The amount of time you can swim is another factor. Most Masters teams (for swimmers past college) have practices that are 60-90 minutes long. If you're exhausted after swimming for just 30 minutes it may be worth it to build up your endurance a little before joining the team.

Hey Patrick- How far you can swim isn't necessarily the best determining factor on whether you're ready to join a team. Instead, how is your technique? I would suggest taking a few swim lessons or swim classes before joining a team. That way, you can really improve your technique and have a solid base before you start practices.

If you are concerned about distance, most teams swim about 2,500-3,500 yards in a practice. At the beginning of the season, though, the yardage is usually significantly lower than that. Don't let that number deter you, though! With some practice, you'll be swimming far in no time!