Water Baptism

John was baptizing people in AEnon near to Salim, because there was much water there.

John baptized there, because there was adequate water. He didn't baptize there because it was a river. Or for any other special reason. It was simply a matter of whether there was enough water.

When Philip and the eunuch went on their way, they came unto a certain water: and the eunuch said, "See, here is water; what doth hinder me to be baptized?"

It doesn't say it was a river. It just says, "A certain water". The issue was not the type of water-system - all that mattered was whether there was enough water for two people to stand in the water and for one of them to be immersed.

Philip said, "If thou believest with all thine heart, thou mayest." And he answered and said, "I believe that Jesus Christ is the Son of God."

And he commanded the chariot to stand still: and they went down both into the water, both Philip and the eunuch; and he baptized him. And when they were come up out of the water, the Spirit of the Lord caught away Philip, that the eunuch saw him no more: and he went on his way rejoicing.

They both went into the body of water, and came up out of it. That's all that matters. You only need enough water. It doesn't necessarily have to be a river. Or a baptistry. Just enough water - that's all you need.