What is really in that rain water?

cribscreek(z7/8 NC)August 17, 2005

I was told recently that the reason that city water doesn't seem to sustain plants as well as rain water is because of the presence of hydrogen peroxide in rain water. I have never heard this before and wondered if it's legit. Does anyone know of any additive to put in the water, such as in the hose feeder, that would make the water more suitable? During such hot weather, it seems that no matter how much I water, the plants are longing for something else...... and I already luv em ok.

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chapelhillgardener(7a NC OrangeCo)

when i was young, and *knew everything*, i thought my mother was crazy when she'd say hose water is a poor substitute for rain. now that i'm middle-aged and "crazy", i'm reminded with every rain how right she was.

    Bookmark   August 18, 2005 at 8:56AM
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I think whoever told you that is confused.

Rain water is generally better for your plants than public water. If you are in an area of regular pollution alerts, rain might pick up some nitrates, sulfates, etc. from the air and become "acid rain", but that isn't generally a short term problem.

Public water, having been treated with chlorine or other chemicals, is a problem for already heat stressed plants. Imagine spraying a very weak bleach solution on them---which is exactly what you are doing. In the heat of summer when rains are infrequent, and bacteria in the water is plentiful water treatment plants may need to add to even more chemicals to prevent water born illnesses.

As for peroxide---I doubt it. It is sold in brown plastic bottles, because it breaks down into water very quickly on being exposed to sunlight.

    Bookmark   August 18, 2005 at 9:14AM
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chapelhillgardener(7a NC OrangeCo)

i don't think there's any confusion about the premise that rain is better than city water.

    Bookmark   August 18, 2005 at 9:44AM
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But there is a problem if you plan on collecting rainwater that runs off your roof. Most roofs have asphalt shingles and most of them leach some pretty harsh chemicals when it rains. There are a few plants out there that can't handle common tap water chemicals like flouride or chlorine even in trace amounts.

    Bookmark   August 18, 2005 at 10:31AM
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I have rain barrels that collect rain off the roof and I haven't had a problem. My roof is very steep, so the only thing I occasionally get is some grains from the shingles, which don't seem to add enough to the water to do anything to the plants.

    Bookmark   August 18, 2005 at 11:14AM
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What has really fascinated me over the years is rain lillies (zephyranthes). You can water and water them and you will get no blooms - get a good rain and they just come alive with blossoms. I never did understand that until I took the Master Gardening course and we discussed it and determined that there are just natural nutrients in rain water that spur the blooms - in other words - "all watering is not equal"

    Bookmark   August 18, 2005 at 11:44AM
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cribscreek(z7/8 NC)

It does seem like someone, a chemist maybe, would come up with something we could hook up to our miracle grow feeder and put those nutrients back into the water. Hmmmmmmm. Oh, i forget, im not a chemist lol.

    Bookmark   August 18, 2005 at 12:36PM
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I remember DH told me he read somewhere that there is nitrogen in rain water -- perhaps that's the difference.

    Bookmark   August 18, 2005 at 12:39PM
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The local gardening hot-shot also told me about Zephyranthes not being fooled by hose watering so I never tried to encourage them to bloom. Then just a few months ago Carl Schoenfeld of Yucca-Do Nursery gave a lecture at the Raulston Arboretum showing slides of his plant collecting trips into Mexico and of his wonderful collection of species and hybrid Rain Lilies. He said that if you really soak them you CAN fool them - that is the amount of soaking not the quality of the water. I went home and drenched a pot of mine and they did bloom. Mr Schoenfeld is like the god of rainlilies.

    Bookmark   August 18, 2005 at 1:55PM
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I always thought there was an extra kick of nitrogen in rain water too! Not only must the chlorine stress plants, but I'm sure flouride isn't too swell for them either. I have a hunch this is why so many houseplants get sick and croak. I now make a point of running outside with my Boston ferns every time it's raining. I even have my kids trained now to set them out if I'm not home and they're doing spendidly for the first time in my life!

    Bookmark   August 18, 2005 at 2:01PM
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janandalan(Z7-NC Piedmont)

Yes, rainwater contains hydrogen peroxide. It's a result of water falling through the ozone found in the atmosphere. Rainwater does indeed benefit plants more than standard tap water. See linked article.

