In case you get fed up with manually washing the few items you brought along, then you could build your own washing machine in just a couple of minutes. As with many things during vol bivouac, it is free, great fun, and a fine change from all that flying and hiking.
All you need is a river or a stream, and stones to build a crescent moon shaped dam of about one metre wide or so. The width depends on the size and quantity of the items you want to wash. The top of the dam should be above the water level. All water should either flow through or around the dam, not over it. The stones should fit together nicely, otherwise you may find yourself running after your socks when they slip through a hole in the dam.
The crescent moon shape creates a downstream force towards the centre of the dam, preventing your cloths from escaping at the dam's edges. It also minimises the construction effort. To obtain the same effects with a straight dam, it needs to stretch from bank to bank. It could require hours to build, instead of minutes, if the stream is wide.
Put your dirty clothes in the washing machine by dressing them against the dam, below the water level. Do not put in any soap, since nature has great difficulty in digesting soap. Now al you have to do is wait, enjoying the relaxed atmosphere of resting by a stream. Hundreds of cubic metres of clear water will almost effortlessly pass through your clothes, taking away all those nasty smells that take ages to get rid of when washing them by hand.
All seems perfect, until you realise that your washing machine is not environmentally friendly, according to the experts in Brussels. It consumes too much water. Way too much. The number describing the water consumption will not even fit on the mandatory energy label (it has to be expressed in litres, otherwise buyers will be even more confused than they already are). You briefly consider the disposal of your washing machine in an environmentally respectful manner by bringing the stones to the local déchetterie, when you suddenly realise that the nature is causing this particular wasteful behaviour all by herself, without even having submitted the proper compliance documents.
Now wait a minute! If we would like to discuss this issue with somebody who knows a lot about the environment, then mother nature is the natural expert to talk to. So, she probably has a good reason for her behaviour and you decide not to bother. It would not be the first time that Brussels is totally unaware of something that is useful, practical, cheap, and therefore absolutely not in accordance with their regulations, such as a light bulb or a natural washing machine.
A more important drawback is that your washing machine will not work that well during and after (heavy) rainfall. The rain washes the sky and the earth. The resulting dirt and debris is carried away by the streams and rivers, polluting your clothing in the washing machine. So, plan your washing carefully. Do not use a specific day of the week, such as Monday, since it might rain that day or have rained the day before.
The enthusiastic expert probably has already noticed that the above washing machine can be improved. For instance, it could be combined with a jacuzzi in order to create a whirling motion that is even more effective in getting rid of the dirt.
I would not dare interfere with your creativity, so I will refrain from describing further improvements. Just let me finish by giving you an alternative washing machine in case you do not have much time or lack the energy to build one.
Put a stone in your sock (or any other item you like to wash) and simply let it sink to the bottom of the stream. Make sure the stone has enough weight to prevent your sock from floating downstream, and that the stream's deepness does not unnecessarily complicate the recovery of your clothes. Since the water will flow around your clothes rather than through it, this washing machine is less effective than the previous one. However, it has a construction time of seconds only. In practice, I have not found that much difference in the final result, except that building a damn is more fun.