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Water Comparison Table

Last Updated: 11/6/06

This table shows the various types of water that are available for use for aquariums, ponds, and drinking (animals and people).

Visit my page on water for more information.

When I refer to water being tested, I am referring to knowing the pH, hardness, and alkalinity and finding that those values are fine for the animals that one is keeping. When I refer to complete testing, that also includes testing for various organic and inorganic contaminants/toxins as well as bacteria. Dechlorination refers to the removal of any chlorine or chloramines added by the water companies by the use of a dechlorinator (sodium thiosulfate is most common). Dechlorinators may also be called water conditioners.

Contact me if you have any additions or corrections for this table.


Attribute Tap/City Water Well Water Spring Water Bottled (Unlabled Tap Source) Water Distilled Water Mineral Water Reverse Osmosis Water Carbonated/Seltzer Water Rain Water
Useable for Aquariums Yes, if tested and dechlorinated Yes, if tested Yes, if tested Yes, if tested and possibly dechlorinated Never by itself, may be mixed with other water No Not usually by itself, may be mixed with other water No Sometimes, if tested, usually mixed with other water
Useable for Ponds Yes, if tested and dechlorinated Yes, if tested Not economically feasible Not economically feasible No No No No Nature will add some for you!
Potable (animals and people can drink it) Yes, if tested, better to filter with carbon to remove chlorine Yes, if tested Yes Yes No Humans only No Humans only Not ideal but okay in most cases
Other Uses Cleaning, many others Cleaning, many others N/A N/A Sterile cleaning, growing out certain crustaceans like triops N/A N/A N/A Watering plants
pH Tendencies Varies, usually buffered to pH 7 to 8 Varies, some wells are about pH 6 to 7, others are 8 to 9 Usually 6 to 7 Varies, usually buffered to pH 7 to 8 Unstable, technically pH near 7 but a stable reading cannot be made Perhaps 8-10 May be unstable, perhaps pH 6 to 7 Acidic, pH 2 to 5 depending on carbonation level Varies, tends to run acidic, pH 5 to 7
Hardness Tendencies (more hard = more minerals and ions) Various on location, often moderate to high hardness Various on location, some wells are very soft, others are very hard Low Various based on source None High Low (nearly none) Varies Low
Alkalinity/pH Stability Moderate Varies from low to high based on the area Low Moderate Very Low High Low Low (once aerated to remove the carbon dioxide, it is more stable) Low
Economical Cost Low Low Moderate Moderate Moderate Moderate High Moderate Free
Chlorination Level High None None Moderate to High None Usually None None Usually None None
Fluorination Level High None None Low to Moderate (it may dissipate, not stable) None Usually None None Usually None None
Carbonation Level Low Low None None None Usually None None High None
Oxygen Level (aerate water!) Moderate Low to Moderate Moderate Moderate Low Low Low Very Low Low

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