How long should I keep pet turtles out of water??

Aquatic (pond) turtles need to have both sunbathing and water available to them at all time. Because turtles are cold-blooded, they regulate their body temperature by changing their activity levels and moving to different temperature surroundings. Accordingly, they need to be able to go from warm and dry to cooler and wet all the time (and preferably cool and dry, and warm and wet too!). Only the turtle's body knows when it needs to make the move, so it can't rely on you to do that. Get your little guys some floating rocks or platforms, or a ramp to get out, if they don't already have it.

Interrupting a turtle's homeostasis of body temperature can negatively impact it's ability to digest its food, cause stress, and ultimately open it up to poor health.

With that said...when you need to take your turtles out of the pond area--let's say there is abnormal cold or storm, for instance--you can keep them in a predominately dry area for many days as long as they have a soaking bowl available. If they get stressed and don't get into the bowl in these situations, spray them down with a squirt bottle a few times a day.

not good, they like to sunbathe and be on land for short stretches but they are WATER animals you do not want them to dry out, they should have access to water always so that they can get out when they want and go back in when they want as well

no, they do need water daily. :)