The Black Berkey® water filters used in Berkey® purification systems are fully capable of filtering rainwater.

However, certain precautions must be taken. For example, make sure that there is no contamination by a specific pollutant that would be missing from the test results performed by Berkey®. Also, be careful to minimize contact of the water with any animal feces (birds, squirrels, etc.) or chemicals used on the roof. The water should be pre-filtered before entering the purifier to avoid excessive suspended solids, which would clog the filters more quickly and require frequent cleaning.

Some of our customers have built rainwater filtration systems with a multi-stage collection process (up to 5 for some systems) and equipped with several Black Berkey® filter elements (from 4 to 8). The water is filtered in successive stages and stored in suitable containers.

Even if the Black Berkey® elements are water purifiers, it is nevertheless recommended, in this type of use and if for example a high contamination by E-Coli is suspected, to add a few drops of disinfectant (unscented) based on chlorine, at the first stage of filtration.

See also this topic on filtering water from a source other than the tap.