How US sewage data works

A sanitary sewer overflow is a discharge of raw or partially treated sewage from a collection system before it reaches the treatment plant — out of a manhole, a pipe break, or a relief point. Because a sanitary system has no permitted outfall, an overflow that reaches a waterway is generally an illegal, unpermitted discharge under the Clean Water Act. (Not to be confused with a CSO, a combined sewer overflow, where stormwater and sewage share one pipe by design.)

The federal permit program, created by the Clean Water Act, that regulates who may discharge pollutants into US waters and under what conditions. Every wastewater utility operates under an NPDES permit. Standard permit conditions (40 CFR 122.41) require a permittee to report an overflow that may endanger health or the environment to its permitting authority — typically within 24 hours.

ECHO is EPA's public website for looking up the compliance and enforcement history of regulated facilities — inspections, violations, penalties, and discharge data. It's the public window onto the underlying database (ICIS, below). Sewage Monitor pulls its national sewer-overflow layer from ECHO's Sewer Overflow / Bypass dataset.

The catch: ECHO only shows what states have sent to EPA. EPA itself flags the sewer-overflow dataset as still “in development” and warns it “does not represent all” events. So a blank state in ECHO usually means unreported, not zero.

The national database behind ECHO. When a state (or EPA) records a permit, a discharge report, or a violation, it lands in ICIS-NPDES, and ECHO displays it. The key question for sewage data isn't whether a utility reported a spill to its state — it's whether that report made it into ICIS. Today, for sewer overflows, it often hasn't.

The rule that moves data into the national system. It requires permittees and states to submit NPDES information electronically instead of on paper, and it's phased in:

• Phase 1 (started Dec 2016) — routine Discharge Monitoring Reports. Largely done nationwide.
• Phase 2 — program reports, including Sewer Overflow / Bypass Event Reports. This is the last and least-completegroup. The deadline was pushed to Dec 21, 2025, and in November 2025 EPA granted many states an extension to the statutory maximum of Dec 21, 2028.

That timeline is the single biggest reason the national sewer-overflow picture is patchy: the data type that matters most here is the one that comes online last.

NeT is the suite of web forms EPA hosts itself so permittees can file electronically and have the data flow straight into ICIS. NeT-SewerOverflow is the specific module for overflow/bypass event reports.

Each state picks one of two paths to meet the e-Reporting Rule:

• Adopt EPA's NeT tools — sign an MOU and let permittees report through EPA's forms. Faster to stand up; states that chose this were the ones EPA moved onto the blanket 2028 deadline.
• Build their own system — a state portal that transmits to ICIS via a data node (e.g. Michigan's MiWaters, Ohio's STREAMS, Indiana's TEMPO360). More control, more engineering — and often where the delay lives.

Our coverage page lists, for every non-reporting state, which path it chose and its expected date.

47 states are authorized (“delegated”) to run their own NPDES program — they issue permits and are the ones responsible for transmitting data to EPA. In a few non-delegated places, EPA runs the program directly. Either way, the national data only fills in when whoever runs the program feeds ICIS — which is exactly the step still in progress for sewer overflows.

Sewage Monitor combines EPA ECHO's national feed with data pulled directly from state systems that don't (yet) flow to ECHO — California's CIWQS, Maryland MDE, New York DEC, and North Carolina DWR. That's why those states are far richer on our map than raw ECHO would show, and it's the model for closing the gaps as more states come online.

See who reports today and who's on deck on the data coverage page.