Small Blue Crystals in drain of Rheem Electric Water Heater

[rtamobile]

I recently purchased a used 2017 Ford Transit 250 SMB. Learning my way around the systems, when draining the water heater, I noticed some small thin blue triangular crystals in the water heater drain. They might be described as blue transparent cooked sugar like you might see in a gourmet dessert. I soaked them overnight in vinegar to see if they would dissolve - but they did not.



I am wondering if they are broken glass from the heater and evidence of a frozen heater event. Any insight or experience? Does the heater need to be replaced?

[carringb]

It’s probably the glass lining of the tank. RV water heaters don’t use a glass lining because of vibration, and use anode rods instead.