if we put the financial aspect aside to me, when you say something is above the water, it can either mean partially or totally, however when you say something is over the water, then there is no connection between the object itself and the water. swim with your head above the water, but part of your body still remains in the water. birds fly above the water, not touching. but if you swim over the water, you are a superwoman.

"Under water" expresses the idea of financial difficulty, namely an asset encumbered for an amount greater than its current value. The opposite is "above water". "Over water" might describe a route over the ocean, for example, "our flight was mostly over water".

above water: staying in good economic position do not know about over water...