Is Distilled Water Good for Aquarium Tanks?

“Distilled water is pure and should, therefore, be better for my fish and plants.”


“Is it safe to use distilled water for a fish tank”

The difference between all water types and what they are good for

Distilled (DI) water

Impurities that boil equal to or below the boiling point of water are likely to pass over. This includes organic compounds like benzene and toluene. If such impurities are not removed prior to distillation, then they are likely to be found in the purified product (1).

The distillation process effectively removes pesticides and chlorination agents.

Distilled water is water that has been vaporized and then condensed back into liquid form. This process separates the water from impurities that do not boil at the same level as water. This purification method allows the water to reach 0 ppm, however, there are exceptions

Reverse osmosis (RO) water

In reverse osmosis, water is filtered using a semi-permeable membrane that blocks anything bigger than water molecules. This method removes 90 to 99% of impurities like calcium, iron, fluoride, lead, manganese, and salt.

Osmosis refers to the process by which water molecules from a less concentrated solution pass through a semi-permeable membrane to a more concentrated solution.

Reverse osmosis slightly affects water pH.

Purified water

Purification is attained through various methods like distillation, reverse osmosis, and carbon filtering.

Depending on the method being used, water purification can remove from water inorganic ions, organic compounds, bacteria, endotoxins and nucleases, gases and other particulates, (2).

Mineral water

Mineral water is water sourced from mineral springs. It contains various minerals and may be suitable for your aquarium, (3). However, we do not recommend you use mineral water.

Depending on the size of your aquarium, bottled water may not be a practical and cost-efficient choice.

Furthermore, the mineral content of bottled water may not be sufficient to maintain the health of your fish on the long-run.

We recommend you use bottled mineral water during emergencies only.


Springwater is collected from various sources and may not always be the right choice for your aquarium.

Depending on the spring from which it is collected, the mineral content of the water may not be adequate for you aquarium.

Like mineral water, spring water is typically bottled. For the same reason mentioned above, this may not be a practical or cost-efficient choice.

What is the water distillation process?

When should I use distilled (DI) water?

Fish and plants require mineralized water for growth, metabolic functioning, and cycling. Therefore, distilled water can be detrimental to aquarium life if used during water changes.

Therefore, distilled water should only be used to replace water that has evaporated from your aquarium. This will not affect the mineral content of your aquarium and will promote a stable environment for your fish.

Since distilled water lacks minerals it should not be used during water changes. Replacing the water with distilled water would essentially remove beneficial minerals from your aquarium.

If you’d like to use distilled water in your water changes, the water should first be remineralized.

This is a method for fishkeepers, who want to maintain the purity of their water.

Purified water like distilled and reverse osmosis can be remineralized using products like Seachem Equilibrium. Products such as this one will add the necessary minerals that your fish and plants need.

Distilled water can be used in conjunction with tap water during water changes in order to reduce hardness.

Remineralization helps maintain the balance and stability of your aquarium.

When should distilled (DI) water be avoided?

As mentioned earlier, distilled water should not be used during water changes.

Fish and plants need minerals in order to be healthy. Such minerals include calcium, iron, and magnesium.

These mineralize not only help fish stay healthy, but they also stabilize pH levels.

How to remineralize distilled water for a fish tank

Remineralizing purified water is simple. Minerals can be added to the water with products like Seachem Equilibrium, which contains calcium, magnesium, and potassium salts.

Can you use distilled water for saltwater fish tanks

Yes, but it will need to be remineralized.

Can goldfish live in distilled water?

Goldfish require mineralized water, therefore distilled water alone would not be good enough. You would have to remineralize the water.


1. Publications, IWA. “Distillation Treatment And Removal Of Contaminants From Drinking Water | IWA Publishing”. Iwapublishing.Com, 2020, Accessed 18 Jan 2020.

2. “Purified Water”. En.Wikipedia.Org, 2020, Accessed 19 Jan 2020.

3. “Mineral Water”. En.Wikipedia.Org, 2020, Accessed 19 Jan 2020.

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