When a house changes hands, the water treatment equipment changes hands with it. The next owner inherits whatever you leave behind: a system they understand, or a box in the utility room that nobody can explain. A clear record takes an afternoon to assemble and saves the buyer a string of phone calls to learn what is installed, how it is set, and who services it.

Start with what is actually installed

Walk the house and list every treatment piece, including the small ones you may not think of as equipment. Note the location, the type (softener, sediment prefilter, carbon filter, reverse osmosis unit, UV unit, iron filter, or other), and whether it serves the whole house or a single tap. Find each shutoff valve and bypass valve, and label which one controls which unit. A buyer who cannot find the shutoff during their first leak is the buyer who calls you at night.

Sort owned from leased

Before you list the house, find out whether each unit is owned outright, financed, or rented. A rental or lease agreement may require the equipment to be returned, transferred, or bought out at closing, and a loan may stay attached to the property or to you. Pull the paperwork for each unit and read the transfer and cancellation sections. If something is unclear, ask your real estate agent or the attorney handling the sale what your documents require, and ask the company that owns the unit the same question in writing.

Assemble the owner packet

Put the following in one folder, paper or digital, and label it clearly.

The manual for each unit, plus any installation or startup sheet from the installer.

The model and serial number for each unit, written on the first page so nobody has to open a cabinet to find them.

The warranty terms, with a note on whether they transfer to a new owner and what the claim steps are.

The service history: every filter change, media check, salt refill, lamp or cartridge swap, and repair, with what was done and by whom.

The name and phone number of the company that installed or services each unit, plus any maintenance agreement terms.

Your most recent water test results, if you have them, with the name of the lab and a note of what was tested.

Write down the settings and the routine

Record the settings each unit is running: the softener hardness setting and regeneration schedule, the filter bypass position, any pressure settings, and the reminders you use for replacements. Add a short note on what gets checked and how often. The buyer does not need to become a technician, but they do need to know that a filter gets changed, that a softener needs salt, and that an RO storage tank should be checked. Mark which tasks belong to the owner and which need a service call.

Walk the buyer through the equipment

A folder is most useful when someone shows the buyer the equipment in person. Spend about fifteen minutes at the units. Show the shutoffs, the bypass, the power switch, the salt level or filter status indicator, and where the records are kept. Confirm they have the service contact information. Put in writing that the walk-through happened and what it covered, so nobody later disagrees about what was handed over.

Leave a one-page cover note

One page is enough. List what is installed, what is owned versus leased, who to call, what to check first when the water looks or tastes wrong, and where the packet is kept. Keep the tone plain. A buyer reading it should be able to make the next decision without guessing.