Isaiah 1:22

Thy silver is become dross. Primarily, "thy great men have deteriorated." From pure silver, they have become mere dross, the vile refuse of the smelted ore, only fit to be cast away as worthless. But per-Imps there is some further reference to all that was once precious in Jerusalem; there had been a general deterioration—all the silver was now a debased metal of no value.

Thy wine mixed with water. A parallelism; but (as so often happens) a weakened iteration of the preceding sentiment.