A recurring thief has been stealing sewer vent grates from Bernal Heights sidewalks since April 2026, with city policy placing the $40 replacement cost on homeowners despite police acknowledgment of over 400 such thefts citywide.

On Mullen Avenue in Bernal Heights, the 4-by-4-inch hole in the sidewalk appeared again in May. It was the third time since April that the sewer vent grate had vanished from the same spot. Each time, security cameras captured the same routine: a slim figure in a beanie, headlamp on, prying loose the metal cover and slipping it into a grocery cart before moving to the next target.

The mystery thief has hit multiple streets across Bernal Heights in 2026—Mullen, Brewster, Montcalm, and Macedonia—according to resident reports. The citywide numbers are stark: over 400 sidewalk utility covers reported stolen in the past two years, the San Francisco Police Department said in a February 2025 news release. But the local Ingleside Police Station told residents it hasn’t identified a trend, even as the department confirmed “active and open investigations” into whether the incidents form a series.

What makes the Bernal Heights spree different from typical scrap‑metal theft is the economics. The grates are worth next to nothing—recyclers report the mixed steel yields just three to five cents per pound, meaning about 32 grates to make a dollar. Yet the costs fall squarely on homeowners. Under Section 706 of the San Francisco Public Works Code, property owners are responsible for sidewalk maintenance, including missing sewer vent covers. The city can perform repairs after 30 days and place a lien on the property for the cost, estimated at $40 per unit by Public Works (though one resident found replacements for about $10).

“I just want to know who’s doing this,” resident Karen Cook told Mission Local. “When things are getting stolen from you, it just feels like a constant violation.”

The 311 data that might reveal the scope is incomplete. Bernal Heights logged 345 service requests in the past week, but there’s no distinct category for sewer grate thefts, making it impossible to count how many have been reported or track response times. The city’s public dataset doesn’t filter by the specific issue, leaving residents to document the pattern themselves.

Some homeowners have tried fighting back. Kevin Stamm, a former general contractor, reinforced his grates with security measures. One resident reported using tamper‑resistant screws, only to watch on camera as the thief removed the special screw, took the grate, and screwed it back in.

For now, the pattern continues: a hole appears, a homeowner pays to fix it, and weeks later, the mystery man returns for more.