Jesus entered baptismal waters as a Priestly purification ritual that was well established in Torah as Jesus desired to fulfill all righteousness concerning His ministry and the perception of same that would be judged harshly by the Council, the Pharisees.

Exodus 30:17-21 A large vessel of brass, holding water, was to be set near the door of the tabernacle. Aaron and his sons must wash their hands and feet at this laver, every time they went in to minister. This was to teach them purity in all their services, and to dread the pollution of sin. They must not only wash and be made clean, when first made priests, but must wash and be kept clean, whenever they went to minister. It teaches us daily to attend upon God, daily to renew our repentance for sin, and our looking to the blood of Christ for remission; for in many things we daily offend.

…5And Moses said to them, “This is what the LORD has commanded to be done.” 6Then Moses presented Aaron and his sons and washed them with water. 7He put the tunic on Aaron, tied the sash around him, clothed him with the robe, and put the ephod on him. He tied the woven band of the ephod around him and fastened it to him.… Leviticus 8