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View Full Version : Diluting shampoo - not such a good idea?



Lamb
June 4th, 2009, 08:10 PM
I just came across this and I'm wondering if it's true:


once you've diluted shampoo, you've rendered the preservatives in it too weak to do their job. Your watered-down shampoo is chock full of nitrogenous compounds and carbohydrates that bacteria and fungi will find oh so tasty. So if you let this solution sit for a day (or more) and then dump it on your hair, you'll also be dumping on a nice homemade culture of various nasties that may find your scalp to be equally delicious. You could find yourself getting a case of dermatitis (http://www.everything2.com/index.pl?node=dermatitis&lastnode_id=82014) or an infection.
http://www.sff.net/people/lucy-snyder/brain/2005/08/shampoo-ingredients.html

Can some chemist/scientist posters help me out here?

Speckla
June 4th, 2009, 08:12 PM
I guess I've been putting myself at risk for years. Doesn't shampoo already have water in it? What keeps that from growing too much bacteria? Isn't shampoo antibacterial like all soaps?

MandaMom2Three
June 4th, 2009, 08:16 PM
I never dilute shampoo until I'm about to use it anyway :shrug:

Flynn
June 4th, 2009, 08:18 PM
That doesn't sound quite right to me... though if you're really worried, just keep it in the fridge.

What's the use-by date on your shampoo? Does it even have one? It'd be heavily preservative-laden enough that it has a shelf life of years. I don't think dilution -- even heavy dilution -- could reasonably reduce that to a day or less.

As for soap and detergent being antibacterial, not... quite. Not like I think you're thinking. Surfactants break up bacterial/fungal colonies, and stop them from sticking to you, so you can just rinse the off. In and of itself, it isn't antibacterial like an antibiotic drug is. I mean, a cake of soap can still grow mold...

cakedcake
June 4th, 2009, 08:20 PM
I'm no chemistry pro, but that sounds pretty extreme to the daughter of a lady who diluted every shampoo with which she ever came into contact. We have not had dermatitis or anything so I don't know.

"It lasts longer this way!" - my mother

Natalia
June 4th, 2009, 08:22 PM
I dont use poo anymore but i would just keep a salon bottle in the shower and mix up what i need. Takes 2 minutes tops and you dont have to worry. If it were a comercial poo with traditional chemicals and preservatives i wouldnt worry as much as say if you were doing it with an aubrey poo.

ktani
June 4th, 2009, 08:22 PM
The amount of preservatives in a product is calulated to the amount of water and other ingredients in it (per 8 or 10 oz for example), so I agree with the information.

However, that is about diluting quantities of shampoo and using the diluted version over time. You can always dilute an amount of shampoo for immediate use and do so without having to worry about it.

teela1978
June 4th, 2009, 08:24 PM
I think it's possible... and to be honest, it's part of why I dilute mine fresh each time... but it's probably just me being a little ocd.

Fractalsofhair
June 4th, 2009, 08:31 PM
Perhaps if you kept it in a warm place heavily diluted for a while. A day or two in a slightly diluted mixture shouldn't cause issues, and you are rinsing it off after, thus removing bacteria. If you have a compromised immune system, I would suggest diluting it fresh every time.

manderly
June 4th, 2009, 08:44 PM
I would guess that if you had a diluted poo sitting in your shower untouched for a few months it would be squidgy. But my assumption is that the majority of people only dilute small amounts (week's worth) or on an as-needed basis. :shrug:

I can't see how that would be harmful at all.

Euphony
June 4th, 2009, 09:10 PM
The amount of preservatives in a product is calulated to the amount of water and other ingredients in it (per 8 or 10 oz for example), so I agree with the information.

However, that is about diluting quantities of shampoo and using the diluted version over time. You can always dilute an amount of shampoo for immediate use and do so without having to worry about it.
I'm a huge proponent of preservatives - yes it is true for the reasons ktani mentioned. In formulating anything - conditioner, shampoo, lotions etc the preservative is calculated at the amount of oil to water - if something is not an oil it is a water. Mixing water is unable to fight off bacteria or any nasties on it's own, oil however can/does - since bacterias do not grow in oil. But anytime anything non oil is introduced a proven preservative in the correct proportions must be added so nasties don't grow.

Diluting at each use is fine, there's not enough time for nasties to grow. But diluting and leaving it even for a day can cause problems unless it was over-preserved in which case is neglegence on the formulators part.

