Many water treatment installs involve cutting into supply lines, adding a bypass, and connecting to a drain. Depending on where you live and what is changed, a permit and an inspection may be required. The contract should say who handles that rather than leaving it to assumption.
Confirm whether a permit is needed for your job
Rules vary by city and county, and they can depend on the scope of the work. Ask the company whether they believe a permit is required for this specific installation, and check with the local building or plumbing department yourself if you want to confirm. Do not assume a permit is unnecessary because the equipment is sold as a home appliance.
What the contract should spell out
Look for a clause that names who applies for the permit, who pays the fee, and who schedules the inspection. Check whether you need to be home for the inspection, and whether the installer must correct anything an inspector flags, and at whose cost. The contract should also say whether you will receive a copy of the permit and the inspection result once the work passes.
Questions to ask before you sign
Ask whether the work will be permitted and inspected before the system is put into use. Ask what happens if the inspection fails, how long a correction could take, and whether the company will return for a re-inspection without an added charge. If the answers are vague, ask for them in writing and keep the reply with the quote.
Keep the record
Save the permit, the inspection result, and the final sign-off with your home records. Permitted work can matter later, such as when you sell the house or when you talk with an insurer, depending on local rules. If you have a specific question about how that applies to your home, ask a real estate or insurance professional rather than relying only on the installer's summary.