Yes but if the water softener is a capital improvement to your home before you converted to a rental, then you would add the cost of the unit to the cost basis in your house and use this higher cost basis as the basis in your rental for deprecation.
A "capital improvement" to your home, meaning the improvement must increase your home's value, adapt it to new uses, or extend its life. Examples of capital improvements are: adding a third bedroom, adding a garage, installing insulation, landscaping and more.
To enter rental information in TurboTax, log into your tax return (for TurboTax Online sign-in, click Here and click on "Take me to my return") type "rental income and expenses" in the search bar then select "jump to rental income and expenses". TurboTax will guide you in entering this information.