I don't know if there are any guarantees with liquid cooling and it would depend on the conditions (sunlight exposure, case heat etc) as to how quick the tubing breaks down. I'd imagine they would go several years without issue and may develop a pump issue before leaking. Can't really say on any of them for 4-5 years (I know of people who keep custom cooling loops this long but with upgrades or changes here and there and maintain it - I think the kraken is maintenance free and can't be flushed regularly). By the time it gives out (pump or leakage) you'll probably want to be upgrading it anyway.