far and wide
溥 centers on vastness and wide distribution: something that extends far and wide, covering a large area or reaching everywhere.
溥 combines 氵 (water) with 尃, which likely contributes the sound and the idea of spreading or extending. The character suggests water spreading far and wide.
Water 氵 spreads out over a wide area, covering everything like a flood. The right side 尃 reinforces the idea of extending everywhere.
For フ, imagine a huge flood spreading far and wide: the sound of rushing water is like 'foo' (フ), covering the land.