V29, in response to your specific question, that white crusty material is an assortment of compounds formed as the anode oxidizes. To work, an anode must be higher on the galvanic scale than the material it is protecting. i.e., typically magnesium or aluminum to protect steel, or magnesium to protect aluminum.
Those oxides precipitate into your (our) water heater and are the cause of that milky look when we drain and flush. They also flow out of our faucets, but are usually diluted to a point that they are not noticed.
Your water heater should have one, or more, check valves to prevent water heater contents from back flowing into your potable water tank. So, no worries there.
I have all the respect in the world for our fellow forum members, many of whom have provided us with sound, slap your forehead advice, and follow the RVGeeks on YouTube, but I am of a different, decidedly minority view on this subject. Similar to Galileo!
This knuckle-dragging old Main Space Engineer would offer clarification by way of the American Galvanizers Association
https://galvanizeit.com and their galvanic reactivity chart.
We have an OEM aluminum clad Atwood WH. We have always maintained it with a magnesium anode. 16 years on, camera inspection shows it is still sound. (Although we did replace both check valves.) We followed the same regimen on both our Catalina sloops.
Fair Winds and Following Seas