Dear Ms. Tam, i would ...
Published by Thomas Junger, Manager at Stadtwerke Memmingen (public water utility) and proprietor of "TrinkwasserConsult"
Dear Ms. Tam,
i would recommend a manual processing first to remove all the visuable dirt and as a second step a surface-desinfektion with hydrogen peroxide solution. This requires several technical equipment of the tanks like a drain, two chambers for non-interrupted water-supply and several more. In many cases, cleanings are not done because those responsible have no idea how to handle the process without getting stress. So my recommendation is -> first chance the technical equipment into something workable and then second do the cleaning and desinfection without getting in trouble with the residents.