Are you walking on water right now?
Thanks to lessons learned after the 1906 quake, SF has a dedicated firefighting water supply that's right under your feet.
Ever notice those big, beautiful, red brick circles at some SF intersections? No? Well put your phone away and look harder!
These giant, gorgeous red brick circles actually serve an important—and quite reassuring—purpose: they’re enormous underground water tanks, and they’re here to save your asphalt the next time things get too fire in this disco.
Let’s dive into our cisterns!
🔥 Born from the ashes
In 1906, the city had a full-blown meltdown—literally. When the earthquake hit, it caused water pipes to burst. Our water system basically ghosted. Hydrants ran dry and The City went up in flames. The devastation must’ve been unimaginable.
However, a few pockets of SF were lucky because some dusty old cisterns—basic but dependable—stepped up and saved the day.
So, in 1908, the city invested in the ultimate backup plan: more cisterns. 170+ of them. Installed under intersections all across town like the Beyoncé of emergency preparedness—ready for anything.
🚒 Wait, WTF is a cistern?
Each cistern is basically a huge underground tank, holding up to 200,000 gallons of water. They are filled to the brim, ready and wading. If the Big One hits and the hydrants flop again, the fire department can just lift the lid and hook up the hose.
🧱 Where are these so-called cisterns?
Check out this map via SF Fire. You can also look for two things at the street level. First, if you find a big red brick circle in the middle of intersection, there is a cistern directly underneath it! Also, keep an eye out for hydrants with green tops—that means there is a cistern underground there even if it’s lost its signature street level brick circle (which happens when a bad contractor repaves the road and does not replace the bricks).
TLDR: SF will continue its goodly weird legacy
San Francisco’s cisterns are the quiet queens of public safety. They don’t brag! They just lie there—moist, massive, and waiting to save your butt if disaster strikes.
So, the next time you strut across a red-brick ring in the street, give it a nod. You just stepped over a century old icon, waiting patiently to come to our rescue.