Interesting that the homonym ‘leach’ for the action of liquid percolating through another material comes from the Old English ‘leccan’ - ‘to water’
is that likely to be related?
I don’t think there’s a relationship. The word you’re referring to is spelled leach.
Etymology: Probably repr. Old English lęccan to water (translating Latin rigare ) < West Germanic type *lakkjan < *lakjan , < *lak- : see lake n.3 There appears to be no trace of the verb between Old English and the examples of the technological use in the 18th cent., except the doubtful instance in Shakespeare and one other (see 1, 2 below). The form letch is normal; the variant leach is phonologically obscure.(Show Less)
†1. trans. To water, wet. Obs. rare.