Is Rain Water Good for Guppies?

No, rainwater isn’t good for guppies. The reason for people being concerned about this aspect is linked to keeping guppies in outdoor ponds. What happens if it rains a lot? Will this affect your guppies in any meaningful way?

Yes and no, depending on the context. Let’s dive into the issue more in-depth.

Can Guppies Live in Rain Water?

No, absolutely not. Rainwater comes with several problems, such as:

– Dangerous Chemical Content

Rainwater is basically formed in the clouds and occurs when clouds of different temperatures meet and create condensation. The problem is that clouds tend to accumulate a lot of atmospheric chemicals, often leading to acidic rains. These can hurt your fish even in small quantities.

The problem is made considerably worse by the fact that you never know which type of chemicals are present in the water. Or in which quantities. So, keeping your guppies in rain water-only is a gamble you can’t afford to be playing.

– Dangerous Bacteria Buildup

There are a variety of viral pathogens that thrive in rainwater and pose great risks to your guppies’ health. These microorganisms multiply fast if environmental conditions are adequate, especially with your fish facilitating their spread. This happens because it’s extremely challenging to control the quality of rainwater, especially in an outdoor pond.

You could sterilize rainwater to use it for your indoor tank. The problem is that the process requires eliminating the bacteria and parasites and removing dangerous chemicals. The entire sterilization process will take time and resources, at which point it is not even worth it anymore.

– Disrupting the pH Levels

The rain water’s chemical content will affect your guppies’ water pH. Most rainwater contains sulfuric acid in various amounts, along with a lot of other harmful substances. Whether the rainwater will increase or decrease the pH level depends on where you live and the chemicals present in the water.

For instance, much of the rainwater in the US is acidic. This is a natural outcome of environmental pollution near large cities. As a result, rainwater will decrease the pond water’s pH, making it more acidic. This effect can grow significantly, depending on the water’s chemical content.

If rainwater is rather clear, it will dilute your pond water, increasing the pH. Which, depending on how much the pH fluctuates, can come with a different set of risks.

The changes in the water’s pH rank as the number one killer among pond guppies.

All these issues show that rainwater isn’t fit for guppies. You should never rely on rainwater alone when creating your guppies setting. There are other, safer options which we will discuss shortly.

So, can you keep guppies in an outdoor pond, knowing all these problems? Yes, so long as you test their water regularly and assess the quality of rainwater before moving your guppies in the pond. This will tell you whether your guppies can live in the pond or they risk chemical poisoning.

Can Guppies Survive in Rain Water?

It’s very doubtful that your guppies will survive in rainwater only, primarily for the reasons I’ve already mentioned. Rainwater isn’t safe for them due to their chemical content, low minerals, and creating the perfect breeding ground for various dangerous pathogens.

That being said, you can accommodate guppies in an outdoor pond, provided you monitor the water’s pH and chemical content regularly. You should also get a heater to control water temperature since rainwater is colder and can cause temperature fluctuations. Other than that, you shouldn’t use rainwater for your tank guppies.

There are more reliable options to go for, which we will discuss in the following section.

What Type of Water is Best for Guppies?

There are several types of water you can use for your guppies. Just remember that each type most likely needs treating before use for reasons we’re about to discuss. The best water options include:

  • Tap water – Affordable and readily available, but not as safe as you think. Tap water contains chlorine and various chloramine compounds, which are poison to your guppies. You always need to dechlorinate the water before using it for your fish. I recommend doing so with the help of a dechlorinating solution. Most dechlorinating solutions also function as conditioners and mineralize the water to create a safer environment for your fish.
  • Well water – The good thing about well water is that it doesn’t contain chlorine or other chloramine compounds. However, this means that well water is not regulated, so it’s most likely contaminated with a variety of chemicals and pathogens. These may not affect humans but can affect fish. Only use well water after you’ve performed chemical and biological decontamination. Use activated carbon to decontaminate the water and remove dangerous chemicals and aerate it to increase the oxygen levels. Also, get a tester kit to make sure the well water is safe to use.
  • Distilled water – A great option due to lacking any contaminants, but a poor one due to the complete absence of essential minerals. Distilled water is pretty much sterilized to remove all pathogens and contaminants that could jeopardize your fish’s lives. However, you should re-mineralize it before using it for your guppies.
  • RO/DI water – Deionized and Reverse Osmosis water types are also sterilized liquids, clean of all chemical compounds and harmful pathogens. As with DI water, you need to add a conditioner to the environment to re-mineralize the water and make them safe for guppies.

Rainwater doesn’t really fit anywhere in this context. It’s too volatile, metaphorically speaking. You need to put on a lot of effort to turn rainwater safe for your guppies. The efforts are not worth it, seeing how there are better alternatives you can fall back on.


If your guppies live in an indoor setting, there’s no reason to use rainwater. You have better and safer options available.

If guppies live in an outdoor pond, I recommend protecting their environment against rainwater. Maybe install a temporary cover to use for rainy days or place the pond in a covered area, safe from rainwater and direct sunlight.

avatar Noah
I’m Noah, chief editor at VIVO Pets and the proud owner of a playful, energetic husky (Max). I’ve been a volunteer at Rex Animal Rescue for over 2 years. I love learning and writing about different animals that can be kept as pets. read more...

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