I see these rooftop water towers every day, but hardly notice them any more… until I spot one lit strikingly by the late afternoon sun. In the 1800s the original water tower builders were barrel makers who expanded their craft to meet the need for water pressure as buildings in the city grew taller in height. Even today, no sealer is used to hold in the water. Tank walls are held together with cables but water leaks through the gaps when first filled. As the wood swells, the gaps close and become impermeable. These rooftop tanks are among the oldest and most chemical-free structures still in use!