My Vega, #1868, has two foot-pumps for the galley sink: fresh water and salt
water. The fresh water galley pump cracked open a couple years ago. I
replaced it with one from West Marine. Although identical, the hold-down
bolt pattern is a bit different. If you have both, salt - and fresh water
pumps under the sink, you have to be a contortionist to accomplish the
replacement, but it can be done.
As for yuckies growing in the hoses, I believe it pays to flush the fresh
water tank with about 1/2 gallon of ordinary Clorox bleach and several
gallons of fresh water in the spring. If you do this, be sure to use plenty
of fresh water to clear the Clorox out of the lines and pump before using. I
used to work at Electric Boat Shipyard building submarines. This is the
method used for flushing potable water tanks.
Even still, I carry a separate container of fresh water for drinking, and use
the on-board tank for wash-up as somebody else mentioned.
Good Luck...............Ed