On the other hand, allowing people to feed their sweet addictions only re-enforces and desensitizates them further. So while you are probably safe drinking ungodly amounts of aspartame water, you won't find equivalent substitutes for sugar in other foods and you might suffer rebound consumption there, perhaps to a much higher total caloric intake versus just drinking sugary water in moderation.

Another thing to watch out for is caffeine input which is often associated with sweetened drinks. Caffeine is a diuretic and you will see yourself drinking can after can of diet coke while not quite quenching your thirst or properly hydrating yourself. This is documented to lead to intense muscle pain and unexplained migraines for people who do physical work and abuse these types of drinks, and can't be good for your kidneys long term, even under the assumption that sweeteners are 100% safe.

Overall, just drink plenty of water and use everything else in moderation seems like a solid advice.