What is Sewer Backup Insurance?

By Jon Merwin, Founder and CEO, Licensed Insurance Advisor

Short answer: sewer backup insurance is an endorsement you add to a homeowners, condo or renters policy. It pays for damage caused when water or sewage comes up through your drains, toilets or floor drains, or when your sump can’t keep up, up to the limit shown on your policy. Without it, most homeowners policies won’t pay for that kind of loss, and a flood policy only steps in when an actual flood caused the backup. Because the wording differs from one insurer to the next, the details of your own endorsement matter more than the name.

Portsmouth Atlantic Insurance is a family-owned independent agency in Portsmouth, New Hampshire. We place home, condo and renters coverage across New England through 40+ carriers, and our clients have left 1,000+ Google reviews and over 2,000 testimonials. Our team brings 200+ years of combined experience, and backed-up basements are one of the claims we hear about every spring. Below we explain what the coverage does, where its edges are, and how to decide whether your home needs it.

Why a standard homeowners policy leaves this out

Most homeowners policies cover the house on an open-peril basis, which means damage is covered unless an exclusion applies. Water is where many of those exclusions live. The usual water exclusion removes flood, surface water and tidal water, water below the surface of the ground, and water that backs up through sewers or drains or overflows from a sump, sump pump or related equipment.

The New Hampshire Insurance Department says the same thing in its homeowners consumer guide: the policy’s flood exclusion takes in water that backs up from sewers, drains or sump pumps, along with water seeping through basement walls and floors. The department adds that most policies exclude backup damage and that many companies sell the coverage as an endorsement at an added cost.

One reason insurers handle it this way is that backup losses tend to cluster. When a heavy storm overloads a town’s sewer system, dozens of basements on the same street can fill at once. Writing it as a separate, limited coverage lets each carrier decide how much of that risk it is willing to take on.

What sewer backup coverage usually pays for

Endorsement names vary: water backup, sewer and drain backup, water backup and sump discharge or overflow. The Michigan Department of Insurance and Financial Services explains in its consumer guide to water and sewer backup coverage that the coverage typically responds to two events:

• Backup through a sewer or drain. Water or sewage pushed back into the house through a floor drain, toilet, tub or basement fixture because the line it should flow into is blocked or overloaded.
• Overflow from a sump. Water rising out of the sump pit and into the basement, including when the pump breaks down mechanically.

When one of those events happens, the endorsement can pay for damage to the building, such as drywall, flooring, carpet, trim, cabinets and a furnace or water heater ruined by the water, and for damaged belongings stored or used in the basement. Depending on the wording, cleanup and drying may be part of the claim, and if the home can’t be lived in while repairs are made, loss of use coverage may help with the extra living costs.

What it usually doesn’t pay for

• The pump itself. Repairing or replacing a burned-out sump pump is generally not covered. The coverage is for the water damage the failure causes.
• The sewer pipe. Fixing a cracked, root-filled or collapsed sewer line is a separate question. That is the job of service line coverage, another optional add-on.
• Flooding. Most backup endorsements still exclude backups caused by a flood, surface water or storm surge. Those losses belong to a flood policy.
• Groundwater seepage. Water that works its way through foundation walls or up through the slab is usually excluded everywhere.
• Neglect and wear. A pump that was never maintained, or a backup traced to something an owner did, can lead to a denial. Many endorsements state that the loss must not be caused by the insured’s negligence.

Limits and deductibles

Backup coverage almost always carries its own limit, separate from your dwelling limit, and the endorsement doesn’t raise any other limit on the policy. The Michigan guide notes insurers may set it as a specific amount or as a percentage of the dwelling coverage. Some endorsements also carry their own deductible. The limit is the number to look at first, because a finished basement can hold far more value than people expect. An endorsement may be available with higher limits from some carriers; the limits vary by insurer and by state, so we compare them side by side when we shop a home.

