Most softener conversations start and end with hardness. The seller tests for hardness, names a grain number, and recommends a unit. But if your water also carries dissolved iron or manganese, a standard softener can struggle with it, and the damage often shows up months later as stained fixtures, a fouled resin bed, or a claim that the warranty will not cover. Before you accept any quote, you should know what else is in the water.
Ask for the full lab report, not a summary
Ask for the original laboratory report, with the name of the lab, the date the sample was taken, and the list of what was measured. A line on a sales form that says 'water tested, hard' does not tell you whether iron, manganese, or hydrogen sulfide was checked at all. If the company used a home test kit, ask which parameters the kit covers and whether it reads iron at all. A kit that only reads hardness will be silent on the problem you most need to see.
Ask where the sample was taken. It should come from a tap that reflects the water the softener would treat, ideally before any existing filter or treatment, so the numbers describe the real supply. If you are on a private well, ask whether the sample came from the well itself or from somewhere along the line where the water may have changed.
Ask what the numbers mean for the unit
Once you have the report, ask the company to walk you through each line that matters for the equipment. Specifically, ask:
Does the report show iron, manganese, or both? If yes, at what level, and does the company's own product literature list a limit for that level? Put the number they quote next to the number in the report and check that they match.
Does the water smell of rotten eggs, or does it stain sinks and laundry a rusty or dark color? Those observations, which the lab report may not capture, should be written into the notes the seller takes at the visit.
If iron or manganese is above what the softener is rated to handle, what do they recommend? Common answers involve a separate pretreatment filter ahead of the softener, a different media, or a different system altogether. Each of those is a separate piece of equipment, so ask whether it is in the quote. If the seller says the softener alone will handle it, ask them to put that in writing with the specific model and the limit it is rated for.
Ask how the warranty treats iron
Many warranties exclude damage caused by water conditions outside the unit's stated limits. Ask the seller to point to the exact clause that covers iron or manganese fouling, and read it before you sign. If the clause says the warranty is void when the water exceeds a stated level, you need to know whether your report is below that level, and whether the company will re-test if the report is old or the supply has changed. The clause layout and what it excludes are covered in more detail in our guide on warranty exclusions, and you can compare how companies are evaluated in our rating method.
What to do with the answers
If the seller produced a real lab report, answered each question with a specific reference, and put any pretreatment in the quote as its own line, you have a comparable offer. If the seller could not produce a report, or said iron is 'not a concern' without showing a number, treat that as an open question and get the test done before you decide. A few dollars and a few days spent on a lab test are cheaper than replacing a resin bed or a water heater that has been stained from the inside.