Some meteorites, particularly the CI class, currently contain water. As these include both finds (with their Earth entry and impact unobserved) and falls (meteorites from a known, recent meteor event), that water cannot be entirely terrestrial contamination.

What do meteorites contain?

More than 95% of meteorites observed to fall to Earth are stony. They can be divided into chondrites and achondrites. Both types are composed mostly of silicate minerals, but the great majority also contain metallic iron in small-scattered grains.

What asteroid has water on it?

The largest asteroid in the solar system seems to have a salty ocean of water sitting deep beneath its surface. Ceres, the largest asteroid in the solar system, seems to have liquid water seeping onto its surface, according to a new paper in Nature Astronomy.