Sewer backup vs. flood vs. water damage

Three kinds of water losses get confused all the time, and each is handled by a different part of your insurance:

• Sudden water damage from inside the house. A burst pipe, a split washing machine hose or a failed toilet supply line. A standard homeowners policy usually covers the resulting damage, because the water came from your own plumbing suddenly and accidentally.
• Backup and sump overflow. Water coming in through the drains or rising out of the sump because the system it drains into can’t take it. Excluded on a standard policy; covered by the backup endorsement up to its limit.
• Flood. Water from outside the house that covers normally dry land, such as an overflowing river, a coastal surge or heavy runoff across the neighborhood. Excluded on homeowners policies; covered by a separate flood insurance policy.

The Insurance Information Institute’s flood insurance guide points out that homeowners, condo and renters policies don’t cover flooding as a rule, and suggests a flood policy for any home that could be flooded by melting snow, an overflowing creek or pond, or runoff from a steep hill. It also notes the National Flood Insurance Program has a 30-day waiting period before a new policy takes effect, so buying one when the forecast turns bad is usually too late.

When flood insurance covers a backup

Here is the key distinction. The Standard Flood Insurance Policy, which is printed in federal regulations and available on Cornell Law School’s Legal Information Institute, excludes water that backs up through sewers or drains, overflows from a sump or seeps through the property, unless there is a flood in the area and the flood is the proximate cause. FEMA’s flood coverage overview for agents puts it simply: sewer backup damage is covered by flood insurance only if it directly results from flooding.

In practice that means a backup caused by a clogged main on a dry day is a backup endorsement question, while a backup that happens because the river has spilled into the streets is a flood policy question. Since many backup endorsements exclude backups caused by flooding, owners in a flood-prone area often need both. If you’re not sure where your home stands, our flood zone lookup is a good first step. Keep in mind that NFIP coverage for basements is limited to a list of items, which we explain in our post on basement flooding and insurance.

Backup scenarios at a glance

Typical outcomes under widely used policy forms. Endorsement wording, state rules and the facts of the loss always decide the result.

Situation	How coverage often works
The town sewer main clogs and sewage comes up through the basement floor drain	Excluded on a standard policy; the backup endorsement may pay up to its limit
The sump pump motor fails during spring thaw and the basement takes on water	The endorsement may pay for the water damage; the pump itself usually isn’t covered
A nor’easter knocks out power and the sump stops running	Depends on the endorsement; some include overflow caused by a power failure and some don’t
A river overflows into the neighborhood and water pushes up through the drains	A flood policy question; the NFIP form covers backup when a flood in the area caused it
Groundwater seeps through the foundation walls after weeks of rain	Usually not covered by a homeowners policy, a backup endorsement or an NFIP policy
A toilet supply line bursts and soaks the floor below	Usually covered as sudden water damage under the standard policy, not a backup
Tree roots crush the sewer line between the house and the street	The pipe repair may fall under service line coverage; resulting backup damage under the backup endorsement
A slow drip under a sink rots the cabinet over many months	Generally excluded as long-term leakage or wear
Grease or wipes the owner put down the drain cause the clog	Can be disputed; many endorsements exclude loss caused by the insured’s negligence

Why backups are common in New England

Sewer backups happen everywhere, but several things about the way New England was built make them more likely here.

Older sewer systems that carry stormwater too

Many of our older cities were sewered long before anyone separated rainwater from the wastewater leaving homes. The U.S. Environmental Protection Agency’s combined sewer overflow overview explains that in a combined system, wastewater and stormwater flow through the same pipes, and in wet weather the combined flow can overwhelm the system. EPA describes combined sewer overflows as a concern for roughly 700 communities across the country.

The Massachusetts Department of Environmental Protection says older cities across the state may still have combined systems, that heavy rain or snowmelt can overload them, and that without overflow points the mix would back up into homes, businesses and streets. It lists Boston, New Bedford, Worcester and Springfield among the communities with permitted overflows. MassDEP also notes that groundwater, rainwater and snowmelt leaking into separate sewers through cracks or improper connections can cause backups into homes during big storms. Even a home on a modern separate system can see a backup when the lines are overloaded.

