Depending on the type of water you use, the pH of the water may change after filtering water with Berkey. Alkaline water is slightly sweeter than pure water. Pollutants increase the acidity in the water, and if you use Berkey water filter, it will filter out those contaminants and raise the alkalinity of the water providing clean drinking water.
That being said, it is possible for water to be alkaline, but it depends on its source and any treatments it has undergone. In general, most tap water has a neutral pH of around 7, but it can vary depending on the minerals and other substances it contains.
Berkey is a brand of water filtration system, and it is not clear how it affects the pH of the water it filters. If you are interested in the pH of your drinking water, it may be best to test it using a water testing kit or by consulting a water treatment professional.