Bill wrote:

I looked at several in the ship's store. They all had grease in the plastic
rotating seacock-like valve. I don't want grease in my drinking water.

I guess I could try and clean them up before I install them. Is there
another solution?

Avoding hydrocarbon grease in drinking water is probably a good thing.
But what grease was it?

If the diverter valves were meant for potable water, the grease was
likely silicon grease. Silicon grease is reasonably inert (the silicion
is inert, the solvent is volatile to the point that a tube of silicon
grease only has a shelf life of 18 - 24 months; it's still useable
after that date but its consistency has changed).

Teflon is used as in some higher priced diverter valves meant for
drinking water. Look for valves with a teflon coating on the
rotor/stator.

Cheers