Yellow water in your cabin sink.
 

I saw a few videos on youtube of passengers that showed yellow water running from the sinks in their cabins from 3 different cruise lines and they were not happy about it. What is that from?

Rust? Iron content? Algae? Disinfectant? Cedar water, common in some places in the south, will turn your drinking water (harmlessly) brownish, your laundry water potentially not so harmlessly.

What do the cruise lines say? Did anyone bring any of this back to have tested?

I keep telling Grandpa that the low white thing is the toilet! The one on the wall is the sink!

Gee thanks for the help, sonny boy

I never asked them. I found it interesting yet alarming that it appeared on three different cruise ships with three different cruise lines so I eventually thought that it may have been some kind of chemical that the engineers added to sanitize the water system on the ships and you were suppose to run the tap until it ran clear, but I wasn't sure.

The cruise lines were Carnival, Costa Cruise, and I think RCCL. All on youtube under "cruise yellow water"