An arrangement for connecting a first drain system, such as a rainwater drain system, and a French drain system, the arrangement comprising: an inspection well device suitable to be connected between the first drain system and the French drain system for enabling, in an installed state of the arrangement, the installation of said French drain system at least partly under said first drain system,so that said first drain system and said French drain system remain as separate systems, said arrangement further comprising a French drain inspection well connectible to said French drain system, wherein said inspection well device comprising: a bottom part for preventing unwanted water and dirties from entering into said French drain, wherein the arrangement further comprising an inspection well, and a number of outlets formed to the inspection well for connection to pipelines of the first drain system, said inspection well device further comprising a tube part protruding from said bottom part for, in an installed state of the arrangement, inspecting and cleaning said French drain, wherein the height of the tube part is selected to be higher than any of the outlets, wherein said outlets are arranged in different heights, wherein said inspection well device is arranged inside an inspection well, wherein at least said bottom part and at least said tube part are arranged at least partly inside said inspection well. an inspection well device suitable to be connected between the first drain system and the French drain system for enabling, in an installed state of the arrangement, the installation of said French drain system at least partly under said first drain system,so that said first drain system and said French drain system remain as separate systems, said arrangement further comprising a French drain inspection well connectible to said French drain system, wherein said inspection well device comprising: a bottom part for preventing unwanted water and dirties from entering into said French drain, wherein the arrangement further comprising an inspection well, and a number of outlets formed to the inspection well for connection to pipelines of the first drain system, said inspection well device further comprising a tube part protruding from said bottom part for, in an installed state of the arrangement, inspecting and cleaning said French drain, wherein the height of the tube part is selected to be higher than any of the outlets, wherein said outlets are arranged in different heights, wherein said inspection well device is arranged inside an inspection well, wherein at least said bottom part and at least said tube part are arranged at least partly inside said inspection well. a bottom part for preventing unwanted water and dirties from entering into said French drain, wherein the arrangement further comprising an inspection well, and a number of outlets formed to the inspection well for connection to pipelines of the first drain system, said inspection well device further comprising a tube part protruding from said bottom part for, in an installed state of the arrangement, inspecting and cleaning said French drain, wherein the height of the tube part is selected to be higher than any of the outlets, wherein said outlets are arranged in different heights, wherein said inspection well device is arranged inside an inspection well, wherein at least said bottom part and at least said tube part are arranged at least partly inside said inspection well.