Ordinary concrete will not contain water, which given enough time will wick its way through. All the same I've made a series of fountains for my backyard over the years. This was my earliest attempt.
It's an acrylic box, containing an acrylic pyramid, , the base of which was cast into vinyl concrete patch. I thought the vinyl in addition to the acrylic would keep it watertight. The power cord for the pump was cast through the side of the concrete. The pump was placed under the pyramic and connected to the top of it by means of a clear hose. The larger pyramid had a smaller one on top of it rotated forty-five degrees. Water poured off the inside of this smaller one in two small streams on opposite sides. Lava rocks were placed along the bottom. It was my own metaphor for earth (the concrete), air (the pyramid), fire (the lava rocks) and water.
By the end of summer the concrete had cracked. By the end of fall it could no longer contain water. The following year it completely fell apart and collapsed.