The immersion baptistery symbolizes the truly repentant believer’s identification with Christ his Savior in death, burial, and resurrection to walk in new life. This service is a wonderful time for testimony and evangelistic appeal. The physical process must be dignified to avoid distraction from this biblically prescribed public ordinance of the local church.
During my many years of church facility development consultation, I have seen many designs for the immersion tank. I’ve seen a horse trough used. I watched the deacon of the pastorless church baptize the scared lady a second time because another deacon yelled from the back of the room that her arms were not under the water. I recommended the closing of the baptistery with access only through the window from the choir area.
I recently observed access to a baptistery 20 feet straight up a steel spiraling stairway. I learned of the candidate who was nearly electrocuted by the makeshift heater dropped into the water (while the pastor was insulated by his rubber waders). I heard of the man who was toweling to dress after his baptism, slipped on the wet floor at the front of the church with the portable baptistery behind screens, knocking down the screens, and exposing himself to the congregation.
Rural people may tolerate the makeshift baptistery. But most people expect a convenient, modest, comfortable setting. I strongly recommend a manufactured fiberglass baptistery with an automatic, thermostatically controlled heater to bring the water to a comfortable temperature. Provide waders and a baptismal robe for the pastor. Use modest robes for the candidates. An operable curtain or strategic wall placement can help provide the necessary modesty.
The double entry baptistery is preferable to allow separate access to separate dressing areas for each gender. There should be a toilet accessible to the candidates. I believe it is the ideal arrangement to design private dressing rooms large enough and appropriately designed to also serve as counseling rooms following public service invitations. Avoid having the dressing rooms and baptistery area used as storage areas cluttered with the junk I often see (ladders, old plastic flowers, boards, leftover literature, old sound systems, worn-out hymnals, etcetera).
If you are limited to a temporary arrangement, be sure it is safe and modest. (Or go to a neighboring church with an adequate facility.) Some communities have tried to enforce barrier-free access into the baptistery; I am finding these requirements to be less stringent in current enforcement. However, give due consideration in your baptistery design to access for special situations.