This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
澯 combines 氵 (water) with 粲, which likely contributes sound. The exact historical development is uncertain.
The left side is water 氵, and the right side 粲 contains 米 (rice) and other elements. Picture clear water washing over polished rice, making it bright and clean.
For サン, imagine the sun (サン) shining on clear water: sun -> サン, and the water sparkles clean and bright.