According to the latest published in Journal science, water came into the inner part of solar system long before than the scientists thought it would have come. It came into knowledge that the water entered our solar system after 8 to 10 million years of its birth.
The age of solar system has not been confirmed, but it was thought to be near 4.6 billion years. Formerly, it was considered that asteroids were responsible for bringing water to Earth. But now it has been confirmed that how and when water came to Earth.