When you are attached to the campground water or thru the pump of the trailer? If it's your water, are you hooked up to a well or the town water? Dirty brown I would think is to much Iron in your water which your sinks and toilet would turn brown. Could that be the case?
Yah that's the problem when you are hooked up to the water. It is the same problem like when you don't use the faucets enough at home. When you do turn them on, they are rusty because the water has sat in the pipes.
Same idea. Plus the water itself may be off color which is normal for some cities. There are RV and trailer filters out there to remove or limit the iron oxide.