With just a glance at downtown Chicago’s modern skyline, you may not guess that the city celebrated its 178th birthday this week. The toll of time is much easier to see below the city streets. There, a complex labyrinth of pipes delivers billions of gallons of water from plants like the Jardine Water Purification Plant—the largest of its kind in the world—to millions of homes and businesses. Roughly 900 miles of the region’s water system is more than a century old, and leaks are an all too common problem. In fact, around 22 billion gallons of treated water is lost each year through leaky pipes and broken lines.