Most homeowners who get more than one water treatment quote end up comparing totals. The total is the last thing to compare. Two quotes can carry the same headline price and still describe different equipment, different installation work, and different promises after the crew leaves. Before you weigh one bid against another, rebuild all of them on a single page so the differences are visible.
Start with the same starting facts
Give every provider the same information. Write down the test results you already have, or state that you have none. Note the number of people in the house, the approximate number of bathrooms, whether any fixtures use water heavily, and where the main water line enters the home. Include the location you want the equipment placed, such as a basement, utility room, or garage, and whether it has a floor drain or a nearby drain line.
Ask each provider which water test they used to choose their equipment. A provider who cannot name a test, or who recommends equipment before asking what is in your water, has skipped a step that every other bid depends on. If a provider wants to run its own test, ask whether the results will be given to you in writing and whether you can share them with the other providers.
Build the comparison grid
Make a simple table with the providers across the top and these rows down the side. Fill each cell from the written quote, not from what the salesperson said on the phone.
First, the equipment: the make and model, the rated capacity, and the stated basis for that capacity, such as the hardness figure or contaminant level the sizing assumes. Second, the installation scope: the plumbing connections, bypass or shutoff valves, the drain connection, electrical work if any, and startup. Third, what is excluded: permit fees, old equipment removal, repair of drywall or flooring, and any work the quote assumes you will handle. Fourth, the consumables: salt, filters, cartridges, resin, or lamps, with the replacement schedule the provider expects. Fifth, the warranty: the length for the tank or unit, the length for parts, the length for labor, and who files a claim. Sixth, any maintenance agreement, its renewal terms, and what it covers.
Leave a cell blank if a quote says nothing about that row. A blank cell is a question to send back to the provider, not a point in favor of the quote that stays silent.
Read the gaps before the totals
When the totals differ, look for the reason in the grid. A lower price often comes from a smaller unit, a narrower installation scope, or an exclusion that moves a cost to you later. A higher price may include a larger capacity, a longer warranty, or work that the cheaper quote leaves out. Neither is automatically the better deal. Ask each provider to explain, in writing, why its sizing or scope differs from the others.
Watch for quotes that name a capacity without stating the assumption behind it. If one provider sizes the equipment for a daily use figure and another sizes it for a peak-flow figure, the two numbers cannot be compared directly. Ask each to restate its sizing using the same inputs you gave them.
Ask the questions that expose the rest
Send the same written questions to every provider and keep the replies together. Ask who will perform the installation, whether that person is an employee or a subcontractor, and who will answer the phone after the job is finished. Ask what happens if the equipment underperforms in the first month, and what the process is for a warranty claim. Ask for the names of the parts manufacturer and the distributor, so you can check warranty terms directly if you need to.
Check whether each provider will accept a written scope change before work starts and how it will price any extra work it discovers on site. The terms for changes matter as much as the quoted price, because the bid you sign is the starting point for any later adjustment.
Decide with the grid in front of you
Once the grid is complete, rank the providers on the rows that matter most to your house: capacity that fits your test results, installation work that matches your plumbing, clear exclusions, consumable costs you can sustain, and warranty terms you can enforce. Then compare the totals. The total should be the final check, not the starting point.
For guidance on how this publication evaluates providers, see the Review Methodology and Editorial Criteria. For ratings of providers serving the St. Louis area, see the St. Louis Water Reviews ratings page.