John J. Carroll Water Treatment Plant, Water treatment facility in Marlborough, Massachusetts, United States

The John J. Carroll Water Treatment Plant is a modern facility in Marlborough that receives water from Wachusett Reservoir and purifies it through multiple treatment stages. The plant uses ozone, ultraviolet light, and other processes to deliver drinking water to households throughout the Boston region.

The facility opened in 2005 after years of planning and construction to replace an earlier plant. The new installation brought improvements to water quality and the efficiency of regional supply.

This facility represents how a modern region organizes the delivery of clean water to millions of residents across multiple communities. It demonstrates the infrastructure that supports daily life in the greater Boston area.

The plant is located roughly 40 kilometers (25 miles) west of Boston and is accessible by road. Visitors should note that this is an operational facility, so access and tours may be limited depending on security protocols.

The plant uses specialized ozone generators and a solar array on its grounds to power some of its operations through renewable energy. This demonstrates the use of sustainable technologies in public water infrastructure.