Cohasset · Sump Pumps
Water seeping into a Cohasset basement after heavy rain or a coastal storm? Learn what the town's flood mapping shows, then call or send a request to reach an independent plumber for sump work.
Cohasset, Massachusetts
Cohasset sits right on the water, and the town has studied in detail how the ocean gets in. A February 2025 memo from the Metropolitan Area Planning Council calls flooding, both inland and coastal, a pressing climate hazard for the town and notes that Cohasset has identified 166 coastal flooding pathways. Low ground around Cohasset Cove and the James Brook watershed, including Summer Street, has been the focus of state-funded flood design work.
For a homeowner, that means groundwater can rise and storm water can pool against a foundation even when the sea doesn't reach the house. Older stone and block foundations, common in a town where about 28% of homes date to 1939 or earlier, let that water seep through. A sump pump in a pit at the low point of the basement collects it and pushes it outside.
Tell us what's going on and you'll be connected with an independent plumber who installs and repairs sump pumps in Cohasset. We're a referral site; the plumber assesses the basement and gives you the plan and price.
Water that appears along the walls or floor cracks after storms means groundwater is pressing in, and it will keep doing so.
White, chalky deposits on stone or block walls are minerals left behind by water moving through the foundation.
A pump that cycles nonstop, hums without moving water, or is many years old is close to failing, often during the storm it's needed for.
Steady dampness shows up as mildew smells, rust on the water heater base, and corrosion on tools and appliances stored below.
Local knowledge
Town and regional findings that explain where Cohasset basements are most at risk.
166 Flood Pathways
The 2025 MAPC memo reports that the town has identified 166 coastal flooding pathways. If your home is near one, plan for more than one pump, a battery backup, and a discharge that carries water away from the low side of the lot.
Cove And Summer Street
The town's coastal resilience page, archived in February 2026, describes state CZM grants for wastewater flood protection and for James Brook watershed flood pathway design aimed at Cohasset Cove and Summer Street. Homes in that area should treat sump capacity and backup power as basics.
FEMA Flood Maps
FEMA issued its letter of final determination on Cohasset's updated flood insurance rate maps on November 14, 2016, starting a 120-day period before they took effect, per the town's archived flood map page. Check where your property falls before deciding how much pumping capacity to install.
Right now
Stay safe first, then slow the water down.
If water has reached outlets, cords, the electrical panel, or a gas appliance, keep out of the basement and call 911 or National Grid. Don't wade in to unplug anything.
If you have a pump and it's safe to reach, see whether it's plugged in and whether the float moves freely. Debris around the float is a common reason pumps stop.
Once the rain eases, make sure downspouts empty well away from the foundation so roof water doesn't add to the problem.
Lift boxes, electronics, and anything stored on the floor onto shelves before the next storm.
What to expect
For a new installation, the plumber picks the low spot in the basement, cuts and digs the pit, sets a liner, and installs the pump with a check valve and a discharge pipe through the wall. In fieldstone or older foundations, they may also discuss perimeter drains that route water to the pit. Ask about a battery backup or a second pump, since coastal storms in Cohasset can bring both heavy rain and power outages.
Where the discharge ends up matters. Water from a sump belongs outside, aimed away from the house and neighbors, not into a laundry sink or floor drain that leads to the sewer. The town's sewer plant is sized for a maximum daily flow of 450,000 gallons, according to the Sewer Department page archived in February 2026, and groundwater pumped into it during storms takes up capacity meant for wastewater. If you're unsure where your current pump drains, ask the Sewer Commission about the rules and the plumber about rerouting.
Hire smart
Plumbing and gas fitting in Massachusetts require a license from the Board of State Examiners of Plumbers and Gas Fitters, and most plumbing work needs a permit from the town's plumbing inspector.
Look up the plumber's Massachusetts license on the state's occupational license search before you agree to the work.
Ask what backup the plumber recommends for your house and how long it would keep the pump running during an outage.
Make sure the discharge plan sends water outside and away from your foundation and your neighbors' property.
Ask whether any part of the job, such as electrical work or plumbing connections, needs a permit from Building & Inspections.
Costs
The price depends on whether a pit already exists, how hard the floor and foundation are to dig through, the pump size and type, any battery or second pump, and how far the discharge has to run. Fieldstone foundations and ledge can add labor, and adding perimeter drains is a bigger project.
Ask for a written estimate that lists the pump, backup, pit work, discharge piping, and any electrical work. If you're near the cove or harbor, ask what capacity the plumber is planning for and why, so you can compare quotes on the same basis.
More help in Cohasset
Every page below is written for Cohasset homes. Or start from the Cohasset plumbing guide.
Learning Center
A short list of the right questions tells you more about a plumber than any ad. Use these on the phone, during the site visit, and before you sign off on an estimate.
Read the guide
Massachusetts has some of the clearest plumbing rules in the country. Here is how to use them to pick a plumber with confidence, whether the job is a dripping shutoff or a full repipe.
Read the guideQuestions
Still not sure? Send a short request and a local pro can answer the specifics.
Check FEMA's flood insurance rate maps for your address; Cohasset's updated maps followed a final determination issued November 14, 2016. Even outside a mapped zone, groundwater and heavy rain can wet a basement, and the town has identified 166 coastal flooding pathways.
It shouldn't. Groundwater sent into the sewer takes up treatment plant capacity and can contribute to backups during storms. Ask the Sewer Commission about the town's rules, and have a plumber route the discharge outside.
It's worth serious thought. Storms that bring flooding often knock out power too, and a pump without backup stops when you need it most. A plumber can size a backup to your basement and pump.
The town has received state Coastal Zone Management grants to study and design flood protection for wastewater facilities and the James Brook watershed, and held harbor climate resilience forums in 2022 and a public forum on harbor flooding concepts on May 1, 2025. Those projects protect town assets; your basement still needs its own protection.
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