Don't soak rapidrooters. They come per moistened with a bacterial culture that is good for the plants; changing the water content and source changes how effective they will be, and can waterlog them.
If they start to appear dry, sprinkle jsut a FEW DROPS of tap water on them until they look like they did in the bag- keep a few in a sealed ziploc (we all have those lol) to compare moisture levels for your reference.