here in Maine.. They make custom welded plastic tanks and do tremendous work. If they are good enough for a guy like Cabot Lyman (Lyman-Morse) I suspect you'll be fine. They specialize in welded plastic fire truck bodies and are the #1 in that industry. Last time I was there they were pressure testing a 30,000 gallon welded plastic tank... Dinky little boat tanks are nothing for these guys...