Abstract The bed depth filtration unit (a rapid sand filter) shown in the next section (pictures) was used for water purification. Filtration consisted of the transport and attachment of suspended objects (CaCO3). The flow through the porous media obeyed Darcy's law which states that in all cases of filtration the flow is in the laminar range and that the pressure drop is governend by the flow rate. The initial head losses were calculated using the Carmen-Kozeny equation [1].