The tank you will use for the ceremony must be filled with water and obviously this will not be done, but with the aid of an automatic fill system, consisting of a valve and a float switch. These systems can be found at a rather small price and can be added to existing plumbing. You could automate the system even more if you want, just by adding a drain valve that can be operated from the same control unit.
But the water in the tank can be too cold, thus making baptism less comfortable and safe. So, you will have to come up with some heating solutions, as a standard water heater is not able to fill a baptism tank with warm water!
You could try filling the tank with cold water and use either a submersible heating element or a circulating system and heater. A submersible heater does not require additional plumbing or a circulating pump. This is not an expensive thing to do, but it does have a drawback: it can take a lot of time to bring the water up to temperature. The only option you get in this case is to fill the tank and start the heater the day before the baptism.
The best way to get the water warm is to use an on-demand style water heater that continuously delivers hot or warm water. Yes, you guessed it right, this kind of heater can be used to deliver hot water to the kitchen.
Water can also be quickly heated should you use a circulation system, even if it requires additional plumbing, a separate water heater, a pump and controls. The temperature controls can be integrated with a fill and drain system to completely automate the filling and heating processes.
In terms of safety, the first thing to keep in mind is installing some handrails that will help the candidate into and out of the baptism tank. This safety problem is especially important when the steps or bottom surfaces of the tank are smooth and can cause people to slip. So get some nonskid decals, if needed.
Once this is all set, if there is enough time, think about getting some painted background scenes for the wall behind the baptism tank.
