I used the bottled "Spring Water" not Distilled or Drinking Water for a while because I had a Very High Nitrate Level but only to mix about 50% into tap water, but I found out this is not a good idea as it does not appear to be a good thing for the fish in the long run. It is too hard to get a constant mix and the use of Amquel+ in the water to remove the Nitrates was just as effective. There should be no way you would consider the use of all of your water as the fish and plants do benefit from some of the properties found in water that is not processed in this manner, and processed it is. Plus if you have shellfish like shrimp or snails they will appreciate the calcium levels that tap water can have that the bottled water will not contain.
It is just not a good idea unless there is a definite reason why the city water cannot or should not be used for human consumption, in which case, you have a much larger problem than what to fill the tank with, me thinks.
Welcome to Fishlore.com. It is a great site where we do try to answer the questions of those of us who keep fish and care for our little friends. There are some great people here and I hope your experience here is as pleasant as mine has been. Again, welcome.
Rose
