In some hotels and other kinds of accommodation including hostels and I believe even campgrounds there is a rule against hand washing your laundry in the sink or handbasin, or in your room. I'm sure I've come across this in multiple countries.
Now one of the tips for saving money when travelling on a budget is to wash your own clothes by hand. Especially when combined with tips for travelling with minimal luggage which include wearing the same clothes over and over by washing them every night in your hotel room. (I believe Rolf Potts advocated this in his no-baggage round-the-world challenge.)
Do we know the reason(s) for this rule?
Is it unhygienic? Does it cause problems with the drains? Does it stain the sinks? Have people gotten sick from preparing food in sinks used for clothes washing?
I'm pretty sure it can't be just to get guests to pay for their laundry service as I'm pretty sure I've seen this even in places that don't offer a laundry service. For instance I think I've even seen it at campgrounds.
Yes I know some places offer a special sink for hand-washing, as does the hostel I currently work at.
If anybody knows what I'm talking about and has a photo of such a sign or rule to contribute then please add it. Whether you know the answer or not (-: