Yield drops of more than 50% are frequent before water well rehabilitations are initiated. Clogged screens show the end product of natural well ageing which can reach up to 4 m in surrounding geological formation.

The more well performance has decreased, the less effective are hydraulic methods alone in securing a sustainable result. Mineral and biological precipitations behind screens, in the annular space and the adjacent aquifer can be removed by chemical agents only.

An incomplete removal of iron(III) enlargens the surface area of incrustations and due to the self-accelerating autocatalysis of iron oxides the production time of well is shortened instead of lengthened. High performance gravel washers inject chemical agents in such depths of pore space which are unreachable by means of any other equipment.

The cost-effectiveness of a chemical rehabilitation is obvious – its expenses will be redeemed within short through the saved energy input.