Buddaphlyy
June 4th, 2009, 09:51 PM
This is slightly alarming to me. I diluted about 2 oz of a SLS based shampoo with 6 or 7 oz of water and have left in the shower daily for about the past 2 weeks. I've only used it twice, but hope to be finished with it by the end of the month (just in case). I do look at the bottle everyday and I haven't noticed any changes in it. It also still smells like the shampoo when I open it. Should I be worried?

ktani
June 4th, 2009, 09:56 PM
This is slightly alarming to me. I diluted about 2 oz of a SLS based shampoo with 6 or 7 oz of water and have left in the shower daily for about the past 2 weeks. I've only used it twice, but hope to be finished with it by the end of the month (just in case). I do look at the bottle everyday and I haven't noticed any changes in it. It also still smells like the shampoo when I open it. Should I be worried?

I don't think that you should be alarmed but I would not use the rest of it. The amount of time an open bottle of water is still good refridgerated, is about 2 weeks (http://ask.yahoo.com/20031125.html).

Just because the solution still smells ok doesn't mean that things are not starting to multiply in there that you might not be happy with. Standing water is a breeding ground for bacteria.

Delila
June 4th, 2009, 10:00 PM
I've had diluted shampoos in steady use for quite some time, and I've had no issues of any kind whatsoever with product degradation, or whatever creeping nasties the article seems to think would be lurking just for the chance to erupt from your shampoo.

The mixture is still quite strong. It's not as though it were dilute enough to be 'stagnant water plus some shampoo', it's got plenty going on there that makes the environment quite unfriendly for whatever might tend to grow in plain water left to stand.

Buddaphlyy
June 4th, 2009, 10:04 PM
I don't think that you should be alarmed but I would not use the rest of it. The amount of time an open bottle of water is still good refridgerated, is about 1 week.

Just because the solution still smells ok doesn't mean that things are not starting to multiply in there that you might not be happy with. Standing water is a breeding ground for bacteria.


Eeekk, I totally did not know that :shocked:. It's been a long time since I've been in a science class, lol. I guess I will pour it out then. I'm glad this thread was started though because I was going to use the stuff tomorrow to make my hair smell good because I liked the scent of the shampoo.

ktani
June 4th, 2009, 10:10 PM
Eeekk, I totally did not know that :shocked:. It's been a long time since I've been in a science class, lol. I guess I will pour it out then. I'm glad this thread was started though because I was going to use the stuff tomorrow to make my hair smell good because I liked the scent of the shampoo.

I never really thought about it either in terms of diluting liquid soap or shampoo and I used to dilute the liquid soap I used all the time. I happened to come across an article on the subject and it made me rethink what I was doing. It really depends on how much you dilute a product and how fast you use it up. Leaving a diluted product sit at room temperature for weeks? Not a good idea.

Buddaphlyy
June 4th, 2009, 10:18 PM
I never really thought about it either in terms of diluting liquid soap or shampoo and I used to dilute the liquid soap I used all the time. I happened to come across an article on the subject and it made me rethink what I was doing. It really depends on how much you dilute a product and how fast you use it up. Leaving a diluted product sit at room temperature for weeks? Not a good idea.

That was my concern too. Our shower's temperature changes several times during the day (very hot when someone's using it then becoming cooler when we're not) and the solution was only being used once every 7-10 day. And now that I think about, the solution was actually becoming more potent as I used it, i.e. it would tingle more if I accidentally got some in my eye. And it was surprising that I put so much water in it and the shampoos scent still was very much there.

ktani
June 4th, 2009, 10:22 PM
That was my concern too. Our shower's temperature changes several times during the day (very hot when someone's using it then becoming cooler when we're not) and the solution was only being used once every 7-10 day. And now that I think about, the solution was actually becoming more potent as I used it, i.e. it would tingle more if I accidentally got some in my eye. And it was surprising that I put so much water in it and the shampoos scent still was very much there.

Even diluted, the preservatives would help somewhat but they are calulated as I said for the original amount of water, not extra. I never suffered any major consequenses from my diluted hand soap but I no longer dilute it and my skin is less itchy than it used to be.

Delila
June 5th, 2009, 12:01 AM
And for what it's worth, assuming you folks don't have me on ignore, Queen Helene Mint Julep shampoo is designed to be diluted, or used straight.

Arctic
June 5th, 2009, 12:31 AM
I haven't read all the replies, but this does sound possible to me. I have read that it's usually water that makes product go bad, and perservatives are used to make water based products last longer. I have always found "eww" when members say they dilute a shampoo in a bottle and use it while it lasts (which might be a long time).
I lack scientific terminology, I apologice, but basically, water is what makes product inviting for bacteria. That's what I've read but then again I am not chemist and have no knowledge other than reading little here and little there.

I would also think that diluting it as needed is okey.

HotRag
June 5th, 2009, 12:56 AM
I say like several else her; I would not dilute more than what I am going to use for one or most two washes.

