Iron  with  special  coating  is  used  for  manufacturing of in-wall concealed  cisterns with metal frames to prevent rusting, then frames are  colored  with  special  paint and put in special ovens with 210 degree celsius.

Tanks for water are made of copolymer. Tubes and branch pipes are of polypropylene.  All  in-wall  concealed   cisterns  with  metal frames withstand a load of 450 kg.