Most people compare the first number on a water treatment quote and stop there. The bigger surprises tend to come later, when the installer adds work, asks for money early, or the homeowner wants out. All three situations are decided by the paperwork you sign at the start, not by what anyone says on the phone.

Find the change order terms

Ask how extra work gets approved. A clear contract says the installer must describe the added work, state a price for it, and get your written approval before starting. If the paperwork says nothing about this, ask for the sentence to be added. Common extras include longer pipe runs than the site visit suggested, a different valve, a drain connection that needs routing, or a shutoff that was hidden during the visit.

Ask whether the total can change without your signature. If it can, decide whether you are comfortable with that before you commit.

Check what you pay and when

Read the payment schedule line by line. Note what is due at signing, what is due at delivery, and what is due after you have checked the finished work. Be cautious about any arrangement where most of the money is due before equipment arrives. Ask whether the deposit is refundable and under what conditions. Ask who owns the equipment if the job stops partway through.

Know the cancellation terms

Find out whether you can cancel before installation and what it would cost. Ask about restocking charges, fees for a site visit already completed, and fees for custom parts ordered for your home. Confirm that cancellation must be in writing and where the notice should be sent.

What to get in writing before you sign

Ask for four things on paper: the process for approving extra work, the payment schedule, the refund terms, and the cancellation terms. If a seller will not put them in writing, that is a useful signal about how the rest of the project will go. Keep a copy of every version of the quote, including any emails that change a number.