Sump pumps and basement flooding in Portland

Before buying equipment, work out the source:

A sump pump does nothing for a sewer backup, and a backwater valve does nothing for groundwater, so match the fix to the source.

HomeGuide's 2026 sump pump guide gives national figures: $600 to $2,500 installed, with a $1,600 average. The pump itself runs $100 to $400 for a pedestal unit and $100 to $800 for a submersible, and a battery backup pump costs $150 to $800 on average. If the concrete floor has to be cut or jackhammered for a new pit, installation can reach $2,500 to $5,000, and a new interior drainage system $4,000 to $12,000. Replacing a pump in an existing basin averages $400 to $700. HomeGuide puts lifespans at 10 to 30 years for pedestal pumps and 5 to 20 years for submersibles.

Portland's plumbing permit fee schedule lists ejectors and sumps as a $63 item, so ask your contractor whether your installation needs a permit and where the pump will discharge. A pump that sends water back against the foundation, or onto a neighbor's lot, just recirculates the problem.

Portland Environmental Services' page on what to do after a sewer backup says to call a plumber first to find the cause, and describes a sewer backflow prevention device as a one-way valve in the home's drain line that lets wastewater out and swings shut to keep sewage from flowing back in. The city's Sewer Backup Prevention Program works like this:

• Residents of combined sewer areas subject to basement flooding may apply; Environmental Services can tell you if your home qualifies.
• After approval, the resident hires a plumbing contractor.
• The resident pays the first $100, the city pays the next $1,500, and the resident pays anything above that. Installation typically costs around $1,600.
• The device belongs to the resident, who maintains it, and the owner is responsible for future backups at the address.

For a sewer emergency, Portland Environmental Services lists 503-823-1700, which it says is answered at any hour. In Gresham, the city's sewer backups page says properties lower than the nearest street manhole are typically at greater risk without a backwater valve, and that the Oregon State Plumbing Code requires one at applicable properties. If roots or a broken lateral caused the backup, fix that first; see our tree roots guide.

Portland's downspout disconnection page sets safety rules for sending roof water into the yard instead of the sewer:

• Discharge at least 6 feet from a basement, or 2 feet from a crawl space or slab foundation.
• Keep the end at least 5 feet from a neighbor's property line and 3 feet from a public sidewalk.
• Do not disconnect on slopes greater than 10 percent, or within 10 feet of a retaining wall.
• The soaking area must be at least 10 percent of the roof area draining to it.

No permit is needed for an extension and splash block, but a drywell or soakage trench has its own permit rules.

Portland's floodplain guidance says most homeowners insurance does not cover flood damage, that flood insurance is available through most local agents under the National Flood Insurance Program, and that you should check whether you have sewer backup coverage. Properties in Portland's 100-year floodplain automatically get a 25 percent flood insurance discount because the city participates in FEMA's Community Rating System. The city also advises elevating belongings and mechanical systems and not using a flood-prone basement for living space.

We are an independent guide, not a contractor. To reach a plumber, call one of the licensed contractors listed on this page or see all listed contractors. Questions about this guide: email us. We do not take service requests.