Can You Put Bottled Water In A Fish Tank? 5 Reasons You Shouldn’t!

Feb 1, 2022

Can You Put Bottled Water In A Fish Tank

Water is to fish what air is to us. So, I don’t think I need to stress the importance of clean and safe water for fish. However, there’s not just one kind of water available to use in fish tanks. Instead, there are dozens of them broadly categorized into three types: utility grade, working grade, and drinking grade. 

So, what category does bottled water fall in? Obviously, the third – drinking grade! But is what is safe for us safe for our fish as well? Can you put bottled water in a fish tank?

Let’s find out. 

Can You Put Bottled Water In A Fish Tank?

Bottled water isn’t downright fatal for fish, but you should steer clear of it. Bottled water is either purified water, filtered water, or spring water. Therefore, it may have gone through filters that get rid of some of its beneficial components. On the flip side, it may have some extra minerals that aren’t deemed healthy for fish. 

Economically too, it isn’t really viable to use bottled water in our tanks, is it?

A bottle of water costs around $1.45 on average in the US. And if you have a big tank, you’d need to purchase several bottles of water to fill up your tank. 

As a result, the upkeep of your fish tank becomes a lot more costly.

So, while bottled water may be a good investment for your health, it’s not really desirable for fish tanks. 

Let me make it a bit more clear. 

You see, there are basically three types of bottled drinking water available to us right now. They are:

Spring Water: It’s water that’s collected from the underground. It may or may not have gone through an additional filtering process. 

Filtered Water: It’s tap water that’s gone through several filters like charcoal to enhance the taste. 

Purified Water: It’s tap water that undergoes an RO/Di system or is distilled. 

And the thing is, each of these water variants comes with different parameters. Thus, you’d need to test your bottled water meticulously before deciding how to adjust it to the fish’s preference. 

On top of that, most bottled waters available in the market still contain a good concentration of chlorine. And you probably know why chlorine is harmful to fish. 

Below, I’ll lay down a few reasons why bottled water is not suitable for aquariums. 

5 Reasons You Shouldn’t Use Bottled Water In Aquariums 

Bottled water often doesn’t have the minerals required for pH buffering. And that’s because the water is either distilled or treated with reverse osmosis (RO). The lack of minerals and the subsequent lack of pH buffering will lead to instability in the tank, proving fatal for fish. 

Bottled water is mainly treated with chlorine to eliminate harmful germs and bacteria. And while chlorinated water is good for us, it’s highly toxic for fish and crustaceans alike. 

Bottled water is often purely distilled. And this kind of water can cause the salt present in the fish’s body to diffuse through osmosis, leading to neurological problems and even proving fatal. 

Bottled spring water varies in composition in terms of pH and mineral content. It can thus mess up your tank’s pH and hardness – ultimately making the water unsuitable for fish. 

You will have to most likely remineralize the bottled water, which isn’t just a painstaking process but also a costly one. Therefore, we can safely assume that bottled water is not an affordable choice for the hobby. 

What Kind Of Water Is Best For Fish Tanks?

Different kinds of water have different mineral compositions. And while you can pull a few tricks to alter the water’s pH and hardness, manipulating the mineral composition can be tricky.

Therefore, before answering this question, let’s look at what minerals fish need.

The key minerals most fish species need in bulk are calcium and phosphorus. 

Calcium is pretty easily found in hard water and is absorbed by the fish through its gills. On the other hand, most aquatic plants lend sufficient phosphorus that fish need. 

Besides these two, fish also need minute amounts of magnesium, sodium, iodine, iron, zinc, copper, potassium, and sulfur. 

Now that we know what minerals fish need, I scoured through different sites and compared mineral composition for different kinds of water. 

And from my research, what I found is that tap water is still the best and most economically viable water option for fish tanks.

According to USDA, calcium, phosphorus, magnesium, iron, copper, sodium, zinc, and manganese were found in the nationally representative drinking water samples. 

However, as you probably already know, you must condition tap water first to get rid of chlorine and other potentially harmful compounds.

Recommended Readings!

