How many of you out there drink tap water? My family has a lot of health issues so we gave that up a long time ago. We drink filtered water and so my rabbits.
Some water systems have unbalanced pH levels and are high in chlorine. Sometimes the water is the culprit if one of your rabbit unexpectedly dies.
No matter what kind - or quality - of water you are giving to your rabbits (unless you can provide something better), keep them on it. I've heard that a sudden change in water, just like a sudden change in diet, can cause digestive upsets.
Always make sure your rabbit has water constantly available. If rabbits get too thirsty, they won't eat. If they don't get water, they will die of not only hydration but also starvation.