If your water source is uncertain, you should treat it first before drinking it.
One way to treat water for drinking is to add a small amount of Regular Bleach (chlorine). Here’s how much regular bleach to add:
(details below)
One best way to purify water for drinking is to boil it for 1 minute.
Once the water has reached a rolling boil, it has become safe to drink.
Note that if the water source had been contaminated with chemicals, boiling it or otherwise treating it will NOT assure that the chemical is removed.
Know your water source as best you can.
Another way to purify water is to use a small amount of Regular liquid bleach.
Use Regular household bleach, with the only ‘active’ ingredient ‘sodium hypochlorite’.
UPDATE: For many years Regular bleach contained a concentration of 5.25% sodium hypochlorite. Newer ‘Regular’ liquid bleach (which has been available for several years) now contains a concentration of 8.25% sodium hypochlorite (about 57% more than the original bleach formula).
(I have listed both amounts below for your reference.)
Having recently determined how much bleach to add to a 50-gallon water tank to purify it for safe drinking, I’ve put together the following charts for your reference.
One old ‘saying’ – a way to remember for small quantities:
“You must be 21 to drink”
2 drops bleach per 1 quart water
Mix the following amount of bleach with water, and wait 30 minutes for it to work. The water should have just a ‘hint’ of chlorine smell.
Water – Bleach Ratio For Purification
(Bleach containing 5.25% Sodium Hypochlorite)
numbers are ’rounded’
This will initially produce ~ 5 ppm chlorine
1 Quart water, 2 drops bleach
1 Gallon water, 8 drops bleach
5 Gallons water, 1/2 teaspoon bleach
10 Gallons water, 3/4 teaspoon bleach
50 Gallons water, 4 teaspoons bleach
Water – Bleach Ratio For Purification
(Bleach containing 8.25% Sodium Hypochlorite)
numbers are ’rounded’
This will initially produce ~ 5 ppm chlorine
1 Quart water, 1 drop bleach (1.3 rounded)
1 Gallon water, 5 drops bleach
5 Gallons water, 1/4 teaspoon bleach
10 Gallons water, 1/2 teaspoon bleach
50 Gallons water, 2-1/2 teaspoons bleach
Read more: Smallest Berkey Countertop Water Filter – Specs
NOTES:
The initial chlorine level (ppm) will drop when interacting with water and organic contaminants (it’s doing it’s job). This may occur slowly or precipitously.
If the water is cloudy, and if you still cannot smell any chlorine in the water after having let it sit for 30 minutes (there should be a hint of chlorine smell), the CDC (Centers for Disease Control) advises that you consider a 2nd round of treatment.
According to the EPA, the maximum recommended ppm (parts per million) of chlorine bleach in drinking water is apparently 4 ppm.
Generally speaking, water that has a chlorine level of 4 ppm would smell very strong of chlorine, whereas a ‘hint’ of smell indicates a level well below that. A chlorine test kit is the only true way to know for sure.
Bleach will lose its potency (fairly quickly) over time. Generally, 6 months to a year after its expiration date may result in half strength.
Continue reading: How much bleach for disinfecting surfaces (food & non-food surfaces)
Good Information Ken but folks need to remember that the above information is for clean water. Organic material adsorbs a lot of chlorine, so prefilter your water with at least a tee shirt before adding bleach.
If the water is very dirty, yes, pre-filtering through cotton or other means will enable more efficient chlorine purification of organics that remain.
Also, avoid scooping water near the bottom of a source – which may kick up some sediment. Scoop from the top.
Also, as I said above, the smell test is recommended. If there’s a hint of chlorine, you’re likely good to go. If not, add more.
Note: It is recommended that you wait 30 minutes for better assurance of effectiveness prior to drinking, especially if the water is cold.
Invest in a couple packages of coffee filters to strain water through first
For water purification for drinking, chlorination with bleach is not completely effective against Cryptospridium though it is against Giardia. Both of these protozoans can sometimes be found in both springs and vertical wells in the US. The only effective water purification methods for Crypto are boiling and microfilters. Microfilters do not generally remove 100% of viruses but this is not necessarily a problem in the US. All waterborne enteric viruses affecting humans occur solely in humans, thus animal waste doesn’t present much of a viral threat. Keep your source free of human waste and a microfilter should suffice. Easier to do now but could be more of a challenge in SHTF. Keep your bleach handy for viral contaminants and your microfilter for most everything else.
And now days “they” say you’ll die from drinking from a Garden Hose….
Good reminder Ken on the quantity of Bleach to Water ratios.
Another idea is to store Pool Shock, much different ratios though, make sure to store it properly, Chlorine fumes in concentration are bad mojo for sure.
