Short answer
Parts of Anderson have combined sewers that carry storm water and wastewater in the same pipes. In heavy rain they can fill up and push water back through the lowest drain in a house, often a basement floor drain. A backup smells, comes up the drain and is contaminated. Groundwater seeps in at the walls and floor. The fixes are different.
How a combined sewer works
In a combined system, the same pipes carry wastewater from homes and businesses and rain water from streets and roofs. In dry weather, everything flows to the treatment plant. In heavy storms, the pipes can fill faster than they drain. When that happens, the system relieves the pressure at overflow points along the river, and some of the water can push backward up private sewer lines into the lowest openings in buildings, usually basement floor drains, laundry tubs and basement toilets.
Parts of Anderson’s sewer system work this way. In 2002 the city entered a federal consent decree (United States v. City of Anderson) requiring a long-term control plan for combined sewer overflows. A 2010 court filing to modify that decree laid out more than $160 million in sewer and treatment-plant projects in three phases, with completion by December 31, 2029.
Source: U.S. District Court, Southern District of Indiana, case 1:02-cv-01103, First Modification to Consent Decree (filed 2010), as published by the U.S. EPA.
Backup or groundwater?
They look alike on the floor but have different causes and fixes. A backup comes up through the floor drain or basement fixtures during heavy rain and smells of sewage; groundwater seeps in clear along the walls and through floor cracks. Our sewer backup or groundwater? guide walks through the checks and what to do in the moment.
Is your street on the combined system?
Not every address is on the combined part of the system. The City of Anderson’s wastewater utility can tell you what serves your address, and whether your neighborhood is affected by the long-term control plan’s projects. If you’re on a combined sewer and have a basement floor drain, plan for backups even if you’ve never had one.
Protecting a basement from backups
- A backwater valve. A plumber installs a one-way valve in the main sewer line from the house. It closes when sewer water tries to flow back in. It needs a permit in many places and a cleanout for maintenance. Ask the city about requirements before installing one.
- Plug unused drains. A floor drain you never use can be fitted with a backflow plug.
- Keep clean water out of the sewer. Sump pumps and downspouts tied into the sewer add to the overload in storms. Many older homes have these hidden connections. Have a plumber trace them, and send that water to the yard. See sump pump discharge.
- Raise what matters. Keep the washer, dryer, water heater and stored valuables off the floor where you can.
- Check your insurance for a water or sewer backup endorsement.
Don’t confuse the two fixes
A backwater valve won’t stop water seeping through the walls, and drain tile won’t stop sewage coming up the floor drain. Some Anderson basements need both. Start by watching where the water first appears during the next heavy rain.
Questions for the city or a plumber
- Is my address served by a combined or a separate sewer?
- Has my street had backups, and are projects planned nearby?
- Do I need a permit for a backwater valve, and who inspects it?
- Is my sump pump or any downspout connected to the sewer?
During a flood, backups and river water can arrive together. See White River flooding, and the first-hour checklist for what to do while it’s happening. Where the sewer and the water table are both problems, the nearby towns page and flood zones help sort out what applies to your street.