The flow rate of an Ultimate Star Filter® gravity filter may be surprising: it is intentionally fast yet controlled. Contrary to a common belief, a high flow rate does not imply poor filtration. Efficiency primarily depends on the actual contact time between the water and the filter media, as well as the internal design of the filter.

Short answer

A new Ultimate Star Filter® typically delivers between 12 and 16 liters per hour per pair of filters, then the flow rate gradually decreases with use. This flow is intentionally designed to provide an optimal balance between filtration efficiency and practical usability.

Why a fast flow can still be highly effective

In gravity filtration, water passes through the media without mechanical pressure. What truly determines efficiency is not apparent speed, but the time during which water interacts with the active materials.

The Ultimate Star Filter® multi-layer design — high-quality activated carbons, specific materials, and membrane — provides this necessary contact time while maintaining a practical daily flow rate.

Performance therefore relies not on slowness, but on the quality of materials and internal architecture.

Typical observed flow rates

These values are indicative and may vary depending on water quality, temperature, maintenance, and usage conditions.

Why flow decreases over time

The gradual decrease in flow is normal: it reflects pore fouling and progressive saturation of active sites in the filter media. This phenomenon is a useful indicator of filter condition, not a failure.

The most reliable proof: independent testing

Filter performance should not be judged by apparent speed, but by its ability to retain contaminants over time. Ultimate Star Filter® cartridges have been tested by independent laboratories throughout their recommended lifespan.

These analyses provide the only objective reference for evaluating real filtration performance.

Further reading