Purgatory Brook

General data
- Name: Purgatory Brook
- Water system: Merrimack River
- Water type: Stream
- Progression: Souhegan River -> Merrimack River -> Gulf of Maine -> Atlantic Ocean -> Planet Earth
- Climates: Temperate
- Continents: North America
- Countries: United States of America
Description
Purgatory Brook is a 5.8-mile-long (9.3 km) tributary of the Souhegan River in southern New Hampshire. It rises in a marshy area on the border of Lyndeborough and Mont Vernon, and flows south over three small waterfalls, intersecting the Souhegan in Milford. For much of its length, it constitutes the border between Lyndeborough and Mont Vernon.