Dielectiric unions

[TravisTea]

Aren't dielectric unions required by code to be installed on this water heater ?
The cold water and hot water copper lines under the houses slab foundation have had 3 leaks in the last several months.

 

[stevemachine]

Are those flex connectors? If they are copper flex connectors they are insulated which has the same effect as dielectric or they should. Any of them I used are insulated. It's kinda hard to tell from the pic. If its an FIP then yeah it should be dielectrics or flex connectors.