- Dry the space with fans and a dehumidifier within a day or two.
- Photograph everything first for insurance.
For large backups, or any contact with the electrical system, call a water damage restoration company.
Cleaning up after groundwater
Groundwater is usually clean. Remove the water, dry the floor and lower walls, and pull up wet carpet and padding. The bigger job is stopping the next one: see water at the floor-wall joint and water through the floor.
The fixes are different
For backups:
- A backwater valve on the main sewer line, installed by a plumber
- Backflow plugs in unused floor drains
- Disconnecting sump pumps and downspouts that drain into the sewer
- A water backup endorsement on your insurance
For groundwater:
- Downspouts and grading first
- Interior drain tile and a sump pump, with a backup
A backwater valve does nothing for seepage at the walls, and drain tile does nothing for sewage at the floor drain. Watch where water appears first during the next heavy rain.
When to call
- A plumber, when sewage comes up a drain, when it happens more than once, or to install a backwater valve. A camera inspection of the main line shows whether roots, a collapse or the city sewer is the cause.
- The city’s sewer utility, when neighbors have backups at the same time. That points to the public main.
- A restoration company, for anything larger than a small area of floor.
- A waterproofing contractor, when clean water seeps in at the walls or floor. See interior drain tile.