Five inputs decide size
- Peak simultaneous demand in gallons per minute.
- Static and dynamic pressure at the installation point.
- Water chemistry, sediment load, and the media's feed-water limits.
- Pipe and port size plus the manufacturer's pressure-drop data.
- Wall width, depth, vertical service clearance, drainage during filter changes, power, and bypass access.
Rated flow is not household flow
A headline ‘15 GPM’ may be a maximum operating value rather than a certified service flow at a stated pressure drop. Ask for the pressure-drop curve, define the household's simultaneous demand, and include other equipment in the train. A one-inch port does not guarantee one-inch-system performance.
Design for the filter change
- Measure the assembled width, depth, and height.
- Add the manual's required clearance below housings or above media tanks.
- Provide isolation and a code-compliant bypass where appropriate.
- Plan where water and the weight of a wet cartridge go during service.
- Protect equipment from freezing, heat, sunlight, contamination, and unsupported pipe loads.
When professional sizing matters most
- Private-well pumps and pressure tanks.
- Iron, manganese, sulfur, or microbial treatment.
- Multiple devices in series.
- Low pressure, high peak demand, or large homes.
- Drain, electrical, grounding, backflow, permit, or local-code questions.
Sources
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