Water softeners are plumbed into your main water line — usually near the meter if you’re on city water or your compression tank if you have a well. A basement is ideal because pipes are handy, and it’s out of the way. A garage, utility room or closet are other options, but you may have to run plumbing and add electricity and a drain. In warm climates, softeners can be installed outside with adequate protection from cold and sun — it can’t be allowed to freeze. And a crawlspace will do as long it’s deep enough to install the softener upright and allow room for maintenance.