John 3:23
John also was baptizing at Aenon near Salim, because water was plentiful there, and people were coming and being baptized
because water was plentiful there
Our word "baptize" transliterates the Greek (βαπτίζω), which itself is just the verb form of the word for dunking (βάπτω).
βάπτω
- dip, ("so as to temper the red-hot steel")
- dye, ("dye the beatiful cloths")
We note that this word, βάπτω, which can be transliterated "bapto", sounded to the Greeks like the sound of water closing over the top of something that has been dunked or dipped.
βαπτίζω
- dip, plunge
- in passive voice: to be drowned
- of ships: sink or disable them
- "flooded the city": metaphorically, of the crowds who flocked into Jerusalem at the time of the siege
- to be drenched, soaked
- "over head and ears in debt"
- "seeing that he was getting into deep water"
- draw wine by dipping the cup in the bowl
And we note here the ancient use of the term "baptize" (βαπτίζω) was unambiguously about an overwhelming amount of liquid, whether that was enough to fill a cup by dunking or enough to sink a ship. This is why the Ethiopian eunuch in Acts 9 (below) would have been looking for a body of water in which to be baptized. He obviously would have had plenty of drinking water in the traveling company; he was just getting started on a desert journey back to Ethiopia. But drinking water is stored in drinking vessels, and not accessible for completely overwhelming an adult in water.
Acts 8:26–28, 36, 38–39
Now an angel of the Lord said to Philip, "Rise and go toward the south to the road that goes down from Jerusalem to Gaza." This is a desert place. And he rose and went. And there was an Ethiopian, a eunuch, a court official of Candace, queen of the Ethiopians, who was in charge of all her treasure. He had come to Jerusalem to worship and was returning, seated in his chariot....
And as they were going along the road they came to some water, and the eunuch said, "See, here is water! What prevents me from being baptized?"
They both went down into the water, Philip and the eunuch, and he baptized him. And...they came up out of the water....
1 Corinthians 10:1–2
Our fathers were all under the cloud, and all passed through the sea, and all were baptized into Moses in the cloud and in the sea....
Romans 6:3–4
Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life.
1 Peter 3:20–21
God's patience waited in the days of Noah, while the ark was being prepared, in which a few, that is, eight persons, were brought safely through water. Baptism, which corresponds to this, now saves you, not as a removal of dirt from the body but as an appeal to God for a good conscience, through the resurrection of Jesus Christ....