[xoxoxoBruce]

The rust could be in-house, but the sand is coming from outside, somewhere along the line. Since the water is under pressure, it's hard to believe a hole/crack in a water line would allow sand in, so I'm betting the source.

Whole house filters are cheap, readily available at home centers, and easy to replace the element once a year. My well kicks up an ultrafine silt, when disturbed, so fine I can't feel it between my fingers. I've changed the filter just because I thought it was time, and was shocked to find it loaded, crusted, with that silt, but no noticeable drop in water pressure or flow.