Most treatment quotes describe the equipment and the install. Fewer describe what happens when the water still does not look, taste, or test the way you were told it would. Before you sign, get the answer in writing, because once the crew leaves, the contract is the only thing you can point to.
Define the problem in measurable terms
Start with the reason you are buying. If the complaint is staining, the target is a stain-free result on a named source, not better water. If the complaint is taste or odor, write down the test or description you are relying on. A retest clause only works when both sides agree on what fixed means.
Ask who retests, with what, and when
Ask whether the provider retests, whether they use a certified lab or a field kit, and whether you can watch the sample being taken. Ask how soon after install the test happens and whether the system needs a settling period first. Ask whether the retest uses the same parameters as your baseline test, so you are comparing like with like.
Ask who pays for the adjustment
If the result misses, the next question is what happens. Ask whether the provider adjusts settings, changes media, or adds a stage, and whether any of that is included or billed separately. Get the time limit for reporting a miss, and the route for disputing a result, in writing.
Read the clause, not the sales line
A phrase like satisfaction guaranteed does not tell you who acts or in what order. Look for a named remedy, a deadline, and a named party responsible. If a provider cannot describe the steps in plain words, treat that as information. Our methodology page explains how we set up our comparison criteria, which can help you decide which questions belong on your own list.