Backwater Valves in Milwaukee Basements: Who Needs One
Updated 2026-10 · Milwaukee, WI
What a backwater valve does
It is a one-way flap or gate fitted into the building drain. Wastewater flows out normally. When the sewer surcharges and tries to push back into the house, the valve closes and keeps that water out of the floor drain and basement fixtures. It protects against one thing, the sewer backing up. It does nothing about groundwater through walls or rain coming in at window wells.
Who it actually helps
A basement that backs up in big storms with a sound lateral
If a camera inspection shows a clean, intact lateral and water still comes up at the floor drain in heavy rain, the sewer is surcharging and a valve is the direct answer.
Homes in the combined sewer area
Near downtown and in much of Shorewood, storm water and sewage share one pipe by design. MMSD puts the combined area at about six percent of its service area, all of it in Milwaukee and Shorewood. Basements there are exposed in a way others are not.
Not a fix for a broken lateral
If the backup is caused by roots or a collapsed section in your own lateral, a valve will not help, because the blockage is downstream of it. Repair comes first.
What installation involves
In an older Milwaukee basement, installing a valve usually means cutting the concrete floor, digging to the building drain, setting the valve so it can be reached for cleaning, and patching the floor with an access cover. It is quoted as a project rather than a part, and the price swings on depth, how the drain is laid out, and whether the floor drain and any basement fixtures can sit upstream of the valve. That last point matters in Polish flats and other homes with a basement unit, where fixtures can sit very low.
Living with one
While the valve is closed, nothing you run in the house can leave either. During a big storm, the household stops using water: no laundry, no showers, no flushing. Valves need occasional cleaning and checking, because a flap held open by debris protects nothing. Ask the installer how to inspect it and how often.
Before you pay for one
- Get the lateral camera-inspected, and keep the recording.
- Ask whether clear water (foundation drains, downspouts) is getting into your sanitary line.
- Ask MMSD whether Pipe Check incentives apply to your lateral or clear-water work, and whether the company is an approved contractor.
- Ask about the permit and who pulls it.
- Check whether your insurance policy has a sewer backup rider.
Floor drain backing up when it rains? Call and ask about a camera inspection before deciding on a valve.
Where to go next
Common questions
Is a backwater valve the same as a check valve on a sump pump?
No. A sump pump check valve stops pumped water falling back into the pit. A backwater valve sits on the sewer drain and stops sewage coming in.
Does MMSD pay for backwater valves?
MMSD’s Pipe Check programme covers sewer lateral repair and clear-water disconnection through approved contractors. Ask MMSD directly what is currently eligible.
Will a valve make my basement unusable in a storm?
Only for using water. While it is closed, avoid sending water down any drain, because it cannot leave the house until the sewer drops.