Washing clothes is always difficult when you are travelling. It was fine in Rijswijk with a washing machine. And if you stay in well equipped places then there are services that cater for your laundry needs. However in Granada, Cordoba and Madrid I have done the wash-in-the-hand-basin routine (though that was complicated in Cordoba because there was no plug, so I stuffed the plughole with tissues - result my washing came out covered with those incredibly annoying tiny bits of tissue! I should add that I didn't stuff the tissues down the plughole - just to cover the surface of the opening).
I brought some washing powder with me but found I can't use it because it irritates my hands badly. So this morning, in order to deal to a badly-in-need-of-a-wash pair of trousers and top I dropped then on the floor of the shower and 'trod' them like grapes! Worked OK.