Most water treatment installs end with a short conversation at the equipment, after the tanks are set, the lines are connected, and the water has run for a while. That conversation is the handoff. It is the point where the installer is supposed to show you how the system works, and it is also the last easy chance to fix anything before the crew drives away. Treat it as a checklist, not a formality. You will be the one living with the system on a Tuesday morning when something looks off, and you will need what you learned here.
Ask them to show you the controls, not just describe them
Have the installer walk you to the unit and point at each control while you watch. If there is a control head or display, ask what each screen means and what the normal reading looks like. If there is a bypass valve, ask them to turn it to bypass and back again while you watch the flow, then ask you to do it once yourself. Confirm which way the handle moves for treated water and which way it moves for untreated, and mark it with tape or a label if the installer does not.
Write down the settings before anyone leaves
Ask for the settings the system was programmed with, and write them on paper or in your phone. For a softener, that usually means the hardness value used, the regeneration schedule or trigger, and the time of day it runs. For a filter or other unit, ask for the flow rate or capacity figure the installer set for and any pressure settings. Ask whether any of these were changed from the factory default and why. If the installer cannot tell you what the settings are, that is worth noting before you sign anything.
Find the shut-offs and the drain
Know where the main water shut-off is for the whole house and where the treatment unit's inlet and outlet valves are. Ask the installer to point out the drain line and confirm it is routed where the local plumbing rules and the manufacturer's instructions say, with an air gap and no submerged end. Ask what a normal drain sound or discharge looks like so you can tell it apart from a leak later.
Get the consumables and the schedule in writing
Ask what you need to add or replace and how often, in the installer's own words, and ask them to write the answer down. For a softener, ask which salt type to use and how to tell when the level is low. For a filter, ask how the cartridge or media change is signaled and what to do when it is due. If there is a replacement part you may need to order, ask where it comes from and whether the installer will supply it or you should buy it directly. Do not accept a vague answer like check it sometimes.
Check the taps and the connections
Before the crew leaves, run a few taps, including one hot and one cold, and make sure water is flowing at each one. Look at every fitting you can reach for drips, weeping, or a film of moisture. Ask the installer to recheck the connections once the system has run under normal pressure. Leaks at a new joint often show up within the first day, so plan to look again yourself that evening and the next morning.
Collect the paperwork and the identifiers
Ask for the model number and serial number of each unit and write them down. Ask for the warranty terms, when the warranty starts, whether you need to register the product, and who handles a warranty claim, the manufacturer or the installer. Ask for the owner's manual and the installation record. Put these together in one folder, because you will need them when you call for service, and the person who answers the phone will ask for the model and serial first.
Ask who to call and what to do first
Get a phone number for the installer's service line and the best time to reach a person. Ask what you should check yourself before you call, such as the bypass position, the salt level, or the display message, so the call is faster. Ask what counts as an emergency that means you should shut off the water to the unit right away. A short, specific answer here saves real trouble later.
Before you sign off
Do not sign the completion paperwork until you have seen the system run, tested the taps, and received the settings, the schedule, and the warranty terms. If anything on the list was skipped, say so on the form and ask for it to be completed before final payment. You can read how we review providers on our methodology page at https://missouriwaterexperts.com/methodology.html if you want to see what we look at when we rate installers.