Spring thaw, nor’easters and summer downpours

Our wettest stretches tend to stack up: a snowpack melting on top of heavy March rain, a stalled nor’easter in the fall, or a summer thunderstorm that drops a lot of water in a short time. Each one raises groundwater, fills sumps and pushes sewers toward capacity. Storms that bring down power lines can stop a sump pump at the worst possible moment. Our posts on rain damage and leaks and snow and ice damage in the Northeast cover the other water claims those storms bring.

Old houses, deep basements and finished lower levels

Much of the housing stock from Portsmouth to Portland to the North Shore is decades or a century old. Many homes sit on fieldstone or block foundations, with floor drains, original cast iron or clay sewer laterals and basement fixtures that sit below street level. Over the years many of those basements have become family rooms, guest suites, home gyms and laundry rooms. That raises what’s at stake in a backup and is the main reason a low endorsement limit can fall short. Our guide to older and historic home insurance in New Hampshire covers other issues insurers look at on older houses.

Septic systems and private lines

Plenty of homes in rural New Hampshire, Maine and Vermont have a septic system instead of town sewer. Wastewater can still back up into the house when a tank or leach field fails or the ground is saturated. Whether a backup endorsement responds depends on its wording and the cause, and failure of the septic system itself is usually a maintenance issue rather than an insured loss. Ask how your policy treats it before you need it.

Who it’s for: owners, condo owners and renters

• Homeowners. Anyone with a basement, a sump pump, below-grade plumbing or a finished lower level should at least look at the endorsement. Our home insurance page and the guides for New Hampshire and Massachusetts homeowners explain the rest of the policy.
• Condo owners. A garden-level or ground-floor unit can take a backup even when the building’s master policy handles the common pipes. A condo (HO-6) policy may offer its own backup endorsement for your walls, floors and belongings; see condo vs. homeowners insurance.
• Renters. The landlord’s policy doesn’t cover a tenant’s things. Backup coverage may be available on a renters insurance policy for belongings in a basement apartment or storage area.

How much coverage makes sense

There’s no single right limit. A useful way to think about it is to walk the basement and picture the floor under a few inches of dirty water. Add up what it would take to replace the flooring, the lower part of the walls, built-ins, the furnace, boiler or water heater, the washer and dryer, and everything stored down there. A bare utility basement and a finished family room with a home office need very different limits.

Then read how your current endorsement is written. An endorsement may be available with a higher limit, and some carriers offer broader wording, for example covering backup that starts in the town’s system as well as inside the house, or including overflow from a power failure. Limits and wording vary, which is exactly why it helps to compare them.

Lowering the odds of a backup

• Ask a licensed plumber about a backwater valve. A backwater (or backflow) valve on the main sewer line lets wastewater out and closes when the sewer pushes back. Installing one usually takes a permit. Your plumber can tell you whether one fits your house.
• Test the sump pump before the wet season. Pour water into the pit and make sure the float lifts and the pump runs. Clear the discharge line and keep it pointed away from the foundation.
• Plan for power outages. A battery backup pump, a water-powered backup where allowed, or a generator can keep the sump going when the lines are down.
• Have the sewer lateral inspected. A camera inspection can find roots, sags and cracks in an older clay or cast iron line before they cause a clog, especially when buying an older home.
• Keep grease, wipes and other debris out of the drains. They’re a common cause of clogs in the line you own.
• Check where your downspouts go. In some older homes they still tie into the sewer. Many sewer departments discourage or prohibit that, and redirecting them to the yard keeps roof water out of the system.
• Raise what you store. Put boxes on shelves, keep furnaces and water heaters on raised pads where possible, and avoid storing valuables and important papers on a basement floor.

For more prevention ideas, see our guide to preventing water damage to your home.

If your basement backs up

• Stay safe. Keep out of standing water if outlets or appliances could be live, and keep children and pets away. Wear gloves and boots around sewage.
• Stop the source if you can. Hold off on running water, flushing or doing laundry until the line is cleared, and call a plumber or your town’s public works department.
• Document everything. Take photos and notes before cleanup starts, and keep damaged items or samples until the adjuster says otherwise.
• Limit further damage. Most policies require you to take reasonable steps to prevent more damage. A professional water and sewage cleanup company can dry and sanitize the space; keep every receipt.
• Report it promptly. Give us a ring; we can walk you through reporting it to the carrier and sort out which part of your coverage applies. Mold that follows a backup is often limited, so speed matters; see our post on mold and homeowners insurance.

