Originally Posted By: jpeck This post was automatically imported from our archived forum.
On houses I inspect, I point that out to my client and tell them that it should be fully supported, then when they ask “How far can it hang over and not be a problem?”, I tell them that if at least 2/3 to 3/4 of the water heater is on the stand, and the water heater does not lean forward, there is little likelihood of the water heater tipping over, because much more than half the weight is on the stand and not much is over hanging it. Then I tell them “Mine has been that way since I replaced my water heater about 10 years ago.”
That usually makes them smile and re-assures them that it should not be a problem if they leave it. But it is still in my report that it is overhanging its support and caution that it "could" tip over under the right (wrong) conditions.
Now, if we were in a seismic area, I would not do it.
Down here, though, if the hurricane blows that over, I have worse problems, because my water heater is INSIDE. 
Looks like that is on a concrete block built-up stand. If it is 22" diameter, then 7" is overhang about 1/3.
Here is what I am using to figure the 1/3: water heater is 22" (give or take) and has 2"-3" insulation all around inside the outer tank cover. That means the water tank itself is about 16"-18" diameter. 1/3 of that is 5" to 6", plus 2" to 3" of insulation, means that 7" of overhang is about 4" to 5" of tank overhanging the support, or right at about 1/3. The maximum I would be comfortable with -*in MY house*. I use a greater safety margin for the houses of others, after all, I am not going to sue myself if something happens -I'll just go "Oh $hit. I KNEW that might happen", as my wife beats me over the head with a broom saying "You idiot, then why did you do it?".