Welcome to the Forums and the world of Vintage Overlander ownership!
Originally Posted by sonyamontana
Hi Friends! We are the proud new owners of a 1968
Overlander 26T Airstream. We are now calling it our sole home for the next few months while our home is being built.
Question: we filled up our water tank to 1/2 full - when we do dishes in our kitchen sink the water backs up in the tub and toilet. What does this mean and what should we check? I can't imagine the holding tank is full after 5 days of doing light dish duty. Can you help?
Unless your '68 Overlander has been modified from its original configuration, it does not have a gray water tank (where the drains for sinks and bathtub would empty), rather the coach was designed with the intent of draining gray water on the ground. My guess is that you have been filling the black tank with a mixture of toilet waste along with your gray water resulting in the backup that you mention. Thetford makes a termination cap for the dump valve that allows the gray water to be drained into a portable tank through a short length of garden hose (these tanks are often called a "blue boy") that can be emptied into an appropriate drain. If your coach has been modified and now has a gray water tank, it is entirely possible that you are completely filling the tank in the time frame that you mention as the gray water tanks that are often retrofitted into Vintage Airstreams are often quite small and need frequent dumping.
Good luck with your investigation!