Curious how a backup claim could affect you later? Read how long a home insurance claim takes, how long claims stay on your record and the pros and cons of filing a claim.

Questions to ask about your backup coverage

• Does my policy include water or sewer backup coverage, and what is the limit?
• Is there a separate deductible for backup claims?
• Does it cover overflow from the sump when the pump breaks down? What about a power failure?
• Does it cover water that backs up from the town sewer, or only water that starts inside my plumbing?
• Are finished basement walls, floors and contents treated the same as the rest of the house?
• Does loss of use apply if a backup makes the home unlivable?
• Do I also need flood insurance, and how would the two policies work together?

We’re glad to answer any of these for you. Our guide to the declarations page shows where endorsements are listed, our overview of homeowners coverage explains the other parts of the policy, and a policy review lets us check the backup, service line and equipment breakdown add-ons together.

Not sure if backup coverage is already on your policy? Email us your declarations page, and we’ll point out the endorsement and its limit.

Frequently asked questions

Does homeowners insurance cover sewer backup?

Usually not on its own. A standard homeowners policy excludes water that backs up through sewers or drains or overflows from a sump. Many insurers offer a water or sewer backup endorsement that adds the coverage back, up to a separate limit, so check your declarations page to see whether you have it.

What does sewer backup insurance cover?

It generally covers direct damage to your home and belongings when water or sewage backs up through a sewer or drain or overflows from a sump, including when the sump pump breaks down. It usually doesn’t pay to replace the pump or repair the sewer line, and it typically excludes backups caused by a flood.

Does flood insurance cover sewer backup?

Only in some cases. The federal flood policy covers a sewer or drain backup or sump overflow when there is a flood in the area and the flood is the proximate cause. A backup from a clogged line or failed pump with no flood around it isn’t a flood claim, which is why many owners in flood-prone areas carry both coverages.

Is damage from a failed sump pump covered?

With a backup endorsement that includes sump overflow, the water damage from a failed pump may be covered up to the endorsement limit. The pump itself usually isn’t. Overflow caused by a power outage depends on the wording, so ask whether your endorsement includes it.

How much sewer backup coverage do I need?

It depends on what’s in your basement. A finished lower level with flooring, built-ins, mechanicals and stored belongings needs much more than an unfinished utility space. Estimate what it would take to repair and replace everything below grade, then compare that with the limit on your endorsement.

Can condo owners and renters get sewer backup coverage?

Often, yes. Many condo (HO-6) and renters policies can add a backup endorsement for the owner’s or tenant’s own walls, floors and belongings. Availability and limits vary by carrier. For a look at what your own policy says, reach us at (603) 431-4020.

Sources

• U.S. Environmental Protection Agency: Combined Sewer Overflow Basics
• Cornell Law School Legal Information Institute: 44 CFR Appendix A(2) to Part 61, Standard Flood Insurance Policy (General Property Form)
• FEMA National Flood Insurance Program (agents site): Types of Coverage
• Michigan Department of Insurance and Financial Services: Water and Sewer Backup Coverage (FIS-PUB 6380)
• Insurance Information Institute: Do I need flood insurance for my home?
• New Hampshire Insurance Department: Homeowners and Renters Insurance consumer page (insurance.nh.gov)
• Massachusetts Department of Environmental Protection: Sanitary Sewer Systems and Combined Sewer Overflows (mass.gov)

Already a client and want to add backup coverage or change a limit? Visit the Service Center or send a policy change request.

This guide shares general information on how home, condo, renters and flood policies commonly handle sewer and water backup. It isn’t legal advice and makes no offer or promise of coverage. How any claim is settled comes down to the exact policy wording and endorsements, each carrier’s rules, the law in your state and what actually happened. The policy itself controls, and we’ll gladly help you go through yours.