Command Water

This allows you to command water of a certain size, determined the tier of spell. You can only command water you can see, or that is part of a body of water that you can see. Most of the effects listed below assume you have a good amount of water to work with.
A zone's worth of water is somewhat arbitrary, but think of a large swimming pool, enough water to fill a small house, or the water a small ship is floating in.

Cantrip

This allows you to command a bucketful of water. You can move it at walking speed within the zone, or wash something that isn't resisting.

Great

This allows you to command an entire zone full of water. You can move it at walking speed into an adjacent zone, and anyone in that water you want to drag along with it must make either a Soul/Warding or a Strength/Athletics roll to escape the water. They get to choose, but they may only do one. This can instead leave those targets trapped in a whirlpool while those you wish to spare can move freely. This is usually enough water to move a ship. You can also part the water to allow people to walk through.
If you cast this spell to move a cantrip's worth of water, you can move it to anywhere in range at enough speed to do 1 nonlethal damage as well as drench most targets. You can instead forcefully wash someone who does not wish to be washed.

Superior

This allows you to command all water within range, doing all the things at the great level but on a much larger scale. You must do the same effect across all zones, or you can choose to leave some zones dry and others wet.
You can instead concentrate on the great version, maintaining control of a zone's worth of water. Or you can move all the water in one zone to any zone within range, moving anyone who was in it along for the ride and, if you wish, dealing nonlethal damage equal to your Magic Power and leaving them prone and at a disadvantage to their next action.

Ultimate

This gives you complete control over all water in range for as long as you concentrate, otherwise as per the superior version of this spell.