If one makes own shampoo, one can make an amount for one wash/one week (I wash once a week), and then not use any preservatives at all. I haven't done this, because I am to lazy to make schampoo for every time (hmm... I do IHW and that's ok to do every week... hmm... time to rethink about the home made shampoo)

If a schampoo is designed to be diluted and can stay diluted for long time, I would think it has more preservatives in it.

Jeni
June 5th, 2009, 01:40 AM
I've always wondered about this ( I don't dilute btw). I'm sure many people dilute shampoo and use if just fine for weeks on end. I kind of view that as the same thing as eating raw cookie dough/licking cake batter from the spoon. Were not suppose to eat raw eggs since they can make you sick but I have been doing it for years and never had a problem. When I was in Germany the family I lived with regularly left lunch out (were talking stuff with meat in it) on the stove all day and night and then we would eat it for lunch the next day...yea I was sure I would was going to get sick and yet I never did (years of eating military food??).

If you have been using diluted shampoo for awhile and never had a problem that doesn't mean you wont in the future. However if it were me and I was happy with my current routine I cant say I would change it until/if I did have a problem, but then I like to live on the wild side.

Fethenwen
June 5th, 2009, 02:26 AM
Good to know. I usually dilute the shampoo if I use it. But not the whole bottle, just a few drops at a time.

Gulbahar
June 5th, 2009, 03:58 AM
I use to make my own cosmetics so I know quite a bit about preserving them. As long as your shampoo is not of the super organic kind there is enough preservative in it to keep it ok for at least two years. There are regulations about that and I don't know exactly how long a producer of cosmetic has to guarantee the freshness of his product but for conventional cosmetics we are talking years.
So if you add water of course you also dilute the preserving agent(s) but this only shortens the time they will be able to keep the germs at bay - may be now it's six months or three, but still nothing to worry about. So don't panick! Conventional products usually are so heavily preserved that adding some water is nothing that will turn them into a breeding ground for germs within a week or two.
But anyway, why not simply diluting only the amount of shampoo you need for one washing? That's what I used to do when I still used shampoo.

Lamb
June 5th, 2009, 05:18 AM
Many thanks for the replies!
I think I'll just not let dilutions sit around for weeks, if that's the case. And use distilled water, JIC. I thought it was as Gulbahar posted... and Delila, I think if a shampoo is designed to be diluted it probably contains the necessary amount of preservatives for it!
At any rate, it's good to know. I don't need biohazards in the shower. :silly:

embee
June 5th, 2009, 06:28 AM
My guess is somebody wants you to use full strength (probably everry day, lather up twice) so they can sell more 'poo.

heidi w.
June 5th, 2009, 09:19 AM
If I dilute my shampoo, I do it right before application, in fact, in the palm of my hand!

It's easy to do.

heidi w.

Gulbahar
June 5th, 2009, 09:46 AM
I've always wondered about this ( I don't dilute btw). I'm sure many people dilute shampoo and use if just fine for weeks on end. I kind of view that as the same thing as eating raw cookie dough/licking cake batter from the spoon. Were not suppose to eat raw eggs since they can make you sick but I have been doing it for years and never had a problem.
:bigeyes: No raw eggs allowed? Oh boy! So I must have poisoned myself all my life with homemade mayonnaise and tiramisu! :D But seriously, as long as the eggs are fresh and from healthy chicken there is no problem whatsoever with eating them raw.


When I was in Germany the family I lived with regularly left lunch out (were talking stuff with meat in it) on the stove all day and night and then we would eat it for lunch the next day...yea I was sure I would was going to get sick and yet I never did (years of eating military food??).Yeah, we Germans are soooo dangerous people...... :eyebrows: You know, in many cultures (South Asia for example) it is totally normal to cook a big pot of something and leave it for everyone to eat _without_ putting it in a fridge. No problem at all, although they have a much hotter climate than Germany. But it is cooked, which sets the germ level to almost zero and it takes some time for the little buggers to regrow enough to be dangerous. Also when you reheat the food thoroughly you kill what little might have developed by then. We are surrounded by millions of germs anyway. Being careful is a good thing and very important but keeping it in proportion as well. ;-)

spidermom
June 5th, 2009, 11:11 AM
I have an empty squirt bottle and mix my shampoo/water solution just before I use it, so no worries.

ratgirldjh
June 5th, 2009, 11:16 AM
Geez - I dilute everything and I've never had any problem. AND I have a very sensitive nose and I'm sure I could tell if something had gone bad! Once I threw away an entire bottle of sesame oil I had just bought because I could smell it had gone off.... I know - I should have returned it... :(

jivete
June 5th, 2009, 12:41 PM
I think you'd be fine storing it until the chlorine demise. Chlorine disenfectic only lasts so long before it breaks down and is no longer strong enough to keep tap water clean. I think in our system it's about 2 weeks, how long it takes to get from the treatment plant to the farthest corner of our distribution system.

