Sewer Overflow FAQ

Generally, no — not until water testing confirms that bacteria levels have returned to safe levels. After a sewer overflow reaches a waterway, bacteria counts (particularly E. coli and enterococcus) can spike to levels hundreds or thousands of times above safe swimming thresholds. Health departments typically recommend avoiding contact with water in the affected area for at least 72 hours after a reported overflow, though the actual recovery time depends heavily on rainfall, water flow, sunlight, and temperature.

The 72-hour guideline is a rough heuristic, not a guarantee. In slow-moving or enclosed water bodies (lagoons, coves, harbors), bacteria can persist for days longer. Conversely, in fast-flowing rivers with direct sunlight, levels may return to safe ranges more quickly.

The safest approach: check with your local health department for posted advisories before swimming, kayaking, or surfing in any area where an overflow has been reported. Many coastal counties have automated advisory systems tied to overflow notifications. If no advisory has been issued but you know an overflow occurred nearby, apply the 72-hour rule yourself.

This is a crucial question that gets at the heart of the infrastructure crisis.

Modern separate sanitary sewer systems are designed to carry only sewage — household and industrial wastewater. They are not supposed to receive stormwater. Their pipes are sized based on anticipated sewage flows from the buildings they serve, with some design safety margin. Under normal conditions, they should never overflow.

The problem is inflow and infiltration (I/I). Over decades of use, sewer pipes develop cracks, joints separate, and holes form. Groundwater seeps in through these openings constantly (infiltration). During and after rainstorms, stormwater actively enters through holes, broken pipe sections, uncapped cleanouts, and improper connections (inflow). Additionally, some older properties have sump pumps or foundation drains illegally connected to the sanitary sewer, dumping large volumes of groundwater directly into the system during wet weather.

The result: a system designed for sewage is receiving multiples of its design flow during storm events. Pump stations are overwhelmed. Low points in the collection system — particularly near waterways — overflow first. The system acts like a pressurized container that relieves itself at its weakest or lowest points.

The solution — fixing the I/I — requires inspecting miles of underground pipe with cameras, repairing or replacing defective sections, rehabilitating leaking manholes, and disconnecting improper connections. This is enormously expensive work that takes years and hundreds of millions of dollars even for mid-sized utility systems.

There are several ways to find out:

• 1.Sewage Monitor — this site. Use the map to see reported events near your location, or search by ZIP code or city. Remember that events appear here days to weeks after they occur, and only events reported to EPA ECHO are visible.

• 2.Your local water or sewer utility. Most large utilities have emergency overflow notification systems — some post alerts on their website, some send automated calls to nearby residents, some post to social media. Find your utility and check their notifications or emergency contact number.

• 3.Your state environmental agency. Many states have public spill or incident databases. Search for "[your state] sewage spill reporting" or "[your state DEQ] spill notification."

• 4.Beach and water quality monitors. The EPA's BeachGuard system, Swim Guide app, and local health department websites often post swimming advisories that are triggered by nearby SSO events, even if the connection is not always made explicit.

• 5.Direct observation. Raw sewage smells strongly of hydrogen sulfide (rotten eggs) and has a distinctive brown-gray color. If you see discolored water flowing from a storm drain into a creek, or a manhole cover that appears wet or bubbling, contact your local utility emergency line.

Technically, both are types of sanitary sewer system failures, but they are classified differently for regulatory purposes:

A sanitary sewer overflow (SSO) in the traditional regulatory sense refers to sewage leaving the sewer system in a way that affects public areas, streets, or waterways — sewage coming out of manholes, discharging into storm drains, or reaching a creek. These events are reported to the state environmental agency and tracked in EPA ECHO.

A sanitary sewer backup (SSB), sometimes also called a "Category 3 SSO," refers specifically to sewage backing up into a building — through floor drains, toilets, or other plumbing connections — due to a problem in the sewer system upstream. The EPA's SSO reporting rule covers these, but historically they have been less consistently tracked.

From your perspective as a homeowner, the distinction matters mainly for insurance and liability. If your basement flooded with sewage because of a blockage or failure in the municipal main (not in your own lateral), you may have a claim against the utility. If the problem is in your own lateral pipe (the connection from your building to the municipal main), it is generally your responsibility.

Many utilities maintain 24/7 emergency response lines for sewage backups specifically. Call your utility before calling a plumber — if the problem is in the main, it is their responsibility to fix it, and their crew can often respond faster than a private plumber.

FOG stands for Fats, Oils, and Grease. It refers to the cooking byproducts — bacon grease, butter, cooking oil, food scraps high in fat — that enter the sewer system through kitchen drains.

Hot grease is a liquid and flows easily through pipes. But as it travels through the cooler temperatures of underground sewer pipes, it congeals. FOG doesn't just pass through — it sticks to pipe walls, accumulates layer by layer over time, and can eventually close off a pipe entirely. The resulting buildup is called a "grease plug" and is one of the most common causes of sewer blockages.

