Installers work through a set order, and the owner's job is to know what should happen at each stage. You do not need to do the plumbing to follow the process. You need to see that each step is finished before the next one starts.

Step one: the site survey

The installer looks at where the equipment will sit, the pipe size and material coming in, the access to the space, and the power source if one is needed. Ask for the survey findings in writing. Confirm that the location leaves room for service access, including room to remove a tank or cartridge housing and to reach the bypass valve.

Step two: confirm the sizing and scope

Before any parts are ordered, the installer should state the sizing basis, meaning the flow and water test numbers used to choose the equipment. Compare the scope against what you agreed to, line by line. If the scope names a bypass valve, check that it is listed. If it does not, ask why.

Step three: permits and inspection

Some installations need a permit and an inspection before or after the work. Ask the installer who pulls the permit and when the inspection happens. Do not let work start on a schedule that skips a required inspection.

Step four: shutoffs and the bypass plan

Before cutting any pipe, the installer should show how the water will be shut off and how the house will be supplied during the work. Ask where the main shutoff is and whether the crew has checked it works. Agree on how long the water will be off and when you will be told.

Step five: tie-in and fit

This is the cutting, fitting, and connecting stage. Look for clean, straight cuts, proper fittings, and no visible leaks as the lines are reconnected. Watch the drain connection if the system needs one, and confirm the location of the drain point with the installer before it is fixed in place.

Step six: media, startup, and flush

The tank or housings are loaded, the system is started, and water is run to flush the new media or cartridges. Expect the water to look cloudy or carry fines for a short period. Run the taps you use most until the water runs clear. Confirm the flush was completed, not just started.

Step seven: test and startup record

Test the water at a tap after the system settles. Ask for the startup record, which should list the settings the installer used, the flush steps taken, and the readings taken at startup. Keep it with your home binder.

Step eight: walkthrough and handover

Walk the system with the installer. Ask them to show you the bypass, the shutoff for the system, the service points, and where the manuals and spare parts are. Confirm who to call for service and what the warranty covers before you sign off.