vanlaar said:
Not to cause any trouble or anything, but out of curiosity, how do you explain fish swimming in rivers, lakes, the ocean, etc. which are especially unsuitable for human consumption without filtering? Would you drink the water out of your aquarium? Fish are not susceptible to the same diseases, viruses, or whatever as humans.
No trouble at all. I'm not a biologist, and I'm not a water purity expert, so I could be wrong. But, the reasons I have for recommending not to use the water make sense, both from biological and common sense standpoints. (Again, what I think makes sense could be wrong, but I don't think it is.)
A couple of points: First, which you alluded to, is that Skittyfish's water might just be safe for fish, but not safe for humans to drink (heck, it might even be safe for humans...) I wouldn't want to risk it for with my fish, not to mention I nearly always end up with some tank water on my skin somewhere (hands, at the very least) when I do water changes. So, even if there is some human only pathogen in the water, it isn't good to be the human doing the water changes.
The fish swimming in waters marked as unfit for human consumption are obviously alive, but may not be healthy. Many fish in the wild have internal parasites for most of their life, and may have other deseases that are killing them, but hasn't killed em when we see 'em in the polluted river. My sister (who IS a biologist) has shown me pictures and specimens collected from fish in local (To Maryland, USA) waters that are *not* labeled as unsafe for humans: as an example, the 10-12 inch long worm collected from a live (well, live before they disected it at least) killifish living in a small stream. Anyway, the point is that those fish swimming in unsafe waters may not be doing so hot either.
The biggest reason for boil water notices (as I recall) in flood type situations is the water utility people have lost control of the quality of the input (untreated) water. The output (treated) water system may have flood water leaking into it as well. Flood water quite often contains raw sewage. Raw sewage will lead to raised nitrogen (ammonia, nitrites and nitrates) in the water, at the very least. That alone kinda negates the reason for doing water changes in the first place. More dangerous is runoff from landfills and the like which may contain toxic heavy metals, pesticides, ect. Many of these things can not be eliminated from living things. (They just don't have a mechanism for removing them, so they build up.) The effect from many of these types of pollutants is not immediate, but in lots of cases is deadly or disfiguring.
Another key point: A polluted or unsafe (for humans) body of water most often is still a system that is much more "open" and balanced than the typical aquarium. There is usually *much* less bio-load in any lake or stream, and most bodies of water get regular inputs from some source of more or less clean water. (Rain, underground springs, in rivers that are only polluted downstream of a certain point, ect.) So, you may swim in a certain spot and get sick, but the fish that are 50 feet away in a small area with current might be living in slightly cleaner water. Who knows, there may be a body of water that flooded into the local water supply in Skittyfish's area that even hardy fish cannot live in.
Basically, water utilities should and (usually) do issue boil water or do not use notices at any time they suspect or know the water quality is below whatever level they deem to be unsafe, with minimum standards set by the EPA. (They also issue do not use or boil water notices at any time flood water enter the input (untreated) water supply) The water utility may not even know if the water actually is unsafe, or what in particularl is making the water unsafe. The risks are potentially great (to the fish and the person handling the water) and the benefits are dubious.
In short, better be safe than sorry. I would be much happier at the idea of not changing the water for a week or two than I would be putting water of unknown and probably bad quality into the fish tank.
Whew.. ok, somebody get me a stepladder to get down of my pedestal here... I guess that was almost a rant.