What is the term for clear water entering a collection system?

The term for clear water entering a collection system is infiltration. Infiltration refers to the process where groundwater or surface water seeps into sewer systems, particularly when it is associated with clear water sources such as rainwater or runoff. This phenomenon is often problematic in wastewater systems because it can lead to an increase in the flow volume, potentially overwhelming the treatment capacity and affecting system performance.

In contrast, exfiltration describes the process of wastewater escaping from the sewer system into the surrounding soil or groundwater. Stormwater is typically rainwater that flows over surfaces and may enter a collection system, but it does not specifically denote clear water infiltration. Leachate is the water that has percolated through solid waste and typically contains dissolved constituents from that waste, making it irrelevant in this context of clear water entering a collection system.