A modelling concept is presented that enables a quantitative evaluation of transport and natural attenuation processes during bank filtration. The aim is to identify ranges of degradation rates for which bank filtration is effective or ineffective. Such modelling should accompany experimental work, as otherwise the meaning of determined degradation rates for a field situation remains uncertain. The presented concept is a combination of analytical and numerical methods, solving differential equations directly for the steady state. It is implemented using FEMLABs code and demonstrates a typical idealized situation with a single well near a straight bank boundary. The method can be applied to confined, to unconfined and to partially confined/unconfined aquifers and may be extended for applications in more complex situations, including a clogging layer, galleries of pumping and recharge wells, etc.