Head height provides sufficient static pressure to produce a net flow rate that is acceptable for target users. In general, higher rate flow rates are more desirable, although there may be sufficiently high flow rates that create the impression that nothing is being done to treat the water.
Head height requirement (static pressure specification) will vary by the design and type of filter element and be provided by the filter element designer.
Net flow rate is measured by the entire volume of untreated water to pass through the filter element.
Notes and exceptions
All things equal, greater head height = greater net flow rate. But head height is constrained by overall product height.
Wall-hung and siphon devices may provide increased head height but may pose challenges to households with limited hanging options.