Like every sport, swimming follows a strict set of rules to ensure competitive balance and to protect the safety of its athletes. Any swimmer who violates the rules may suffer an immediate disqualification. The exact reasons for disqualification may vary depending on the race's precise swimming stroke or style.
At the start of a race, swimmers must take a stationary position atop the starting blocks. If a swimmer leaves the starting block before the starting signal or is moving as the signal sounds, he or she commits a false start violation and receives an automatic disqualification. If they don't immediately halt the race and recall the swimmers, officials may wait to disqualify the guilty part until the race's completion.
Officials may disqualify a swimmer who fails to report to the starting platform prepared to swim at the start of his scheduled heat. Any swimmer who intentionally delays the start of a race or who willfully ignores or disobeys the orders of officials may also receive a disqualification.
Swimmers may receive a disqualification for violating certain rules while in the act of swimming. Failing to touch the wall when executing a turn, grabbing the lane markers, using the lane markers for momentum or pushing off the bottom of the pool will all result in a disqualification. Swimmers also earn disqualifications for entering another swimmer's lane and for staying underwater longer than 15 meters at the start of a race.
When competing in a backstroke race, a swimmer must remain on his or her back and employ a proper double-armed backstroke or an elementary backstroke. Aside from stroke violations, the majority of backstroke disqualifications occur on turns, with swimmers leaving their backs too soon and gliding to the wall on their stomachs or failing to push off the wall while on their backs.
Most breaststroke disqualifications occur on turns as well. Swimmers must touch the wall with both hands simultaneously. Touching with only one hand or touching with one hand before the other results in a disqualification. Performing more than one dolphin kick before initiating a breaststroke kick when pulling out of a turn, or taking more than one arm pull underwater can also earn a disqualification.
As in the breaststroke, butterfly swimmers must also touch the wall on turns with both hands simultaneously to avoid disqualification. Employing an illegal kick, usually a flutter kick, will also earn a disqualification.
In relay races, swimmers typically draw disqualifications for false starting, which occurs when one swimmer leaves the starting block before his or her teammate touches the wall. A relay team may also get disqualified for entering the pool to celebrate a victory before all other swimmers finish the race.