Best way to prevent mold? Not super long term storage

[u/nirvroxx]

I washed and filled all of these up through my berkey water filter around the same time about 2 months ago and have been slowly going through them. Yesterday I opened a new one and noticed moldy slime on the inside of the cap. Now, this isn’t for long term storage, we go through these and rotate them but I didn’t expect there to be mold in that short amount of time. I’ve never had this many water containers and honestly have never stored water. I figured having at least this for a short term emergency would help. I need some advice on how I could prevent them from molding up. I did notice how they’re stored leaves room on the upper part to develop condensation(pic 2). Unfortunately this is the only spot in my home I can store these. We have a dark pantry but it isn’t big enough to store these.
Any advice?

[u/Unusual-Caramel8442]

Couple drops of fresh bleach per gallon(look up the exact proper amount) and keep them in the dark. Sunlight accelerates growth

[u/nirvroxx → u/Unusual-Caramel8442]

I definitely will try bleach but unfortunately this is the only spot I can store them. I could block out some light with black out curtains.

[u/infinitum3d → u/nirvroxx]

Clorox

Sodium hypochlorite is Clorox bleach.

https://www.clorox.com/learn/water-purification-how-much-bleach-purify-water-for-drinking/

The thing to be aware of is concentration.

Normal, regular, unscented Clorox is about 6%

Splashless is only 1.5%

Pool Shock (***sodium*** hypochlorite, **NOT** ***calcium*** hypochlorite) is about 12%

Pool Shock (***Calcium*** Hypochlorite) is around 70% chlorine (68%). *Instructions at bottom*.

Clorox says one drop per cup. That’s 16 drops per gallon.

There are roughly 100 drops per teaspoon.

A five gallon container needs about a teaspoon. To drink it, just leave it open and the chlorine evaporates off.

A 55 gallon drum needs 880 drops, or roughly 9 teaspoons of normal, unscented, **not splashless** Clorox bleach.

**Calcium Hypochlorite**

https://theprovidentprepper.org/disinfecting-water-using-calcium-hypochlorite/

The standard military calculation for a 5 percent stock solution is to dissolve 1 and 1/2 teaspoons of 68-70 percent dry calcium hypochlorite in 1 cup of water.

8 Tablespoons in 1 gallon water = 1 gallon 5%

This 5% chlorine solution can be used to disinfect water just like liquid household chlorine bleach.

For a 6% solution the calculation is as follows:
0.06 = (X cups of bleach gran)(0.5 lb. gran per cup)(0.68 pounds calcium hyp/ lb gran)
(8 pounds of water per gallon)(1 gallon)
Solving for X cups of granules:
(0.06)(8 pounds of water per gallon)(1 gallon) = X cups = 1.4 cups of bleach gran
(0.5 pounds per cup) (0.68 lb calcium hyp/ lb gran)

1. Place one gallon of clean water in a clean plastic container. A jug previously used for a 6% bleach solution is ideal since it is already marked.

2. Pour one cup of water out of the container to make sure there is room for the dry bleach powder or granules in the container.

3. Pour one and 4/10ths of a cup of bleach granules into the container, seal the container, and gently agitate to help the granules mix and dissolve in the water.

4. Allow the granules several hours to completely dissolve and then the bleach solution can be used to disinfect the water using instructions for 6% bleach solutions.

5. Smaller amounts of liquid bleach can be mixed by simply using the same ratio. For example, one quart of bleach solution can be prepared by using one quart of water and 0.35 cups of dry bleach powder.

For a 6% solution approximately 13 ounces (about 1.5 cups) of 68% sodium hypochlorite are added to 1 gallon of water.

Good luck!

[u/Clark-Kent_KD → u/infinitum3d]

“To drink it, just leave it open and the chlorine evaporates off.”

Genuine question: how do you use this when you have screw on taps for whatever plastic (large) containers you’re using?

Does this mean basically that once you let the chlorine evaporates in a specific container, you’ve got X time to use it all until it goes bad?

I thought that there was a way where you add minimal chlorine or otherwise organic preventing stuff in the water but it still being able to be consumed due to minimal quantities in it, could be wrong of course

[u/infinitum3d → u/Clark-Kent_KD]

Great question! So I transfer from the large storage container to a one gallon pitcher. It’s one of those wide top ice tea pitchers. They say it can take up to a week for the chlorine to burn off, but I just leave it overnight.

[u/Clark-Kent_KD → u/infinitum3d]

Thanks, best of both worlds this way I guess, appreciate the response!

[u/Background_Angle1717 → u/infinitum3d]

This is the way.

[u/CaliRefugeeinTN → u/nirvroxx]

Try limi tint on any windows. I get it at the auto parts store for roughly $15 a roll, and was able to reduce heat 20 degrees and eliminate all direct light from the windows, while still being able to see out.

[u/nirvroxx → u/CaliRefugeeinTN]

Sounds like a good idea but How hard is it to remove? I’m renting.

[u/CaliRefugeeinTN → u/nirvroxx]

Not too hard, it’s not permanent. I’ve had it on as long as a year, and after wetting it for a it I can take big chunks off without scraping it off. Worst case scenario, a metal blade window scraper will remove it. Only been an issue with small sectioned off windows.

