No especially salt softened. The others = reverse, pot -too expensive,

There must be valves that shut off the softened water to your outside
faucets. They should be very near the softener tank , or the faucets
themselves

If a knowledgable neighbor cant help, or the tank mfg, it would be worth
the plumbing cost. Otherwise neighbors would sue and all levels of govt
would be after you when everything dies.

[It is a Federal offence to apply anything outside but 'approved'
products; or to use them in an unapproved manner; ie- not following
directions to the T]