Check a 12-inch or larger diameter garden pail for leaks. Seal any cracks with silicone sealant and let it dry. Place the pail in the garden in the desired location for your fountain. Insert a 3-foot long strip of rebar 15 inches into the ground beside the pail.
Cut a 4-foot long section of copper pipe. The pipe is one of the channels for the water, directing it from the pail to the old pump head. Drill a 5/8-inch hole through one side of the pipe, 2 feet from one end.
Solder the copper fitting to the opposite end of the copper pipe from the drilled hole. Fit the open end of the copper pipe over the rebar; position the drilled hole beside the pail. Solder the old water pump to the copper fitting on top of the pipe; position the pump head directly over the garden pail.
Attach a 4 1/2-foot length of flexible plastic tubing to the spout on the submersible fountain pump. Seal the tubing to the pump with duct tape if the fit is loose. Feed the other end of the tubing through the drilled hole and up inside the copper pipe to the base of the old water pump. When you plug in the fountain pump, the tubing will carry water up through the pipe. The water will flow through the old water pump and back into the garden pail.