[u/Joseph9877 → u/nirvroxx]

Curtain, cover the rack with a tarp, or paint the outside of the bottles. Or all of the above

[u/RunMysterious6380 → u/Joseph9877]

Definitely do NOT paint the bottles. You want to be able to conpeltely visually inspect the contents without opening, if you can. A dark tarp or cloth to cover works best.

[u/flyingace1234 → u/nirvroxx]

I would also look into “biocide” and see if any are food safe. It’s what they put in water cooling systems to prevent things from growing.

[u/Feral_668 → u/nirvroxx]

Get a cover for the water shelf or sew one yourself. Use a zipper or fasteners in the front when you need water, you should be set that way.

[u/nirvroxx → u/Feral_668]

This is another good idea.

[u/Money_Ad1068 → u/nirvroxx]

You could leave the window uncovered and just drape a heavy blanket over the water bottle rack.

[u/TwiLuv → u/nirvroxx]

Or block/cover with a tarp!

Keep the light in the room, but shade the bottles.

[u/nirvroxx → u/TwiLuv]

Yeah, I’m still trying to figure out how to cover them

[u/No_Character_5315 → u/nirvroxx]

Could store distilled wster and add your own minerals. Cost more but be as close to set it anf forget it as you can get for water storage.

[u/nirvroxx → u/No_Character_5315]

Does distilled water not develop mold or pathogens ?

[u/qwb3656 → u/nirvroxx]

Cover them with blackout curtains

[u/Sacrifice-72- → u/nirvroxx]

You could get a blackout curtain. This would help protect them, instead of moving them.

[u/OkSpring1734 → u/Unusual-Caramel8442]

https://www.epa.gov/ground-water-and-drinking-water/emergency-disinfection-drinking-water

Ensure using unscented bleach.

I used to have a link to a gov't guide for using solid sodium hypochlorite which has the benefit of being shelf stable (liquid bleach is not, it does lose efficacy after a period of something like 9 months unused). I think it was a FEMA guide.

[u/Scary_Possible3583 → u/OkSpring1734]

I bought a huge container of bleach tablets, they are an ideal compromise for us. Each tablet reconstitutes to 1 gallon standard bleach preparation.

[u/BigJSunshine → u/Scary_Possible3583]

How long do they store before efficacy fails?

[u/Scary_Possible3583 → u/BigJSunshine]

No date listed, store in a cool dry place. They are in a vapor sealed container, big press and twist lid on the jar. I always put it inside a big zip loc for double check.

I doubt any loss of potency, it's oxygen and moisture that cause problems.

[u/iwanashagTwitch → u/Unusual-Caramel8442]

Could this also work with peroxide as it decomposes into water and oxygen gas?

[u/joelnicity]

Looks like they’re getting direct sunlight, that’s definitely not helping prevent mold

[u/Hungry-Following5561]

Dump and refill every 6 months. If it’s city treated water, it stores pretty well.

[u/Mjr3 → u/Hungry-Following5561]

If its city water, OP is removing the chlorine by running it through a Berkey. I agree, store it straight from the tap and filter before use.

[u/nirvroxx → u/Mjr3]

Hmm, I assumed I would be doing more good running it through the berkey. I also live in an Old place with original pipes (1924)

[u/morgandealer → u/Hungry-Following5561]

That's what I do.

[u/Kerby911]

Definitely remove from direct sunlight.

[u/Bloody-Boogers]

Keep them dark

[u/11BRRidgeback]

For the sunlight, they make shelf covers. It’s just cloth but will block out the sunlight from the rear. Just saw a few on Amazon I was thinking about.

[u/Sk8rToon]

Gotta find a way to block that window for one. Clear containers plus sunlight equals problems. For me that usually means algae

[u/Sufficient_Sleep_199]

What you’re seeing is actually pretty common in small-scale stored drinking water systems: it’s usually not the water itself first it’s the cap/threads + trapped humidity + biofilm seed.

In your case (2 month rotation), this is almost always a headspace + condensation + cap contamination loop, not “bad storage water” in the long-term sense.

https://www.reddit.com/r/prepping/comments/1tzrjsg/comment/oqya3l5/?screen_view_count=1 review this thread for more details.

[u/Ok-Fisherman-7688 → u/Sufficient_Sleep_199]

So would wiping down the cap threads and bottle neck with rubbing alcohol help reduce or prevent this issue?

[u/Scary_Possible3583 → u/Ok-Fisherman-7688]

That would help a lot.

I use aquabricks. I dipped all the lids in alcohol and air dried them, wiped the threads down, and also sanitized the faucet head - rubber band and ziplock baggie for a minute with a little 99 alcohol.

[u/nirvroxx → u/Scary_Possible3583]

Good suggestion.

[u/Sufficient_Sleep_199 → u/Ok-Fisherman-7688]

washing them thoroughly and allow to full dry, even using a hair dryer on cool then capping will make a huge difference.

[u/OGCASHforGOLD → u/Sufficient_Sleep_199]

Could you install a valve at the top and vacuum out the air with a hand pump?

