Note 4 at Acts 2:41: Many people have argued that 3,000 people could not have been water baptized in one day, especially since there was no naturally flowing streams or pools within the city of Jerusalem. However, there were man-made pools within the city that would have proven adequate.

The pool of Siloam, which was immediately south of the temple, would have been adequate. It is 50 feet long and averages 16 feet wide. This is the pool that Jesus instructed the blind man to go to and wash in (Jn. 9:1-7).

The upper and the lower Gihon pools were also nearby and suitable for water baptisms. The upper Gihon pool was 316 feet long and 218 feet wide. Archaeologists have also uncovered many ritual immersion bath pools adjoining the temple complex. There were more than enough pools of water to perform 3,000 baptisms.

As to the time that it would take to baptize 3,000 people, that also could have been easily done. If only one person was baptized every minute or 60 per hour, twelve men could have baptized 3,000 people in four hours and fifteen minutes.

Also, as mentioned in note 6 at Matthew 28:19, p. 564, any believer can administer water baptism, so there could have been many more than twelve who were baptizing. It is also possible that the people baptized themselves without another's assistance as the converts to Judaism did in the temple's ritual baths and as some people think John the Baptist administered water baptism (Understanding the Difficult Words of Jesus by Dr. Roy Blizzard, p. 136).