Here are some useful specifications:
Katadyn Drip Filter
0.2 micron ceramic depth filter (Note: This is the ABSOLUTE filtration specification, NOT the Nominal filtration rating.)
British Berkefeld Big Berkey
With filtration rating efficiencies of >98% down to 0.2 microns >99.9% at 0.5 microns >99.99% at 0.9 microns (Spectrum Labs).
Note: Berkefeld’s ABSOLUTE filtration specification is 0.9 microns. (See the above line.)
I ‘ve watched the PR advertisements regarding Berkefeld and just sat there shaking my head. I was sent some Berkefeld filter replacements which were touted as equal to Katadyn’s but a much better price. NOT! When I read the spec’s on the filter, I sent them back and bought Katadyn’s. (Actually, it’s just as cheap to buy a new complete drip unit as to buy replacement filters. Well, within $15 bucks anyway.) Don’t get me wrong, Berkey’s do filter …..but Katadyn does it a lot better.
Oh, I tried the Gravidyn filter element by Katadyn, which has the carbon filter built in but they are to be changed every six months. Not worth the cost for me unless I lived in a city. With the Ceradyn filters, you use them until they are worn out. That’s a lot better for a long run need and mine generally last 6 years.
I should mention that when you buy a complete new Katadyn replacement unit, you still have the old one which wasn’t totally useless. Eventually you end up with ones you could give to the needy neighbors who could get by on it. Just a pet peeve where I think the American consumer is being misled. Gosh, like that’s uncommon, huh? I hope that Berkefeld isn’t supporting your blog 😉 – The Army Aviator