Pinnacle™ or Pinnacle Plus™ reverse osmosis filters work
well between 77º and 113º Fahrenheit (25º–45º Celsius).
Reverse osmosis membranes work best using colder water. The colder the
source water is the higher the pressure and the lower the flow will be
through the reverse osmosis membrane. As such, more impurities or Total
Dissolved Solid (TDS) are removed from the source water. The higher the
temperature of the source water is the lower the pressure and higher
the flow will be through the reverse osmosis membrane. As such, more
impurities are able to pass through the filter. The difference is minimal
in any case but worthwhile noting.