Water Filtration System Sizing Calculator

A whole-house filter must pass your peak flow without starving fixtures and hold enough media to serve the water between services. Flow and capacity are two different numbers - both set by how you use water.

Water Filtration System Sizing Calculator matches demand and contaminant to a filter flow, capacity and approximate system size.

• Demand inputs: Daily use plus peak GPM.
• Contaminant aware: Sediment, chlorine, iron and more.
• Technology: Cartridge or backwashing media.
• Capacity: Service life and change cadence.
• Size guide: Housing or tank recommendation.
• Export: Text, CSV or JSON report.

1. Enter daily demand and peak flow.
2. Pick the contaminant and technology.
3. Set the desired service interval.
4. Read the required flow, capacity and size.
5. Export the result if needed.

Example 1. A 300 gal/day house with 10 GPM peak and sediment wants a 10+ GPM filter - a 20-inch cartridge or 12-inch backwashing tank suits, with cartridges changed every few months.

Example 2. A 600 gal/day house with iron needs an oxidizing filter rated above the 15 GPM peak and enough media to run the whole season between backwashes.

• Flow first: Size to peak, not average.
• Capacity planned: Change cadence in advance.
• Technology matched: Right media per contaminant.
• Field ready: Approximate size for ordering.
• Free and private: No uploads, no logging.