The EPA estimates that FOG blockages are responsible for approximately 50% of all sanitary sewer overflows — a staggering proportion. Restaurants and food service establishments are among the largest contributors; they typically handle enormous volumes of cooking oil and grease. Most jurisdictions require commercial food service operators to install and maintain grease interceptors (also called grease traps) that capture grease before it enters the sewer. However, these interceptors require regular maintenance — if a restaurant doesn't pump its grease trap regularly, it can overflow into the sewer system anyway.

Residential contributions are also significant. The "flushable wipes" problem compounds the FOG issue: wipes don't break down like toilet paper, and they combine with grease in the sewer to form massive obstructions called "fatbergs" — some of which have weighed hundreds of tons and required weeks to remove.

The fix for FOG is simple for individuals: let grease cool, pour it into a sealed container, and put it in the trash. Never pour cooking grease down the drain.

Not very — and you should treat them accordingly.

Reported gallon volumes for SSO events are self-estimates made by utility personnel at the time of the spill or shortly after. For a small, contained spill, an experienced employee can make a reasonable visual estimate based on pooled area and depth. For anything larger or messier, the estimation becomes increasingly speculative.

Several factors make accurate volume measurement difficult: — Sewage spreads across irregular terrain, making visual area estimates imprecise — Much of the overflow may go directly into storm drains or channels where it cannot be observed — Overflows at night or in remote locations may be discovered hours after they started — The utility may not know exactly when the overflow began — For pumping station failures during storms, there may be no way to directly measure what discharged

The result is that reported volumes tend to be rough order-of-magnitude estimates. Many utilities report suspiciously round numbers: 10,000 gallons, 100,000 gallons. These numbers should be read as "somewhere in this range" rather than precise measurements.

This matters when comparing events or utilities: a utility that consistently estimates carefully may look worse than a utility that systematically underestimates. It also matters when calculating totals — summed reported volumes for all US SSOs almost certainly underestimate the true total by a substantial margin.

The GAO's 2023 report on SSO data quality specifically identified volume reporting accuracy as one of the most significant weaknesses in the national data.

The short answer: scale, fragmentation, and politics.

The UK's real-time sewage overflow monitoring gained international attention after the Environment Act 2021 required water companies to install event duration monitors (EDMs) on all storm overflows. By 2023, near-total coverage was achieved and public platforms like Surfers Against Sewage's Sewage Map showed real-time overflow data. The resulting public outrage over widespread overflow events created significant political pressure on water companies.

The US faces a fundamentally different challenge:

Scale and fragmentation: The UK is served by a handful of large water companies that are regulated entities with defined geographic territories. The US has approximately 16,000 publicly owned sewer collection systems, operated by municipalities, counties, special districts, and regional authorities of wildly varying size and resources. There is no entity to mandate sensor installation across all of them the way the Environment Agency could mandate it for a handful of UK water companies.

Cost: Installing real-time monitors on every overflow point nationally would cost billions of dollars and require ongoing maintenance. The US hasn't funded basic pipe repairs; the political will for sensor networks doesn't exist yet.

Regulatory framework: The Clean Water Act and NPDES program create the framework for SSO reporting, but the EPA's ability to mandate specific monitoring technology is limited and contested. The eRule (electronic reporting rule) was a significant step toward better data, but it still relies on manual event reporting rather than automated sensor monitoring.

That said, progress is happening. Some forward-looking utilities — particularly those under consent decrees — are installing overflow detection sensors. USGS stream sensors provide indirect evidence of discharge events. And EPA is exploring real-time monitoring requirements in ongoing rulemaking.

The EPA's Electronic Reporting Rule (eRule) was finalized in 2015 and is being implemented in phases. Phase 2 of the rule extended electronic reporting requirements to NPDES-permitted wastewater facilities, including sewer collection systems that must report SSO events.

Before the eRule, SSO reporting was often done on paper or through state-specific systems that didn't consistently feed into the national EPA database. The requirement to report electronically through NetDMR (Net Discharge Monitoring Reports) or state-authorized equivalent systems means SSO data now flows much more reliably into the ICIS-NPDES database that powers ECHO.

Phase 2 requirements took effect in phases: — Large systems (serving populations over 10,000): requirements began phasing in starting in late 2022 — Medium systems: requirements rolling out through 2024–2025 — Small systems: additional time being provided, with full compliance expected by 2025–2026

What this means for Sewage Monitor's data:

If you see relatively sparse data for a particular state or region before 2023, it likely reflects pre-eRule underreporting rather than fewer actual overflows. The Phase 2 rollout is the single biggest driver of improving data quality in our database. We expect the volume of events in ECHO to increase significantly over 2025–2026 as more small systems come into compliance — not because there are more overflows, but because more of them are being captured.

