Why are Berkey Water Filters banned in California?

They aren't.

Here are all the Berkey water filter systems available for purchase and shipping to California.  It's not true to say Berkey are banned in California.

The following are Berkey California approved:  Travel Berkey, Berkey Light, Go Berkey Kit and Sport Berkey.

The tests Berkey has conducted are much more rigorous than those required by NSF for the certifications mandated by the state of California.

In the end, Berkey has concluded that the additional taxes, certifications and red tape have created too large of a barrier for our firm to offer systems such as the Big, Royal, Crown and Imperial.