Research and calculator methodology
The publication separates three kinds of information: a claim supported by a read source, a calculation derived from entered values, and an editorial planning assumption. Each can help a homeowner, but they do not carry the same certainty or describe the same scope.
Evidence and its limits
Launch research prioritizes US government and university guidance, standards-body explanations, certification directories, and manufacturer manuals. Brand claims retain their model and product-class limits. A source may support how a system works without establishing that it is better than another system or suitable for a particular home.
AI assisted the research and drafting. The evidence review does not amount to onsite testing, water sampling, or licensed professional review. The editorial policy explains this disclosure and the treatment of commercial claims. A reviewed date marks a research check; volatile prices, certification status, specifications, and local requirements still need confirmation at the buying decision.
Hardness and working capacity
The hardness converter uses 17.1 mg/L per grain per US gallon and treats ppm as approximately equal to mg/L for dilute freshwater. Categories follow the USGS scale with continuous decimal boundaries.
The size calculator multiplies hardness by treated daily gallons, then by the chosen days between cycles. Its upper target adds 20% to demand. This is an editorial load allowance, not a manufacturer reserve instruction. Estimated use is 60 gallons per person daily; seven days is the example interval. Both are assumptions to replace with actual household and model information.
An optional 5-gpg-per-ppm dissolved-iron scenario is disabled by default. It illustrates a possible load adjustment without establishing a universal coefficient or iron-removal capability. Capacity cannot infer rated service flow.
Salt and budget calculations
The salt calculator uses the earlier of capacity exhaustion and a selected calendar interval. It converts average cycles into pounds using the entered salt dose. Capacity must be usable at that same dose; the defaults are independent examples.
The cost calculator sums explicit US editorial scope allowances and separates rental setup from monthly payments. Those amounts are not observed market data. No tool selects an exact model, guarantees local pricing, or replaces the test results and installation scope a supplier needs.