Here is a link that might be useful: hydrogen peroxide in rainwater

    Bookmark   August 18, 2005 at 3:55PM
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cribscreek(z7/8 NC)

Thank you, Thank you, Thank you Janandalan

Now if any of you wizs out there can figure out at what ratio to use it in the Miracle Grow feeder, we are in business!!


    Bookmark   August 18, 2005 at 5:19PM
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cribscreek(z7/8 NC)

Here is a pasted in portion of that article referred to above. Very Interesting.

Helps Plants
It is this hydrogen peroxide in rainwater that makes it so much more effective than tap water when given to plants. With the increased levels of atmospheric pollution, however, greater amounts of H202 react with air-borne toxins and never reach the ground. To compensate for this, many farmers have been increasing crop yields by spraying them with diluted hydrogen peroxide (5 to 16 ounces of 35% mixed with 20 gallons of water per acre). You can achieve the same beneficial effect with your house plants by adding 1 ounce of 3% hydrogen peroxide (or 16 drops of 35% solution) to every quart of water you give your plants. (It can also be made into an excellent safe insecticide. Simply spray your plants with 8 ounces of 3% peroxide mixed with 8 ounces of white sugar and one gallon of water.)

    Bookmark   August 19, 2005 at 1:46PM
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That's interesting. Now I hope we get a little rain in the next few days, with temps up to scorch again this weekend!

    Bookmark   August 19, 2005 at 2:08PM
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cribscreek(z7/8 NC)

Alicia, I can't help but think that its worth a try to see if it will make my plants do better during dry and hot spells here. I'm going to experiment with it and see what happens, if nothing else, I will learn something I didn't know before lol.

    Bookmark   August 20, 2005 at 1:14AM
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I think you need to understand the purpose of that linked article above before you read any "benefit for plants" into it. It is trying to convince you that peroxide is natural and safe enough that humans should ingest it.

The benefit of rain water on plants is that it has less chlorine and fluorine than tap water....and a few trace nutrients as a result of pollution. There might be some miniscule amounts of peroxide, but peroxide is extremely unstable especially in sunlight and breaks down into water.

If I had a sick plant with an external bacteria or mold problem, I might try spraying with a 1/3 solution of peroxide.
...but to spray dry but healthy plants in hope of improving them is likely to stress them even more. Peroxide is not a plant nutrient. It is an oxidizing agent the same as chlorine....and plants don't live on oxygen.

Maybe the idea that it is good for plants came from the fact that EPA has approved its use in pesticides....when really the idea is that it doesn't do much harm to plants..or people..see link below.

Someone cautioned about using rain water from roof runoff. Some new roofs use a zinc strip to retard mildew growth on shingles. I think it is the zinc that leaches into the water that can be a problem-----otherwise you can use it.

Here is a link that might be useful: peroxide and plants

    Bookmark   August 20, 2005 at 1:42PM
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cribscreek(z7/8 NC)

Interesting Perineal, but at the same time, since there is obviously something in that rainwater that makes the plants do better, it might just be a start to a common easy solution to add to water that will solve the problem. I think Nitrogen would probably influence it also. Maybe many components. I've heard that you can get mineral dust at a local rock quarry, and maybe adding some of that to the water might help. I would also like to know if there is any additive (other than sunshine) that would knock out the chlorine and floride.

