Most softener quotes show a monthly or up-front price, and that price can hide who owns the tank. A purchase, a lease, and a rental can all arrive with the same installer, the same unit, and the same friendly sales call. The paper decides what you actually get, so read the ownership sentence before anything else.
Find the sentence that names the owner
Look for wording such as 'title remains with,' 'property of,' or 'the equipment remains the property of.' If that wording appears, the company keeps ownership no matter how many payments you make. If the paper says you own the unit outright, check whether that appears in the body of the contract or only in the sales summary. Ask which document proves ownership after the last payment, and whether it arrives on paper.
Read the end of the term first
Find out what happens when the agreement ends. Some contracts convert to ownership for a stated buyout amount. Some renew automatically unless you send notice inside a set window. Some end with the company picking the unit up. Write down the notice window, the exact method for giving notice (mail, email, or a form), and who has to sign it.
Check the exit and removal terms
Ask who pays for removal, how long the company has to come get the unit, and what they leave behind. A tank that goes out while the plumbing is left unfinished is a separate job, so the contract should say who caps the lines and who repairs any damage to the floor or wall.
Decide what happens if you sell the house
A lease or a financed unit may not follow the house. Ask whether a buyer can take over the agreement, whether there is a transfer fee, how much notice you must give before closing, and whether a payoff letter is needed. Get the answers in writing, because a closing date is a poor time to learn that the contract blocks the sale.
Confirm who keeps it running
Under a lease or rental, the company often carries the repair obligation for the full term. Under a purchase, the repair obligation may fall to you once the manufacturer coverage ends. Check whether the agreement says the company will service the unit, how quickly, and whether salt or filter costs are included or billed on top.
Compare two papers on the same four lines
Put two contracts side by side and fill in four lines: who owns the unit, how long the term runs, how you exit, and what transfers when the house does. If a company cannot fill in a line from its own paper, treat that line as unanswered. Ask for the complete contract rather than a summary, and have someone you trust read it before you sign.