Whole House Filtration Calculator
Size a whole-house water filtration system based on household size, flow demand, water hardness, iron levels, and water source.
Inputs
Results
Total system cost
$4,030.00
≈ 4 smartphones
How to Use This Calculator
- Enter your household size (people) and number of bathrooms to calculate peak flow demand.
- Select your water source: 0 = city/municipal water, 1 = private well (well water needs UV and iron treatment).
- Enter your water hardness in grains per gallon (GPG) from a water test — above 3 GPG warrants a softener.
- Enter iron content in PPM — above 0.3 PPM causes staining and taste issues requiring an iron filter.
- Review Softener Size, Iron Filter, and UV flags to determine which components your system needs.
- Use Total System Cost and Annual Maintenance Cost to plan your whole-house filtration budget.
What each input means
- Household size (people)
- Number of people using water daily (~80 gal/person/day).
- Number of bathrooms
- Determines peak simultaneous flow demand.
- Water source (0=City, 1=Well)
- Well water typically needs UV disinfection and iron removal.
- Water hardness (GPG)
- Grains per gallon. 0-3 = soft, 3-7 = moderate, 7-10 = hard, 10+ = very hard.
- Iron level (PPM)
- Parts per million. Above 0.3 PPM causes staining and taste issues.
What each result means
- Total system cost
- Equipment + professional installation.
- Peak flow demand (GPM)
- Maximum simultaneous water usage.
- Filter rating needed (GPM)
- Filter flow capacity to maintain pressure (1.5x peak).
- System pipe size (in.)
- Main pipe diameter for the filtration loop.
- Daily water usage (gal)
- Estimated daily household water consumption.
- Softener needed?
- 1 = water softener recommended (hardness > 3 GPG).
- Softener size (grains)
- Water softener grain capacity for 7-day regeneration cycle.
- Iron filter needed?
- 1 = iron removal filter recommended (iron > 0.3 PPM).
- UV disinfection needed?
- 1 = UV system recommended (well water).
- Equipment cost
- All filtration components.
- Installation cost
- Professional plumber installation.
- Annual maintenance cost
- Filters, salt, UV bulb replacements per year.
- Pressure drop (PSI)
- Expected pressure loss through the filtration system.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersHousehold size (people) = 4, Number of bathrooms = 2, Water source (0=City, 1=Well) = 0, Water hardness (GPG) = 10 = 5 input(s) provided
- Calculate Total system costTotal system cost = equipmentCost + installationCost4030 = $4,030
- Calculate Peak flow demandPeak flow demand8 = 8
- Calculate Filter rating neededFilter rating needed12 = 12
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.
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