Compared with the drownproofing sequence, treading water lets the swimmer maintain visibility and retain more body heat since his head is out of the water. However, it requires more physical exertion.
Keep your body upright with the head out of the water. That way you stay in one place until rescue comes. If you need to move a bit, lean in that direction.
Hand and Arm Movements:
Make slow sculling movements underwater to maintain the vertical body position. Don't overexert yourself.
Make slow, continuous bicycle-like or scissor-kick type movements to support your body. Your feet move in a circle.
Raise your arms above your head and use just the legs to keep afloat. This is very exhausting.
Add more clothes as you get stronger. This is a great training exercise. Include it in each swimming session and team up with your friends.