I'm not a chemist though, so I don't know if the chlorine breaks down when it gets exposed to air since our water distribution system is all pressurized pipes and air in pipes is bad, but for different reasons.

Demetrue
June 5th, 2009, 12:54 PM
It never occurred to me to dilute an entire bottle of shampoo and just let it sit for weeks or months. I dilute exactly what I need each time I shampoo. I will fill up a cup with catnip tea or warm water, add a few drops of shampoo and swish it around until it foams up and then pour ir over my already wet hair.

Maelyssa
June 5th, 2009, 05:24 PM
Well that just sounds outright gross!
Luckily I haven't been doing mass diluting for some time but I will keep this in mind for future use 'just in case' it's accurate.
Thanks for the info!

morguebabe
June 5th, 2009, 06:24 PM
Like ktani said the amount of preservatives is based on the formula. I mean I dilute my poo but in a little jar and use it right away. I wouldn't keep diluted anything.

Jeni
June 5th, 2009, 11:43 PM
:bigeyes: No raw eggs allowed? Oh boy! So I must have poisoned myself all my life with homemade mayonnaise and tiramisu! :D But seriously, as long as the eggs are fresh and from healthy chicken there is no problem whatsoever with eating them raw.
Yeah, we Germans are soooo dangerous people...... :eyebrows: You know, in many cultures (South Asia for example) it is totally normal to cook a big pot of something and leave it for everyone to eat _without_ putting it in a fridge. No problem at all, although they have a much hotter climate than Germany. But it is cooked, which sets the germ level to almost zero and it takes some time for the little buggers to regrow enough to be dangerous. Also when you reheat the food thoroughly you kill what little might have developed by then. We are surrounded by millions of germs anyway. Being careful is a good thing and very important but keeping it in proportion as well. ;-)

Well I get my eggs from the store so they aren't usually that fresh (I miss my chickens in Germany!). That being said I have never gotten salmonella from eating cookie dough/brownie batter/cake batter and until I do I will continue to chow down on it (YUM!).

Y'all Germans (with your freaky non refrigerated milk) do love to live on the edge!! :D I grew up refrigerating everything so seeing food left on the stove overnight was a big shock to me. I never got sick and the family said they had always done it like this so there ya go. I cant say I would leave food out but to each their own. When i tell people here about it they look at me like I have grown a third eye, we Americans like to refrigerate things apparently...

Autumnberry
June 5th, 2009, 11:54 PM
As long as your shampoo is not of the super organic kind there is enough preservative in it to keep it ok for at least two years.

Yeah, I think I learned my lesson recently, when one of my Aubrey Organics shampoos started to smell after 6 months. And I hadn't diluted it. Yuck! I'll be more careful with the quantities purchased in the future :rolleyes:.

nowxisxforever
June 5th, 2009, 11:58 PM
I never dilute shampoo until I'm about to use it anyway :shrug:

I don't either. It's easier not to, since there aren't any bigger containers in the house than my shampoo bottle!

EdG
June 6th, 2009, 10:27 AM
I too dilute my shampoo just before use. :)

I share the concern about things eventually growing in a solution that's mostly water.
Ed

Drynwhyl
June 6th, 2009, 11:37 AM
I never dilute shampoo until I'm about to use it anyway :shrug:
Yep... Don't dilute the whole bottle, just put a bit in a glass and add water for every wash. I never actually thought of doing it all at once xD

Xandergrammy
June 6th, 2009, 11:38 AM
I always water down my shampoo, but in a little squirt bottle before each wash. The original strength is maintained in the big bottle.

Nevermore
June 6th, 2009, 12:12 PM
I have an empty squirt bottle and mix my shampoo/water solution just before I use it, so no worries.

Same.

As for the milk that's shelf stable, I believe it's irradiated or similar. It's not normal milk, iirc.

enfys
June 6th, 2009, 12:30 PM
It never occurred to me to dilute an entire bottle of shampoo and just let it sit for weeks or months. I dilute exactly what I need each time I shampoo. I will fill up a cup with catnip tea or warm water, add a few drops of shampoo and swish it around until it foams up and then pour ir over my already wet hair.

This is exactly what I do, but I use a bottle not a cup.

Not once have I have thought to dilute it in advance. Maybe because I use it as a foam? I was considering diltuting my ACV but wouldn't have been able to get a bottle big enough, never mind the stagnant water.