    Bookmark   August 20, 2005 at 2:39PM
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Peroxide is singlet Oxygen and water. should be called hydrogen dioxide (red tape gets in the way of this due to the commercial side of science wanting to keep people in the dark ages and exploit them medically with petrochemical derivatives , otherwise called pharmaceuticals). aerobic (viruses aren't aerobic) living things need oxygen as a disinfectant. It is good for you too, not just your plants. dilute to about 0.5% (Safe bet) for you plants. I bath in it (500ml of 12% per bath). and drink it(up to 60 drops of 12% in a glass of water, three times a day. start at 12 drops and work your way up day by day). and put it (0.2%) in my ears to instantly stop approaching flu (it fizzes lots, but don't be scared, it's safe and clears you sinuses). One can even take it intravenously (0.15% H2O2, 5% dextrose (keep your sugar levels up), 2mg magnesium chloride (stops you veins from healing\scabbing) in 250ml water. Once a week, for 4 weeks) for cancer therapy. The only downside is it's cheaper than chemo. Much cheaper. Unfathomably so.
We don't breathe enough nowadays, plus there is a lot less to breathe (In terms of Oxygen). Every time anything burns, or breathes (animals, not plants though), there is immediately less O2 around (As it forms compounds with the burning substances). Plants reverse this process, as we all know. This is why cities have little oxygen. Think of the damage we've done to our own environment in the past 100 years in terms of O2 depletion.. Yes, rain contains peroxide. It is the worlds cheapest and most potent disinfectant, Our bodies have been using it since bacteria (Not viruses!) started breathing.. H2O2 promotes the resession of cancer. cancer doesn't like breathing, as this kills it. It's most likely cause is a lack. look into anaerobic sugar-metabolism if you are curious. Your city plants will love highly diluted peroxide. Rainwater is the best, though. it contains lots, so instead of simulating it, use it. Just thought i'd say something on the topic of peroxide, as you doctor (dealer/runner) won't.
Ps. make sure you get food grade peroxide if you plan on ingesting it, as this way you can be sure it contains no potentially harmful stabilizers.

Here is a link that might be useful: One of many pages on the topic

    Bookmark   July 31, 2007 at 11:19AM
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hi all, what a great thread! I have been wondering this myself. I have one thought maybe you guys can clear up....dont you think that rainwater has (forgive me if I choose the wrong words) ions from the clouds like I heard are in the air at niagra falls and seem to make everyone there feel extra happy????


    Bookmark   July 31, 2007 at 8:51PM
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jqpublic(7b/8a Wake County NC)

Also for what its worth...when it rains it is cloudy and the temps drop to relatively comfortable readings for an extended period of time. Instead of the rain getting sucked in and evaporated right out it soaks in deeply and stays there longer??

    Bookmark   July 31, 2007 at 11:39PM
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aisgecko(7b Raleigh)

And (while this other stuff may be valid, I wouldn't know) when it rains you get complete coverage. So half an hour of rain is a good soaking, whereas an hour under a rotary sprinkler is barely enough.

    Bookmark   August 2, 2007 at 8:25AM
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dottie_in_charlotte(z7-8 NC)

Wondering if stored rain water loses any of its chemistry in storage?

    Bookmark   August 2, 2007 at 10:43AM
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Probably, Dottie - doesn't everything deteriote w/age (me included!)? And then there's always the debate over outgassing from plastic containers - like rain barrels - and yada, yada, yada ....

Sometimes ya' just gotta' pick your battles, do your best and rise above all the scientific studies. Mother Nature had things well under control before we humanoids started messing up the planet. I just try to do the best I can, as do all the rest of the GWC folks !

    Bookmark   August 2, 2007 at 11:07AM
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I have heard of people adding hydrogen peroxide to stored rain water, but I don't do it -- the plants seem fine...

    Bookmark   August 2, 2007 at 12:50PM
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What about well water? Since it is not treated with any chemicals, is it the same as rain water?

    Bookmark   August 4, 2007 at 10:45PM
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I have well water. Doesn't seem to do the same thing as a good rain no matter how much I water. Adele

    Bookmark   August 4, 2007 at 10:53PM
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Tammy Kennedy

ditto- we have well water, and rain is sooo much better. even a skimpy rain seems to do more than a good soaking with a hose.

so, what about rain barrels? because if it really is the whole hydogen peroxide thing, it would evaporate, right? so the rain barrels shouldn't do as well, either, in that case, but if it's because of micronutrients, than i'd think it would. perhaps it's a combo of everything together- maybe like so many things the whole is greater than a simple sum of the parts (temp, micronutrients, h2o2,lack of chems etc, ).

    Bookmark   August 5, 2007 at 12:06AM
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dottie_in_charlotte(z7-8 NC)

The farmers I've known have said that regular rain isn't as good as rain from a thunderstorm. Something about the ozone from the lightning.