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How To Use A Water Conditioner In The Fish Tank?

There are basically 2 ways of adding water conditioner into the water. They are:

  • Adding water conditioner by using a container 
  • Adding water conditioner by using a hose 

Using A Container 

In a small container, add some water and conditioner as instructed in the package. Swirl the mixture with a clean stick or spoon and pour it into the tank. 

Using A Hose 

If you perform water changes using a hose, you can easily add conditioner as new water to the tank. Once you measure the amount of conditioner, slowly drip it into the water as it enters the tank. 

You can safely use a water conditioner even with fish present in the tank. These compounds are scientifically formulated to be used even in the presence of fish.

If you add the conditioner incorrectly or in the wrong amounts, it can bind oxygen and possibly become fatal for fish. Read more about it here. 

Read: Can Too Much Water Conditioner Kill Fish?

Here’s a link to our favorite conditioner from Seachem:

What Does It Do?

  • Eliminates chlorine 
  • Buffers pH 
  • Detoxifies heavy metals 
  • Neutralizes ammonia 
  • Protects fish’s slime coat 
  • Eliminates copper 

How To Add Minerals Back To The Water?

If you’re not a fan of tap water and insist on using distilled water, you need to remineralize it first. And remember, remineralization is essential for reverse osmosis and deionized water as well. 

To add the minerals back into the freshwater tank, you can add a bit of tap water to the tank. But the wise choice here would be to buy a remineralizer available easily and add several drops to the water as directed. 

For saltwater tanks, the salt mix you need to use usually leaches minerals into the water. 

And here’s a link to our favorite mineralizer – once again by Seachem. 

What Does It Do?

  • Restores and maintains water’s GH
  • Replenishes vital minerals erased during RO
  • Prevents osmotic shocks and stress 

Frequently Asked Questions

Before we end the article, here are some of the most frequently asked questions. 

Can You Use Spring Water In Fish Tanks?

Spring water varies in composition from region to region. The mineral content and pH level can change drastically, creating an unstable environment. Spring water is also often chlorinated.

Hence, it’s not really a good idea to use spring water in fish tanks.

Can You Use Purified Water For Fish Tanks?

Purified water is water that’s been mechanically processed or filtered to eliminate bacteria, viruses, and harmful minerals like copper and lead. But unfortunately, beneficial minerals like calcium and phosphorus are removed too. 

Thus, it doesn’t have enough mineral content required to buffer pH. And if you use purified water exclusively in the tank, it’ll create an unstable pH environment, which is harmful to the fish. 

Can You Use Well Water For Fish Tanks?

Unlike tap water, well water doesn’t contain traces of chlorine. However, using well water can lead to several other issues in the tank. 

Well water isn’t regulated. Thus, depending on your region, we don’t really know if well water contains high concentrations of other contaminants. 

For example, if you live near an industrial area, the well water may contain volatile organic compounds (VOCs) – such as the chemicals present in pesticides, herbicides, and paints. 

Likewise, if you live near an agricultural area, coliform bacteria and nitrates stemming from fertilizer can contaminate the well water. 

And that’s not all. Well water can also differ in hardness and pH and require extra aeration due to low oxygen content. 

Frankly, treating well water to be used in a fish tank is a hassle. 

Final Words: Can You Put Bottled Water In A Fish Tank?

To put it simply, it’s not really recommended to add bottled water in fish tanks. There are one too many caveats that attached to it

For instance, it can make the water parameters unstable, can contain traces of chlorine, lack minerals, and can be pretty heavy on your pocket!

Recommended Readings!

Can Too Much Water Conditioner Kill Fish? It Can Bind Oxygen!

Black Mold In Fish Tank | Effective 4-Step Treatment

How To Save A Dying Cichlid? 4-Step Guide

What Does Blue Light In Fish Tank Do? What About Red And Green?

rohit gurung author at urbanfishkeeping

About Rohit Gurung

My never-ending love and fascination with Aquascaping started when I received a red-eared turtle for my 10th birthday.

Apart from researching and writing, I spend hours gazing at my 3 turtles. And yeah, I bask alongside them too.