Read the whole report. The units and sample location matter as much as the numbers.
A water test should help you choose equipment, not leave you guessing. Start by identifying what was measured, how it was reported, and where the sample came from. Then match the results to the problems you are trying to solve.
These results answer different questions
Hardness
Mainly calcium and magnesium. It helps explain scale and soap problems and is a starting point for softener sizing.
Hardness and softener sizingIron
The concentration matters, and so does whether it is dissolved or already oxidized. Clear water at the faucet can still contain iron.
Iron treatment guideManganese
A separate result from magnesium. Manganese can cause dark deposits and affects treatment selection even when iron is the more visible problem.
Manganese treatment guidepH
Describes how acidic or alkaline the water is. It influences treatment performance. It is not a hardness measurement, and it is not the same as alkalinity.
Total dissolved solids
TDS describes the overall dissolved-solids level. A handheld meter estimates it from conductivity. It does not identify individual contaminants or prove water is safe.
RO and dissolved solidsHydrogen sulfide
Relevant to rotten-egg odors. It is different from sulfate. Arrange appropriate sampling with your tester because this gas can be lost from a sample.
Sulfur odor guideCheck the units before entering a number
Hardness may be listed in grains per gallon (gpg) or milligrams per liter as calcium carbonate (mg/L as CaCO₃). Those are different scales. For dilute drinking water, mg/L and ppm are approximately equivalent, but neither is the same as gpg.
Convert only when the report is actually expressing hardness in these units. Do not enter 257 as gpg.
Once hardness is in gpg, use that measured value directly. If a softener will also treat dissolved iron, account for that additional load.
15 gpg hardness and 2 ppm iron
15 + (2 × 4) = 23 gpg compensated hardness. This adds 4 grains per gallon for each ppm of iron the softener will treat. It does not mean the laboratory hardness changed.
Final sizing also considers daily water use, working capacity, salt dose, and household flow. If iron is removed ahead of the softener, use the water conditions reaching the softener. Above 2 ppm iron, we recommend standalone iron treatment.
This example explains sizing demand; it is not an instruction to enter a particular setting into every control valve.
Where was the sample taken?
What is coming in?
A sample before treatment helps identify the job new equipment must do.
What is getting through?
A sample after the equipment helps evaluate its performance.
What are you using?
A sample at the point of use answers a different question from a raw-water sample.
Label each sample location and follow the laboratory’s collection instructions. A metals test, bacterial sample, and treatment-performance check may need different collection methods. Do not substitute a general rinse-and-fill routine for the lab’s directions.
A treatment test is not a complete safety test
A hardness-and-iron test is useful for equipment selection, but it does not screen for every drinking-water concern. EPA recommends annual private-well testing for total coliform bacteria, nitrate, TDS, and pH, with additional testing based on local conditions or changes in water quality. Use a certified drinking-water laboratory and ask your local health department what else is appropriate.
If a result is marked below detection, that means below the method’s reporting limit—not necessarily zero. Keep the lab’s notes and units with the result when comparing equipment specifications.
Turn your results into a system choice
Identify your water source and the problems to treat. Use hardness and any iron reaching the softener in the sizing calculator. For iron, manganese, or sulfur, follow the matching guide above to select a treatment type, then compare the exact model’s water-quality limits and backwash requirements. Check household service flow, dimensions, and installation requirements before ordering.
Choose the guide for your water problem
Already have the results? Use our softener sizing calculator, or check filter backwash requirements before choosing equipment.
Have a question this guide and the product specifications don’t answer? Contact us with that question.