    Bookmark   August 5, 2007 at 12:11PM
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jrcan(z8 Charlotte, NC)

Don't forget about pH. City water typically has a pH of 9 or 10 to prevent bacteria as well as rust in older pipes in the system. You can test your tap water for pH useing a simple fish tank tester. Our water in Rock Hill is a solid 10, when we lived in S. Charlotte is was 9. Remember, pH has a direct effect on nutrient intake and over time watering your plants with a high pH water will effect the pH of the soil..

I grow citrus trees in containers and they like a low pH level so I have determined through testing that 9 drops of sulfuric acid added to a gallon of water brings it down to around 5.8 to 6. I have done this for years and my citrus trees have done great. You can buy the sulfuric acid also at the pet stores, it is called pH down and is used to lower the pH in fish tanks.


    Bookmark   August 8, 2007 at 1:35PM
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I made two 55 gallon rain barrels and hooked them up to my downspouts. One on each side of the house. With our first rain they were both almost 3/4 full. But I noticed my water is brown. Is this normal? I do have asphalt shingles. Not sure if I should be using the water for the plants. Any advice or suggestions?

    Bookmark   June 28, 2008 at 10:57AM
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What is the smell when it rains?
Does watering with hose smell the same as the smell when it rains?
I have read that rain makes the air have more negative ions which may be good for us and maybe for plants.
If the air smell different when rain than when hose watering, why?

    Bookmark   June 29, 2008 at 9:29PM
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We have a turtle and his water has to be checked for PH at least once a week. Oddly enough our county water always tests as neutral.

All kinds of neat things happen during a rain that cause a variety of smells. Chemical reactions occur, the soil "opens up" and releases a variety of things including bacteria and minerals, the ph of the rain causes plants to release chemicals, the rain reacts with some of the chemicals from plants and other chemicals on the ground, bugs let off odors, and other interesting things occur. The humid air is an aroma enhancer and carries those scents through the air better and.... the humid air tends to open up your sinuses.

My hose water always smells like... the inside of a hose. ;)

    Bookmark   June 30, 2008 at 4:24AM
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One would think that well water would be "cleaner" than rain water OR house tap water, since it is essentially filtered through tons of dirt which removes any sort of chemicals or impurities. Long gone are the days when you could visit your local cold water creek and actually drink the water right out of it. I used to do that when I lived in MA. as a kid we would visit the local brook and go trout fishing, and could drink the water right out of it when you were thirsty, good and cold. That same brook is now polluted from run off of surrounding new community streets, as well as the main road, and from it's tributaries. The fish are far and few between I am told now.

Quite sad really, that area used to be loaded with lady slippers.


    Bookmark   June 30, 2008 at 11:54AM
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Clouds are pure water vapor - nothing else - formed by distillation of water up from earth. Water is H2O. Peroxide is H2O2, which can form and breakdown in small amounts within water, without anything added externally.

Rain can contain anything that rain falling downward can pick up from the air. Picking up environmental pollutants that lower pH is what causes "acid rain", for example. So chances are great that your rain has a quite different composition from your gandmother's rain. And it might not be good.

Rain off a rooftop will pick up "stuff" from the rooftop, but most of it should be pretty harmless and minimal, unless it's a brand new roof material, or an old degrading roof material.

I personally would not ingest hydrogen peroxide from the drugstore. It's not tested by the FDA, so there is no guarantee that minor, harmful contaminants are not present. Of course, that's true of vitamins as well, and I do ingest those.

There's a saying among environmental chemists that probably makes sense for this thread: Dilution is the Solution.

    Bookmark   June 30, 2008 at 1:21PM
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First, rain and clouds are not "pure water vapor". Rain and snow both may contain a variety of nutrients: phosphorus, sulfur, ammonium, nitrate, even metals like iron and manganese. Second, H202 (peroxide) cannot spontaneously form in 100% pure water, it requires a further oxidant (such as carbon dioxide).

Third, on an earlier post linking to an "article/opinion page" on hydrogen peroxide in rainwater; over 99% of gut microbes are anaerobes, not aerobes. Only in the lowest portion of the colon are their significant aerobes. The majority of these anaerobes are beneficial for nutrient uptake in the gut. Yes, anaerobes do cause intestinal issues--but you flush them all out you are also killing your ability to uptake nutrients and manufacture vitamins.

