I almost forgot: In general, swimming pools symbolize the spiritual or financial situation of a family or a church. The color and the condition of the water will reveal more information about the financial situation or the spiritual condition of the congregation or the family.
In another sense, a swimming pool speaks of the excitement and enjoyment in terms of the ministry and functioning of the gifts of the Holy Spirit. It speaks of the preparation and training and excitement and joy to minister in the flow and inspiration of the Holy Spirit.
It depends on what other symbols are involved in the dream or vision to determine what it really means.