States that were already aggressively enforcing reporting before the eRule (like Ohio, North Carolina, and several New England states) will see less change than states that relied heavily on paper reporting.

NPDES stands for National Pollutant Discharge Elimination System. It is the federal permitting program created by the Clean Water Act of 1972 that regulates what entities can discharge into the waters of the United States.

Under the NPDES program, any facility that discharges pollutants from a point source (a pipe, ditch, or other discrete conveyance) into a navigable water body must have a permit. For wastewater utilities, this means treatment plants have NPDES permits that specify exactly what they are allowed to discharge — and at what concentrations — after treating sewage. These permits set limits for parameters like biological oxygen demand (BOD), total suspended solids, ammonia, phosphorus, and fecal coliform bacteria.

Importantly, sewer collection systems — the pipes that carry sewage from buildings to treatment plants — do not have NPDES permits because they are not supposed to discharge at all. When an SSO occurs, sewage escapes this system unpermitted, which is a violation of the Clean Water Act by definition. This is why SSOs trigger reporting requirements and can result in penalties: every SSO is technically an illegal discharge.

NPDES permits are issued by state environmental agencies in states that have received EPA delegation (most states), or directly by EPA in states without delegation (Idaho, Massachusetts, New Hampshire, New Mexico, and some territories). The permits are public records and available through ECHO.

The primary legal responsibility for preventing and responding to sanitary sewer overflows rests with the utility that owns and operates the collection system — typically a city, county, regional authority, or special district. The utility holds the NPDES permit (or operates under a general permit) and is the responsible party when an SSO occurs.

The state environmental agency's role is regulatory: it issues and enforces permits, investigates complaints, and can levy fines or require corrective action plans when utilities have repeated or severe SSOs. In cases of egregious or chronic violations, EPA regional offices can also take direct enforcement action.

If sewage backed up into your property and caused damage, your legal recourse is typically against the utility. Liability varies significantly by state and municipality — some jurisdictions have sovereign immunity protections that limit utility liability, while others do not. Many utilities carry insurance for SSO-related property damage claims.

The city or county government is often involved but distinct from the utility — some cities operate their sewer systems as a city department, while others have created independent utility authorities. Calling your city councilperson about chronic SSOs is appropriate advocacy; your actual damage claim would go to the utility's insurance carrier or legal department.

Yes, they can be — but enforcement is inconsistent and penalties are often modest relative to the scale of violations.

The Clean Water Act authorizes civil penalties of up to $25,000 per day per violation for NPDES permit violations. SSOs, being unpermitted discharges, are technically violations. However, EPA and state regulators have generally not pursued maximum penalties for individual overflow events, particularly for utilities that promptly report, respond, and take corrective action.

Enforcement typically escalates when: — A utility has a pattern of chronic SSOs despite being aware of the cause — A utility fails to report SSOs as required — SSOs cause documented harm to public health or sensitive water bodies — A utility has received prior warnings or notices of violation without taking corrective action

In serious cases, EPA or state agencies can issue administrative orders, bring civil suits, or negotiate consent decrees that require major infrastructure investments. Some of the largest consent decrees in environmental law — requiring billions in sewer system investment — have come from SSO enforcement cases. Louisville, MSD (Louisville Metro Sewer District), Atlanta, and many other cities have operated under such decrees.

Individual citizens can also bring citizen suits under the Clean Water Act against utilities for Clean Water Act violations, subject to certain procedural requirements.

If you see raw sewage flowing in a street, from a manhole, or into a waterway, here's what to do:

• 1.Document it first. Take photos and videos. Note the exact location (street address or GPS coordinates), time, approximate volume, and where the sewage appears to be going. This documentation will be important for any regulatory or legal follow-up.

• 2.Call your local sewer utility. Most utilities have 24/7 emergency lines specifically for sewage overflows and backups. Search for "[your city/county] sewer emergency" to find the number. They are required to respond, contain the spill, and file an official report.

• 3.Call your state environmental agency. Your state DEQ or EPA-equivalent also accepts spill reports and may send an inspector, particularly if the overflow is large or has reached a waterway. Search for "[your state] DEQ spill report" for the right contact.

• 4.Contact EPA. If local or state authorities are unresponsive, EPA regional offices accept enforcement tips. You can submit a tip through EPA's online enforcement tip form or call your EPA regional office directly.

• 5.Notify local media if warranted. For significant events, local newspapers and TV news stations have environmental reporters who cover water quality issues. Public attention often accelerates utility response.

• 6.Stay away. Don't wade through sewage, don't let children or pets near it, and wash thoroughly if you have any contact with contaminated surfaces.

After reporting, follow up. Ask the utility for a copy of their incident report (this is a public record in most states). If you believe the overflow reached a waterway or caused an environmental impact, file a formal complaint with your state environmental agency so there is an official record.