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Can Rain Barrel Water Go Bad?

Can Rain Barrel Water Go Bad?

Being an avid gardener, my wife loves to water her flowers using the rain we collect in our patio’s rain barrel.

However, we found out the hard way that if you don’t take proper precautions, your rain barrel can fall victim to all sorts of undesired conditions. One moment we were using the cloud’s bounty to grow our plants.

The next, we had an insect-infested reservoir that smelled like rotten eggs. To answer the question, rain barrel water can go bad.

Psst

We wrote an entire rain barrel buying guide for 2020. If you’re in the market, consider giving it a read!

What Happens?

First, I should note that the water itself doesn’t actually expire like milk would expire.

However, your rain barrel isn’t a closed system. Bacteria, insects, algae, and other contaminants can breach the outer perimeter of the barrel and set up shop inside. This normally isn’t a problem — bacteria is literally everywhere and a small amount of insect/algae contamination won’t be enough to hurt your plants.

The problem occurs when the water remains stagnant and unused for many weeks (the same problem happens in birdbaths).

Sitting water is a breeding ground for foul-smelling bacteria, mold, parasites, and unwanted insects (like mosquitoes). While these things are unlikely to hurt your plants, they’re unwelcome and can cause major problems/illnesses for pets, small children, and even adults.

How To Prevent Rain Water From Going Bad

You have a few options to prevent your rain barrel water from going bad. Each has its pros and cons, but one, in particular, is preferred. First, let’s cover the preferred approach.

Regularly Cycling Water

Do you remember the expression “a rolling stone gathers no moss?” Well, the same truth can be applied to rain barrel water. Since the problems only start to surface when the rainwater is stagnant, you can easily avoid the problems by making sure the water keeps moving. To do this, simply remember to use your rain barrel often while draining it if the water ever sits for too long.

Bleach / Chlorine

If you already have contamination in your rain barrel, a small amount of bleach or chlorine will kill the parasites and bacteria. As long as you use the proper amount, it shouldn’t bring any additional danger to pets or people. What’s the proper amount of bleach to sanitize a rain barrel?

The CDC‘s rule of thumb is 1/8 tsp – 1/4 tsp of bleach per gallon of water. You’ll want to adjust the amount depending on the size of your rain barrel and the level of contamination. To save you a bit of arithmetic, I’ve compiled this handy table.

# of GallonsAmount of Bleach
502 – 4 tablespoons
1004 – 8 tablespoons
2001/2 cup – 1 cup

To know whether you should use the first number or the second number, you should evaluate the water quality. If it’s cloudy or discolored, I’d suggest using the second number. If it’s otherwise clear, you can probably use closer to the first number.

For chlorine, the calculations change 4mg per liter. To figure up how much we’ll need to use, we first have to convert it to imperial units. Again, here’s a handy chart to help things along.

# of Gallons# of LitersAmount of Chlorine
50~190760mg
100~3801520mg
200~7573040mg

Why Does My Rain Barrel Smell Like Rotten Eggs?

Folks are generally confused when their rain barrel starts smelling like rotten eggs. If the water is coming from the sky, how can it be imbued with the smell of sulfur?

Most often, your rain barrel smells like rotten eggs due to decaying plant particles brought down off your roof, through your gutter, and into your barrel. If you don’t have a filter going into your rain barrel, those particles can get inside. As the bacteria consume these organic compounds, the sulfuric smell of rotten eggs is produced.

If your rainwater barrel smells like rotten eggs, it’s a really good sign that you should either add some bleach or clean out the water and sanitize. However, if you’re reasonably sure that your rain barrel water is still safe, you can simply choose to mask the smell.

How To Keep Rain Barrel Water From Smelling

We wrote a complete guide on how to keep rain barrel water from smelling at this link. But if you’re in a hurry, or don’t want a complete solution, read on.

There are a few things you can try in order to keep rain barrel water from smelling bad. My favorite idea is to put live mint plants inside the barrel and wait for nature to do its magic. Mint plants will generally take root in anything, so they’re a great candidate for covering up a stinky rain barrel.

If you don’t have a mint plant handy (or if you simply lack a green thumb), you can add some baking soda to the barrel each time you drain it. Baking soda is another natural odor eliminator and can do wonders for your rain barrel.

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How to Keep Your Rain Barrel From Stinking – Captain Patio

Tuesday 19th of April 2022

[…] is happening to you, it means that you are not using the water fast enough. Be sure that you are cleaning the barrel regularly and not letting the water sit for too […]

Jim Nadlonek

Friday 27th of August 2021

I use my rain barrel water for the plants around the yard. Is this chlorine level suitable for plants?

Thomas Kramer

Thursday 20th of May 2021

Hi Chuck, Thanks for the information. In my case I have a 2 plastic 50 gallon barrels. Both have become infested with algae which I didn't consider a real problem but then I added bleach, no doubt more than the recommended amount. Now there is a tan colored scum on the surface and a definite sewer type smell. I guess I killed all the algae and what's left is bacteria. Do you have any thought or suggestions? I live near Casa Grande, AZ between Tucson and Phoenix. Thanks for reading.

Henry Beach

Wednesday 12th of May 2021

Will chlorine tablets that I use in my pool work for keeping parasites' out of my rain catch barrel.

I only grow tomato plants in a 5 gallon buckets, and I have found that rain water makes for great growing, and my city water seems to stunt their growth.

This is the 1st year that I started collecting rain water, and I don't won't to make my rain water to be the same as my outdoor water spigot that is high in chlorine.

M. Christina Borges-Lutz

Saturday 8th of May 2021

Thanks for all tips, I have one more question: my rain barrel is smelly, and has algae! Now I know how to handle that, but before doing all this, do I have to empty the barrel?

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