Sewer backup is the classic "I thought I was covered" claim. A standard homeowners policy excludes water that backs up through sewers, drains, or a failed sump pump — even though it's one of the most common and messiest basement losses. The fix is a specific, inexpensive endorsement most homeowners don't know to ask for.
The short answer
No — not by default. Standard homeowners specifically excludes damage from water that backs up through sewers or drains and from sump-pump failure. To be covered you add a water-backup endorsement (sometimes called sewer/drain backup or sump-pump coverage), typically $50–$100/year for $5,000–$25,000 of coverage. It's separate from both regular water damage and flood.
Why it's excluded — and what the endorsement adds
Insurers carve backup out of the base policy because it's frequent and tied to aging municipal sewers and sump pumps homeowners don't maintain. The water-backup endorsement covers: sewage or water that backs up through drains, overflow from a sump pump or sump-pump failure, and the resulting cleanup and property damage. Some insurers bundle it with service-line coverage (the buried pipe from the street to your home).
Sewer backup vs. flood vs. water damage
Three different things, three different rules: sudden internal water (a burst pipe) is covered by base homeowners (see water damage); flood (rising water from outside) needs a separate flood policy; sewer/drain backup needs the water-backup endorsement. A heavy storm that overwhelms the city sewer and pushes water up your basement drain is backup, not flood — and only the endorsement covers it.
How much coverage to buy
Base endorsements often start at $5,000, which a finished basement blows through fast. If you have a finished basement, sump pump, or below-grade utilities, step up to $25,000+ — it's usually only a few more dollars a year. The coverage calculator flags backup and service-line coverage together.
Reduce the risk (and keep the claim clean)
- Install a backwater valve and maintain your sump pump (a battery backup helps).
- Keep the endorsement — the coverage only exists if you added it before the loss.
- After a backup: photograph everything, stop using drains, and get professional cleanup (sewage is a health hazard). Keep receipts.
Bottom line: sewer and sump-pump backup isn't in a standard policy — add a water-backup endorsement (~$50–100/yr) and buy enough limit for a finished basement. It's separate from both flood and ordinary water damage.
Frequently asked questions
Does homeowners insurance cover sewer backup?
Not by default — it's excluded. A water-backup endorsement (about $50–100/year) adds coverage for sewer/drain backup and sump-pump failure, typically $5,000–$25,000.
What is a water-backup endorsement?
An add-on that covers damage from water backing up through sewers or drains and from sump-pump overflow or failure — losses the base homeowners policy excludes.
Is sewer backup the same as flood?
No. Flood is rising water from outside and needs a separate flood policy. Sewer backup is water pushing up through your drains and needs the water-backup endorsement — even when a storm caused it.
How much does sewer backup coverage cost?
Usually $50–$100 per year for $5,000–$25,000 of coverage. Homes with finished basements should buy the higher limits, which add only a little.
Does homeowners insurance cover a failed sump pump?
Only if you have a water-backup/sump-pump endorsement. Damage from sump-pump failure is excluded from the base policy.