The lotus-leaf that lies afloat on a piece of water is separate from the piece of water on which it floats. Because it exists with water it does not form a portion of the water.
पुष्करं त्वन्यदेवात्र तथान्यदुदकं स्मृतम्। न चोदकस्य स्पर्शेन लिप्यते तत्र पुष्करम्॥