Tis a wonder how I made it to 65 with all the stuff that’s now “bad for you” even Salt on my Rare Steak 🙁 🙁
NRP Pool Shock and some Evil Ingenuity can make an over run home temporally uninhabitable to run those Gimme Dats out for your attention. Look at it’s MSDS for details of this.
I call it the Sampson Jr. Option when you’d like to return to your home with minimum damage.
Hope you never need to do it but it is an pre-arranged option for bad times.
Come on, Bro…. everywhere I read, says 3 TABLESPOONS per 55 gallons.
If you’re going to publish stuff like this, get it right!
Scott R Switzer;
So no problem with the 1/2 per 10 gallons??? Yet 3 teaspoon full is 6 times the water, so 60 gallons?????
10 Gallons water, 1/2 teaspoon bleach
50 Gallons water, 3 teaspoons bleach
Hummmm, interesting for sure, maybe you need to “get it right”?
Hey Bro, 3 TABLESPOONS will certainly purify that barrel. In fact, disinfect it. However the chlorine ppm will be so high, I would hesitate to drink it at that potency. 3 TEASPOONS however will result in ‘about’ 6 ppm, depending on the water condition itself. Read the article.
Oh, how do I know? not only because of the math, but I do it myself, and measure it with a test kit. Just saying…
Thanks guys. Was just thinking I need to print this off.
Ken – what’s the ratio for making bleach from pool shock to get the right percentage/strength to use this chart? Be nice to have it all in one posting. Thanks!
One note ,,, the hotter the water (summer in jungle), the quicker the chlorine will dissipate. :o)
Thanks for pointing that out. Absolutely correct.
At the required rate, will it kill mosquitos, AND be safe to water my plants with?
Pam why would you treat the water you water plants with? Your plants do not need treated water. The treatment is to prevent-kill off nasty’s that cause Humans disease.
The shorter answer to your question is chlorine (bleach) treated water is not the best for your plants. Some plants wouldn’t mind others would be a bit stunted in my experience.
me2, the mosquitoes are eating me alive. I catch all rain water for 2 large gardens and the mosquitoes are winning at this point. Could I use a smaller ratio possibly?
Might look at “mosquito rings” on amazon
– Pamela Campbell,
Another source would be to go to your local farm and ranch store (Gebo’s, Tractor Supply, you-name-it) and ask for mosquito dunks. These are just little brown rings that you add to your reservoir and will kill the nymphs (also known as bloodworms) with a biological agent. Last resort, go by wally world and buy a couple of Bettas (also known as Siamese Fighting Fish) and they will eat them.
– Papa S.
Add mosquito netting to every single opening on you rain barrels
Water run off from asphalt roof to 55gal green water storage with a window screen over the top to filter out the roof run off just no, using it only for grass and non food plants, will bleach kill off the algae and other nasties if the air temperature is over 90 degrees?
Lori, yes it will. Since you’re not using this water for drinking, I would use more than what I’ve listed in this article – given the barrel’s storage conditions.
Ahoy Mr. Jorgustin. Your article was very helpful and written in a lucid style that even dummy tugboat captains can follow. So here’s my issue:
Our sewage treatment system (MSD) aboard the tug sits on top of a 2880 usg potable water tank. The MSD overflowed. I do not have any reason to suspect contamination. However, we do on occasion open the sounding tube on top of the tank to check its level. To be safe, I wanted to treat a completely full tank. I will not be able to flush the tank out, we will be drinking the water after treatment. The water is filtered twice between the potable tank and the coffee machine. What level would you recommend to be effective against any creepy-crawly that is presently living in my tank that will not give the water an overpowering scent of bleach??
P.S. It would take about 5-8 days to consume one full tank. We “top it off” at least once a week.
My question is, if you need one drop of 8% bleach for a quart of water, why would you need 6 drops for a gallon (which is 4 quarts.) Why not four drops to a gallon?
Marvin in Nashville,
It’s a ’rounding’ factor for the newer Bleach containing 8.25% Sodium Hypochlorite compared with the older (5.25% – 6%) concentration. The “1” is not exactly “1.0”, it’s greater.
I’m going to update this article to make this more clear. Thanks for your comment.
So, if you were just doing one quart, would one drop of 8.25% be enough?
I would do two drops for one quart of water, regardless of 5.25% or 8.25% regular bleach. Depending on the initial water quality and if there’s sediment in there, you may need more. Give it a smell test afterwards. You’re sniffing for a slight hint of chlorine smell, not ‘strong’. Hope that helps. Oh, don’t forget to let it sit for 30 minutes after shaking it up.
Thanks for the information. We are currently purifying water for our 72 hour kits and this is extremely helpful. Have a great day!
Reminder! “Once the water has reached a rolling boil, it has become safe to drink.” This is untrue – It may be free from contaminates, but let it cool down before drinking it. It’s not safe to drink boiling water. I know, common sense and all, but there may be some fool who will try it and end up in the hospital.