I want to save space and install a wash basin above a front loading washing machine? Will there be any problems? Will the wash basin be too high for persons of average height?
unfortunately it will be to high you will need at least a foot of space below the sink for drainage and pipe feeds and the sink depth you could place a work surface above and move you sink elsewhere
I think you must REALLY want to save space. You will have to have room under for the drain pipes.You will likely have to use a step. EDIT ******************* They make compact wash basins which may meet your needs. See websites below
If the plumbing can be done under the appropriate regulations then it can be done. You should know by looking at it if it is going to be too high for the user. Also speaking with a reputable plumber or going to a specialist kitchen/bathroom centre who supplies sinks can be helpful as they may suggest many alternatives to you or different methods of plumbing.