Cracked Suburban water tank

Contrary to popular opinion a Suburban water tank which is porcelain lined steel is much less likely to split open than an Atwood aluminum tank but can hairline split as yours has. Since this is just a hairline crack and it is a steel tank you don't have much to lose other than a few $$ by having a welder see if he can repair this crack. However, if you do decide to replace it you'll likely have to replace the entire water heater because AFAIK Suburban doesn't offer just the tank itself, whereas Atwood does, I suspect because Atwood aluminum tank splitting is so common. While camping a couple of weeks ago I helped a friend remove his own leaking Atwood WH but because it turned out to be a hairline crack around the water pressure relief valve he's going to have the tank aluminum welded rather than replace it ... he got lucky!

I've owned both brands and although both work well for the intended purpose the Atwood in my experience offers a much faster recovery time. However, they each require an entirely different sized cutout in the trailer sidewall so if you do replace your Suburban do so with another Suburban as you'd find retrofitting an Atwood into a cutout it wasn't designed to fit a real PITA.