by Scott Kildall

Visualizing San Francisco’s water infrastructure

San Francisco has an urban circulatory system that lives underneath our feet. It provides water to our homes, delivers a reliable supply to fire hydrants, removes waste from our toilets, and ultimately purifies it and directs it into the bay and ocean. Most of us don’t think about this amazing system because we don’t have to—it simply works.

But I like to think about how water works in San Francisco. I am fascinated by urban infrastructure, from fire hydrants to electrical access panels to phone cable boxes—the stuff you see when you are walking through the physical space of a city. Whenever city employees are working in a manhole, I stop and peer inside to see what is down there. They may not appreciate this, but I can’t help myself. I’ve even done my share of urban spelunking, adventuring through storm drains and other places I don’t belong. I’m just curious. So last summer I started work on Water Works, an art project and 3D data visualization through which I explored how water moves through the bowels of the city.


The project was part of a Creative Code Fellowship, supported by Stamen Design, Autodesk, and Gray Area—a design studio, a 3D software corporation, and a nonprofit arts organization, respectively. At these three organizations, I had desk space, state-of-the-art fabrication tools, and mentoring to help me create large-scale 3D-printed sculptures, each paired with an interactive web map at

As an artist, I’ve worked with sculpture and software code for many years, but I’m only now learning to fully integrate the two media, using digital fabrication tools such as laser cutters, 3D printers, and other computer-controlled machines. These machines can use 3D renderings or 2D image files to create objects such as plastic 3D models, perfectly cut wood stencils, and finely milled aluminum parts. Since they remove traditional shop-craft techniques such as table sawing and routing from making sculpture, the artistry is in the concept, the ferreting out and assembling the data, and the ways that data can be manipulated and transformed into something tangible. That programming is an art is a fact often overlooked, and it’s never truer than when it is in service of a project like Water Works.

It’s a new frontier of artistic possibility. As far as I know, I’m the first person to mine city data and write software algorithms to generate 3D-printed maps. My directive for the project was to somehow make visible what is invisible; to turn virtual data into physical reality.

2Screen Shot 2014-08-12 at 10.09.19 PM



The first step was to get permission from San Francisco to access its sewer data. The dataset was both incredible and incredibly complex. I discovered that the city had about 30,000 nodes (underground chambers with manholes) with 30,000 connections (pipes). But it quickly became clear that the information I needed, like all data, was messy and needed a lot of pruning, trimming and reworking. From previous data projects, I knew you have to work with the data you can get, though, not the data you think someone should have and wish you could get. So I spent many hours writing custom software algorithms to clean up the data. It was tedious, but oddly satisfying.

Then I began a deep survey of San Francisco’s water infrastructure. In the first month of the Water Works project, this involved endless research and culling, chasing leads and running into dead ends. I called myself a “water detective,” much like Jake Gittes in Chinatown. I soon learned that the city has three separate sets of pipes that comprise the water infrastructure: a potable water system, supplied by Hetch Hetchy; a combined stormwater and wastewater sewer system; and the Auxiliary Water Supply System (AWSS), which is a separate infrastructure used only for emergency fire fighting and which is fed from the Twin Peaks Reservoir. The AWSS was built in the years immediately following the 1906 earthquake, when many of the water mains collapsed and most of the city proper was destroyed by fires.

My nights were consumed with the search for water data, and I eventually found a great lead: the brick circles I’d long been puzzled over in the middle of intersections throughout the city. It turns out these markings are used to indicate the locations of underground cisterns, tanks of water used exclusively for emergency fire fighting. According to various blogs, there are about 170 of them, though the estimates vary.

The history of the cisterns mirrors San Francisco’s history. In the 1850s, after a series of great fires tore through the city, the small but rapidly growing municipal government built twenty-three underground reservoirs that could be drawn on for fire fighting. These cisterns were planted beneath streets in the central part of the city, between Telegraph Hill and Rincon Hill. They weren’t connected to any other pipes, because the fire department intended to use them as a backup water supply, in case the water mains broke in another earthquake.

They languished for decades. Many people thought they should be defunded since they had long gone unused. However, after the 1906 earthquake, fires once again leveled much of the city. Many water mains broke, and the neglected cisterns helped save portions of San Francisco.


Two years after the 1906 earthquake and fires, the city passed a $5.2 million bond to begin building the AWSS, both restoring the first generation of cisterns and constructing many new ones. The largest one is underneath the Civic Center and has a capacity of 243,000 gallons, though most of the twentieth-century cisterns hold about 75,000 gallons of water each. The original ones hold much less water, anywhere from 15,000 to 50,000 gallons.

While working with the cistern data, I kept returning to the formidable task of building a large-scale sewer map. With approximately 30,000 manholes and 30,000 pipes that connect them, I kept asking myself: how do I even begin mapping this? Even the Department of Public Works hadn’t mapped this out in 3D space. I don’t know if any city ever has.


Conventional software modeling packages can’t handle datasets this large, and they don’t enable the kind of artistic expression that I wanted to enable. So, I built my own 3D modeling software using a popular open source toolkit called OpenFrameworks, which supports the ancient C++ programming language. With it, I was able to map out the nodes and pipes in 3D space. While working on my laptop, on a plane ride from Seattle, my code finally rendered a manhole map of San Francisco, and it looked just like the city’s terrain. I let out a yelp of joy at 30,000 feet. The algorithms I created were quick, efficient, and could generate complex 3D models that could directly interface with the 3D printers at Autodesk.

For the sewer portion of Water Works, I chose to 3D print just a portion of San Francisco including the waterfront by San Francisco Bay, the historic Ferry Building, and a section of Market Street. I made the pipes a light gray and the manhole chambers represented by a darker gray. The sewer dataset included the diameters of the pipes and the volume of the manhole chambers, so I scaled the nodes and pipes accordingly, and I found that increasing the Z-axis (elevation) by a factor of three would perfectly accentuate the hills of San Francisco. The results surprised me: a huge sewer line runs down Kearny Street. The Pier 9 Autodesk office, where I was working sits right next to one of the largest underground chambers in the city.

The visualizations of the sewer and cistern data have overlapping, chaotic geometries. They are not to scale—the pieces would be impossibly small. The final prints have a 20-inch by 16-inch footprint and each is about 6-inches high. They took forty to fifty hours to print. They sit on a map made with the help of Stamen Design. I worked with their custom map tiles, and their developers provided me with a high-resolution black-and-white map that I used for laser-etching onto a cherry wood. The final 3D prints rested on pins, attached to the wood. They feel architectural and synthetic, yet organic as they follow the terrain of San Francisco.

To me, the best part about integrating code and sculpture was the uncertainty of form. When I altered my software algorithm, suddenly a 3D model would have an entirely different look. If the cisterns were too large, then the form felt clunky; and if they were too small, well, the 3D print would break in my hands. It wasn’t until I mapped the data in 3D space that I truly understood what it would look like. The combination of code and sculpture is powerful, and yet it takes the control away from my own hands. Like walking through an urban environment, the Water Works project fully engaged my imagination, as I transformed virtual data into physical objects that enable a general audience to appreciate what’s under their feet.


Posted by Boom California