How to Make Tap Water Safe for Fish?

Most fish keepers use tap water for their aquarium, which is absolutely normal. Doing regular water changes is essential for a healthy aquarium.

When I was beginner, I always hated changing water in my aquariums. Not because it is a laborious task, but because every time I did change the water, few my fish died.

I was sad, so I skipped water changes, but then my fish got sick because of the dirty water.

How to Make Tap Water Safe for Fish?

This page may contain affiliate links, which will earn us a commission. As an Amazon Associate we earn from qualifying purchases.

How to Make Tap Water Safe for Fish?

I had no idea why my fish die, until someone told me that tap water is harmful for fish.

Ok! But if tap water is harmful, why everyone is using tap water for their aquariums? Well, although tap water is harmful to use it in an aquarium, you can make it safe for fish.

In the following, I will tell you why tap water can be harmful for your fish and will give you a few tips on how to make it safe.

Why Tap Water is Harmful to Fish?

Before going into the methods of making tap water suitable for fish to live in, you need to understand why exactly tap water is harmful to them.

First and foremost, you need to understand that before the water reaches your tap, it is treated to prevent you or any other user from contracting diseases. One of the most common chemicals used to treat water is chlorine.

Chlorine kills all the bacteria in the water that is why it can prevent you from contracting diseases. In as much as this is beneficial to human beings, it is detrimental to fish.

The fact that chlorine eliminates all bacteria means even the healthy bacteria cannot survive. So when the healthy bacteria in the water is killed it causes an ammonia spike. Ammonia is a toxic substance to fish and could be lethal if proper care is not put in place.

In some places, people add potassium hydroxide to water so that it does not corrode the pipes. When potassium hydroxide is added to the water, it raises its pH level.

When you take that water, put it in an aquarium, and then place your fish there, there are high chances that it may die. Because fish are not tolerant/can not survive in water that has high pH levels.

How to Make Tap Water Safe for Aquariums?

So, if you are using tap water for your aquariums, as many people do, here are some good methods to make it safe for your fish and plants.

1. Use water Conditioner / Dechlorinator

Using a water conditioner is an excellent way of getting rid of chlorine in water and thereby making it safe for use in a fish tank. A water conditioner is also known as a dechlorinator.

There are various ways of dechlorinating water, and they include:

  • Installing an aerating sprayer – One of the means of dechlorinating water for fish is by using a sprayer, which adds air into the water as it enters into the fish tank. The process works by taking into account one critical feature of chlorine, it is volatile, and it usually dissipates in water by itself. The aeration sprayer speeds up the process, and after the process is complete, you will get water safe for your fish to stay.
  • Using a Dechlorination Agent – One of the most effective ways of eliminating chlorine is by adding a dechlorinating agent to the water. If you are planning to use a conditioner, you can consider going for the Seachem Prime conditioner. Prime not only removes chlorine from water permanently but also detoxifies it by eliminating ammonia, nitrate, and heavy metals.
  • Use an air pump – before adding tap water into your tank; you can eliminate the chlorine by using an air pump. The air pump does this by aerating the water. Make sure you buy the right pump for your tank according to its size and type.

2. Let the Water Sit For a Day

Another excellent way of getting rid of chlorine in the water before placing your fish in it is by off-gassing.

Off-gassing is a process of chorine elimination that involves placing the water in an open bowl and let it sit there undisturbed.

The chlorine present in the water will escape into the environment naturally. Typically, the process takes 24 hours, and after that, you can use the water in your tank.

3. Boil and Cool the Water

If you are looking for an effective, safe, and less costly method of making water safe for your fish, then boiling is your answer.

When you boil water, aeration takes place, and when the aeration process mixes up with the heat, chlorine is eliminated with ease.

It is also important to note that boiling also removes chloramine, a chemical similar to chlorine, but has a longer-lasting effect on water.

Take a clean pot, place the water in a pot, light a fire and place the pot on the fire for about 20 minutes. Once the boiling process is over (after 20 minutes), remove the pot.

Always remember to let the water cool before pouring it into the fish tank.

4. Use an RO/DI System

Reverse Osmosis (RO) is a method of purifying water that involves removing the H2O water molecules to a separate holding tank. When this happens, all impurities are left behind, usually in a Reverse Osmosis filter.

Deionization (DI), on the other hand, involves eliminating all charged particles. In this case, you are required to use a Deionization filter. In both, water is cleaned at a molecular level by separating impurities and the water using a filter.

In case you choose to follow this process, make sure you choose a good filter. You can start by looking for the AquaFX Barracuda RO/DI Filter.

The 4 stage filter comes with a 2-micron chlorine guzzler carbon block filter.  It also comes with a pressure gauge that allows users of unsafe ranges. The AquaFX filter also features a TFC membrane that has high flow and high rejection capabilities.


The water in which your fish lives/stays in is a delicate thing as it plays a vital role in determining whether or not the fish survive.

With that being said, a fish owner should ensure that he/she does everything possible to ensure that you put your fish in the “proper” water.

Since tap water is the most available, there are many ways of ensuring that it is safe for the fish. You can start by using an RO/DI system, which cleans water at the molecular level.

Using a de-chlorinator is also an excellent method of making water safe for fish. Let us not forget that you can also boil the water to eliminate chlorine and then cool it to use in the aquarium or fish tank.

Leave a Comment

Your email address will not be published. Required fields are marked *