First, think like a plumber (minus the pipe wrench wedgie). Your softener needs to treat all the water coming in. That means it sits right after the main water shut-off valve. But before the water heater. Got it?
Where is that valve? Usually in a basement, a crawl space, or a garage. It’s the spot where water enters your home. That is the prime real estate.
Don’t have a basement? No worries. Many folks tuck it into a laundry room. Right next to the washing machine. It’s cozy there. It’s practical. It’s a party for your pipes.