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Infiltration and inflow
What is infiltration and inflow (I/I)?

I/I is clear water - stormwater and groundwater - that enters the wastewater system. It overloads the system and can cause costly sewer backkups into homes and buildings. I/I can also cause sewer overflows into rivers and lakes.


With over 2,000 miles of sewer and hundreds of thousands of service connections, there's plenty of opportunity for I/I to sneak in. Most of the I/I comes from private sources, including defective sewer service lines and improperly connected sump pumps, downspouts, and foundation drains.

Don't let clear water into the wastewater system. It costs you in many ways.
  • Causes sewer backups into homes
  • Causes sewer overflows into rivers and lakes
  • Increases sewer and utility fees
  • Increases the need for larger and more expensive sewer pipes and treatment facilities
What is the County doing?
  • Routine cleaning and maintenance
  • Using robotic cameras to inspect pipes for cracks and roots
  • Installing liners in old pipes to seal them back up
  • Digging up and replacing pipes that are broken beyond repair
  • Repairing cracks and holes in manholes
  • Raising manhole covers in areas that are prone to flooding
How can property owners help?
  • Inspect and repair damaged sewer service lines
  • Replace older clay pipes that are beyond their service life
  • Make sure sump pumps and building drains are not connected to the sanitary sewer system
  • Cap your cleanout
Rain gutters, sump pumps, and floor drains shouldn't be connected to the sanitary sewer system.
Reduce your risk of a sewer backup.
  • Only flush the 3 Ps (poop, pee, and *toilet* paper)
  • Don't flush "flushable" wipes
  • Don't dump fats, oils, and grease (FOG) in the sink. Can it, cool it, then trash it.
  • Seal basement floor drains

How to properly dispose of common household items


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