I'm in the 'Do Not Use' zone of West Virginia, so I'm affected by the MCHM CHEMICAL Leak and need to do a partial water change on a freshwater tank. Some of my fish are 16+ years old, and I don't want to lose them.

Since I cannot use water from the sink, would it be better to use bottled drinking water or distilled water? Besides adjusting the pH and temperature, should I do anything else to help fix this?

  • What's in those water buffalos I saw on the news? If that's tap water from somewhere outside the contamination zone, wouldn't that be closer to your regular tap water than anything else? (And good luck weathering this mess -- I hope you're back to normal soon.) Commented Jan 14, 2014 at 22:29
  • That's a good idea! I'll have to see about that. I have some 5 gallon (food grade) buckets that would work a lot better than the gallon jugs. Thanks!
    – Charlene
    Commented Jan 14, 2014 at 23:56

1 Answer 1


I think either one could work for you without harming the fish.

You could use bottled water and treat it like tap water. Since that's basically all it is. The only problem I'd see, is if the company puts in certain minerals to enhance the taste. They could mess with the chemistry of your tank, though probably not noticeably.

On the other hand, distilled water would be low on oxygen content, which you can shake the bottle before using it to help get some of the oxygen back. Either way, I'd probably still put in a bit of tap water conditioner just to be safe. Maybe half of the normal dosage.

I would try to hold out on doing any serious water changes for the time being. Your fish aren't going to be put in mortal danger by doing a water change a week late. Do about a 5-10% water change to pull through this week, and then go back to a 10-20% water change several days after the water has been declared safe.

Other than that, I'm not sure there's anything else you can do for them, just don't expose them to the chemicals.

  • Thanks! I plan to wait at least 2-4 weeks before using the tap water for the fish. They will eventually declare it safe for humans, but will never test for aquariums. I might try to find some place that will test it for them (for a price). Just need to find a reputable place that won't just take the fee and tell me what I want to hear. Anyone know any place? Thanks again!
    – Charlene
    Commented Jan 14, 2014 at 22:15
  • I know Petco will test your water if you take in a sample. I assume Petsmart would do the same. The problem is that I'm not sure any of the test kits for aquarium water are made to catch the types of chemicals that were leaked. I think they're saying that they aren't considering it safe for people until the chemical is only one part per trillion. In that case, it should be safe to use for aquariums.
    – Spidercat
    Commented Jan 14, 2014 at 22:21
  • 2
    The newspaper says it's something called "4-methylcyclohexane methanol" -- definitely not in the API kits that my local Petco uses. But if you can find a fish store in the affected area, you could ask them when they trust the tap to start doing their own water changes again.
    – toxotes
    Commented Jan 14, 2014 at 22:52
  • I have the test kits for aquarium use. Ph, ammonia, nitrites, nitrates, etc... I'd prefer to find someplace that tests it to be safe for drinking. I have no idea what all could be in the water, but don't want to risk the fish, or get it into the silicone tank seals. Maybe someplace that checks the water quality of well water. I just don't trust what the water company and local officials have to say when they won't even discuss the long term effects of MCHM on humans or getting this stuff into our land and ground water.
    – Charlene
    Commented Jan 15, 2014 at 0:09

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