EPA distinguishes infiltration — groundwater entering through defective pipes, joints, or manholes — from inflow — stormwater entering through direct connections — though most agencies track the two together, since it's hard to isolate each source's contribution in the field. Excess I&I eats into a system's usable treatment capacity and is a leading contributor to sanitary sewer overflows, a Clean Water Act violation that many agencies now manage under a formal Capacity, Management, Operation, and Maintenance (CMOM) program, often mandated by a state agency or a consent decree. Because CIPP, pipe bursting, manhole rehabilitation, and point repairs are the standard toolkit for reducing I&I, an active I&I reduction program tends to generate a steady, recurring stream of sewer rehabilitation bid work rather than a single one-off project. For contractors specializing in trenchless rehab, I&I reduction programs are exactly the kind of repeatable project type worth tracking across multiple agencies and bid cycles — which is the pattern Nonlinear is built to surface as it reads bid documents and capital plans across a territory.
Knowledge Base
What is I&I (inflow and infiltration)?
Inflow and infiltration (I&I) is extra, unwanted water that gets into a sanitary sewer system from sources other than actual wastewater — infiltration through cracked pipes and joints, inflow through direct connections like sump pumps and roof drains — and it's one of the main drivers of sewer rehabilitation spending nationally.