Fourth, it is correct that the smell of ozone is strong after a thunderstorm, contributing to that fresh smell. However, the strongest scent comes from geosmin, an oily compound produced by soil bacteria that is released after a rain. The human nose is very sensitive to this compound (able to detect the substance in concentrations as low as one part per trillion). That smell will be present whether watering with a hose or after a rain.

Stored rainwater will likely lose a proportion of nitrogen due to a growing microbial community that will convert any ammonium and nitrate to nitrogen gas, which will be lost to the atmosphere.

Rainwater and snow both contain significant numbers of bacteria (snow is nucleated largely by a plant pathogen). Estimates range from 1,000 to 1,000,000 bacteria per mL of water. These bacteria can be carried huge distances by wind and end up condensing with moisture into precipitation. Dust carried from China deposits bacteria into precipitation in the U.S., for example.

Frankly, I see no benefit of hydrogen peroxide on plants. If your intention is to kill the microbial community that co-exists beneficially with the plant roots, then douse the plants with H2O2. The reason it bubbles when you place it on a wound is due to a catalase enzyme in bacteria (and human cells as well) that decomposes the H2O2 to water and oxygen. So, you are not only killing bacteria, but also your own cells.

Just some thoughts

    Bookmark   April 2, 2009 at 12:07PM
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dottie_in_charlotte(z7-8 NC)

Thankyou,dobber. I love the science explanations.
I guess we can conclude that city water, especially in summer with its higher chlorine content, is only good for moistening the soil so your lawns stay alive.
We all probably should be investing in rain barrels.

A question to dobber..would adding surfectants to rain barrel stored water be useful? I do that sometimes when the ground is really dry to make the water absorb faster rather than running off.
"surfectants" being a few drops of detergent to 5 gal pail of water.

    Bookmark   April 2, 2009 at 12:29PM
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It has been raining hard today in the Triad. I got bored. I found this thread. I am glad it is raining! I know my windmill palms love it.

I hope my basement does not flood.

    Bookmark   December 21, 2011 at 9:29PM
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wertach zone 7-B SC

Thanks for finding this GreenfingerGene! Very interesting. I have a well and city water. I have noticed well water does better on my garden than the city water. But rain trumps them both, hands down!

I have a rain barrel on my tin roof barn and it does better than the water from my shingle roof house barrel. But still not as good as even a light sprinkle of rain!

    Bookmark   December 22, 2011 at 11:41AM
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Falling rain also is bombarded by the nitrogen and carbon dioxide molecules in our atmosphere (72% of the air we breathe is nitrogen).

The result is all rain that falls being ever-so-slightly acidic in pH and contains a basic "fertilizer":

As rain drops drop through the air, carbon dioxide is trapped and carbonic acid is formed (H2-CO3)

Lightning helps fuse nitrogen and oxygen atmosphere gases into nitric oxide (N-O) that quickly becomes a more stable nitrogen dioxide (N-O2) in the air. Nitrogen dioxide in the air is is trapped/absorbed by rain droplets and dissolves/degrades to simple hydrogen atoms (H) and nitrate (N-O3).

    Bookmark   January 25, 2012 at 7:14PM
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I am still inclined to think that there are chemicals in tap water that are not present in rain water and it makes tap water less beneficial than rain water, rather than the other way out. But what is more important, plants react to rain differently. Plants react to environmental signals. When they "know" it is raining, they react to air humidity, soil nutrient availability, what have you, and you see them grow and develop at an appropriate rate. A very prominent example of that is this lily species mentioned here, she reacts to the rain signal but not to a human with a watering can. When you water them, the signal is absent or at least present at a much lower level. Of course, it does not mean that we should stop watering. It is just that rain is really good for plants.

    Bookmark   January 29, 2012 at 1:56PM
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dottie_in_charlotte(z7-8 NC)

I'm on well water now.
Would it be safe to say that except for trace metals and some dissolved minerals, that well water is depleted in nitrogen and oxygen as it percolates through the soil?

Would a nitrogen additive and an aeration process in the rain barrel improve the water quality closer to rainwater?

    Bookmark   January 31, 2012 at 10:33AM
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