Most homeowners think about the tank, the cartridge, or the price first. The permit and inspection often get left for later, and that is where a clean install can turn into a rework job. Whether a permit is needed depends on your city, county, and whether your water comes from a private well, so ask before anyone starts. Your answers decide who is responsible if something has to be opened up and redone.
Find out whether a permit is required
Ask the installer directly: will this job need a permit where my home is, and if so, which office issues it? Work that touches plumbing, electrical connections for a pump or UV lamp, or a well system can fall under different rules. If the answer is vague, call the local building or permitting office yourself and ask what kind of work they cover for water treatment. Write down the office name, the phone number, and the name of the person who answered.
Decide who applies and who pays
Some installers pull permits as part of their quote. Others expect the homeowner to apply. Neither is wrong, but the difference should be on paper. Check whether the permit fee is listed as a separate line or included, and whether the permit is in the installer's name or yours. If you are the applicant, ask for the exact description of work they plan to submit, so the permit matches what will really be installed.
Match the permit to the job
Compare the permit description with your quote and the equipment list. Look for these points:
The type of system, such as softener, filter, UV, or well equipment, should match what you are buying.
Any plumbing changes, such as new bypass valves, relocated lines, or a new drain connection, should be named.
Any electrical work, such as a new outlet for a pump or UV unit, should be named and assigned to someone licensed to do it, if your area requires that.
If the permit says one thing and the crew plans another, fix the mismatch before the first day.
Know when the inspection happens
Ask when the inspector must see the work. For many installs, the key moment is before walls, trenches, or fill cover the piping, and again after the system is connected. Ask who schedules the inspection, how much notice is needed, and whether the crew will be on site when the inspector arrives. A crew that cannot tell you the inspection points has not planned them.
Get the sign-off in writing
A passed inspection should leave a record. Ask for the permit number, the inspection date written on the permit card or report, and a copy of the final approval when it is issued. Keep these with your install folder, along with the quote and warranty. If an inspection fails, ask what was flagged, who will correct it, and whether the correction is included in your price.
Ask your insurer or local office about unpermitted work
If a job is done without a required permit, you may face problems later with resale, insurance claims, or a local code notice. Those rules differ by place, so ask your insurance agent or the local permitting office what they would expect to see. This is a question to confirm, not a point to guess about.
When you compare providers, ask each one how they handle permits and inspections, and get the answer in the quote. For help finding installers who work this way, see the 2026 Directory of Water Treatment Providers in Missouri, and for how providers are evaluated, see our methodology.