Yes, tap water usually contains both dissolved oxygen and carbon dioxide. These gases can be introduced into the water during several steps of the treatment process. Atmospheric air naturally contains both oxygen and carbon dioxide, which can dissolve into the water during aeration or when water is exposed to the atmosphere. Additionally, some water treatment plants intentionally add oxygen to the water for various purposes, such as removing dissolved iron or manganese. When water is disinfected using chlorine, it reacts with organic matter and produces carbon dioxide as a byproduct. The dissolved oxygen and carbon dioxide levels in tap water can vary depending on the water source, treatment processes, and local regulations.