You may have heard the phrase I and I which stands for inflow and infiltration. Inflow and infiltration are terms used to describe the ways extraneous fresh water (groundwater and storm water) enter the sanitary sewer system.
Infiltration occurs when groundwater seeps into the sewer pipes through cracks, leaky joints, or deteriorated manholes. Inflow occurs when water is directed from concentrated sources (sump pumps, perimeter drains and downspout drains) into the sanitary sewer.
The water entering the sanitary sewer system creates two main problems:
First, it consumes sewer system capacity. It is estimated that for every inch of rainfall the average house roof sheds about 650 to 1000 gallons of water.
An 8-inch sanitary sewer can handle domestic wastewater flow from up to 200 homes, but only 8 sump pumps, operating at full capacity, or six homes with downspouts connected to the sewer, will overload this same 8-inch line.
If extraneous freshwater is directed into the sanitary sewer the capacity is overwhelmed, sewers back-up into houses, and the system will eventually overflow releasing raw sewage into the environment. This creates health and safety issues that could have significant costs associated with it.
Secondly, extraneous fresh water that reaches the wastewater treatment plant requires treatment. The size and cost of treatment is increased, it increases wear-and-tear of the equipment, and reduces equipment life span. The added cost of equipment upgrades and operations is then passed onto each customer.
Find your sump pump. If the sump pump is connected to any other pipe in your home, it is most likely improperly connected. The drainage pipe from your sump pump should go from the pump directly outside your home at ground level. When a sump pump is re-plumbed to pump ground water to the yard or storm sewer, that water no longer takes up space in the sewer system.