Last updated: September 29, 2022
Upper Geyser Basin in Yellowstone National Park
Old Faithful erupts more frequently than any of the other big geysers, although it is not the largest or most regular geyser in Yellowstone National Park. It is believed this regularity is in part due to no known connection with other hydrothermal features in the area.
Its average interval between eruptions is about 90 minutes, varying from 50 to 127 minutes. An eruption lasts 1.5 to 5 minutes and expels 3,700–8,400 gallons (14,000–32,000 l) of boiling water, and reaches a height of 106–184 feet (30–55 m). Old Faithful Geyser has an average temperate of 169.7°F (76.5°C), an average pH of 9, and an average conductivity of 1972 uS/cm.
Limited parking, especially 10 am-6 pm.
Members of the Washburn expedition of 1870 named this geyser for its consistent performance. Although its average interval has lengthened, Old Faithful is as spectacular as it was a century ago.
The geyser is the centerpiece of the Old Faithful Historic District. The surrounding buildings are all set back from the geyser about the same distance: 1/8 mile (0.2 km). Only two buildings have been allowed to infringe upon this distance, established by Federal law: the Old Faithful Inn's east wing and the Old Faithful Lodge.
Geysers have constrictions in their plumbing systems that prevent water from moving freely to the surface where heat would escape. Water beneath the constrictions creates a buildup of steam. Eventually the steam pushes water past the constrictions and the geyser erupts.
Upper Geyser Basin
The majority of world’s active geysers are in the Upper Geyser Basin, including Old Faithful. Only four other places in the world have large concentrations of hydrothermal features: Russia (Kamchatka), Chile, New Zealand, and Iceland.
The heat for the hydrothermal features comes from Yellowstone’s volcano. Molten rock or magma may be as close as 3-8 miles (5-13 km) underground. Rain and snow supply water that seeps down several thousand feet (more than a kilometer) below the surface where it is heated.
Underground cracks form a natural plumbing system. Hot water rises through the plumbing to produce hot springs and geysers.
Use Caution in Hydrothermal Areas
- Stay on boardwalks and designated trails.
- Hydrothermal water can severely burn you.
- Never run, push, or shove.
- Supervise children at all times.
- Do not scratch hydrothermal mats.
You are responsible for your safety.
Think safety, act safely. Yellowstone is a dangerous place.
Wheelchair-accessible walkways lead from all parking areas to Old Faithful Geyser, and from the Old Faithful Visitor Education Center to other hydrothermal features.