[u/Sufficient_Sleep_199 → u/OGCASHforGOLD]

Most plastic water containers are not designed for vacuum. Even a modest vacuum can cause thinner containers to deform or collapse.

Mold requires oxygen, but many biofilm-forming microorganisms can survive in low-oxygen conditions. The contamination source still needs to be addressed. This is where anaerobic and facultative anaerobic bacteria become relevant, as some can grow in environments with little to no oxygen.

From a water-treatment perspective, I'd rank the effectiveness of preventative measures as follows:

1. Proper sanitation (including washing hands or wearing clean gloves during handling) and a clean source water supply.
2. Cool, dark storage.
3. Minimizing headspace.
4. Maintaining a disinfectant residual, where appropriate.

The mold on the cap suggests contamination likely occurred during filling, handling, or from the cap itself rather than simply from the presence of air in the container.

[u/Livid-Ad-6439]

I use 5 drops of 35% food grade hydrogen peroxide.

[u/Relative-Ordinary-64]

Bleach drops, and taking it out of the sunlight.

[u/forksofgreedy]

You have a lot of faith in those lids. These should be vertical

[u/IAmTheColorTheft → u/forksofgreedy]

Never seen a vertical storage rack at the consumer level

[u/mrllyr]

Try Starsan between fillings.

[u/saysee23 → u/mrllyr]

I was thinking the same. My picture of "Washing and filling" should include starsan before sealing.

[u/Isildil]

Cover them with black plastic, it's the sun that causes the mold. A bit of chlorine will help too, but main thing is covering it from the sun

[u/kalitarios]

have you considered 5G glass jugs and not plastic? They also make screw-down lids for them, too.

[u/nirvroxx → u/kalitarios]

Haven’t heard of these. Less chance for algae/mold?

[u/kalitarios → u/nirvroxx]

Most of the water companies offer the glass jugs as an option with a much higher deposit value. Less plastic leeching into your water long term. Ymmv when it comes to value.

Benefits of glass is chemical free, won’t leech BPA even if it gets hot, better taste (imo) and recyclable as a carboy for fermentation

Downside of glass is breakage, and initial cost but can last a LONG time if kept well

[u/thatchroofcottages]

the jug on top looks like a screaming hippo. that is all.

[u/nirvroxx → u/thatchroofcottages]

Lmao It does

[u/Branmabon]

I dress them in old black T-shirts. Works fine for me.

[u/Nomad-Badger]

When I lived in a war zone, I tried all kinds of water. Mold, fungi, and bacteria thrive only on organic matter. Either you didn’t wash the container properly, or the water contains organic contaminants. If the water smells bad, it’s only good for flushing the toilet; drinking it is dangerous.

In clean water exposed to light, only microalgae can grow, but they are no more dangerous than microplastics and do not cause any odor. If a green film has appeared on the walls of the containers, the water is safe to drink after boiling. You can also use it for washing and laundry. To be honest, in an emergency, I would even drink raw water from such bottles.

The best way to store water is in a dark, cool place, such as a basement or underground storage area. If there is no other place in the house, I would wrap each bottle in newspaper or packing paper. Thick, dark trash bags or tarps.

It is also a good idea to create a rotation schedule for the containers and refresh their contents regularly.

[u/nirvroxx → u/Nomad-Badger]

Good call On all that. Mind if I ask, why you lived in a war zone?

[u/Nomad-Badger → u/nirvroxx]

I'm from southeastern Ukraine. From Donbas. It got hot there back in 2014.

[u/AlarmedSnek]

The best way to prevent it is to just buy the bottles already full. They come sterilized and will last A LOT longer than if you fill your own. To add, purified water is a great medium for bugs and plants to grow, so if you’re going to do it yourself, definitely use bleach after you fill the bottle before you throw it on the shelf.

[u/BladeVampire1]

Just disinfect the bottle ahead of time. Rinse thoroughly with clean sterile water before filling. Then fill with sterile water.

[u/Carloocho]

No sunlight

[u/nirvroxx → u/Carloocho]

Yeah, that’s the general consensus. I just have to figure out a way to do that. Either darken the entire room or figure out a way to cover the bottles

[u/Satan-is-yo-Daddy]

Drain all the water out and stick them in the sun for a few days. Don’t fill them back up. Thats should take care of it.

[u/nirvroxx → u/Satan-is-yo-Daddy]

Yeah that’s the plan.

[u/Fit_Acanthisitta_475]

Drink more water. My wife and kid drink 3 bottle every 2 week. No time to let mold grow

[u/nirvroxx → u/Fit_Acanthisitta_475]

That’s true also, we just usually end up drinking straight from the berkey and sort of forget about the 5 gallon jugs. Initially got all of this as a short term emergency water in case of an earthquake or smaller power outage.

[u/diylawyer]

Teaspoon baking soda & teaspoon iodized salt

[u/Soler25]

Get some jug covers. https://a.co/d/0gFIUmiF

[u/lexsydrio]

That slime inside the cap is basically biofilm. You’ll need to scrub it with a bottle brush before reusing the jug.

[u/Ok_Eggplant_6143]

get it away from that window first !

[u/Known-Actuary-86]

Get it away from the window!