keep (one's) head above water
1. Literally, to hold one's head out of the water as to avoid drowning. This lifejacket will help Sally to keep her head above water in the pool.
2. To (barely) avoid being consumed by a stressful or unpleasant situation (often related to work or finance). If credit cards are the only thing keeping your head above water, then your situation is more dire than I thought.
head above water, keep one's
Stay out of trouble, especially financial difficulties; also, keep up with work or other demands. For example, With new bills coming in every day they're barely keeping their heads above water, or The work's piling up, but I manage to keep my head above water. This expression alludes to keeping oneself from drowning. [Early 1700s] Also see in deep.