Building an indoor water fountain is possible by putting a pump and fountain into a bowl of any size and camouflaging the pump inside the bowl with rocks. This can be done with a pre-made fountain pump that is made specifically for indoor use.
It is a good idea to choose a bowl with a flat bottom on both the outside and inside. This will ensure that it remains in a stable position and that the pump will not be able to move around. For larger indoor fountains, cover the pump with protection, such as an upside down clay pot. The protection will ensure that the rocks do not crush the pump with their weight.
While indoor fountains are a great idea, there are some precautions that should be taken. The fountain should always be set up and tested outside where it will not matter if it doesn't work, overflows or sprays out. It is also important that the fountain be plugged into a grounded outlet to ensure that there is a little or no chance of electrocution should the fountain leak out into the cord of the pump. If the fountain accumulates algae, a teaspoon of bleach should help eliminate it.