Purify Drinking Water With Bleach – How Much To Make It Safe

I’m going to tell you how much bleach to purify water. I have updated this to include bleach with 8.25% sodium hypochlorite (as the active ingredient). There are several ways to help make water safe to drink including boiling and filtration (see below). Regular household bleach is just one other method.

Note that we’re talking about purifying for organic pathogens (the most common reason for purifying water). However this will not mitigate toxic chemicals that may be in the water (uncommon).

Boiling Water

First, I would be remiss if I did not say that one best way to treat water for drinking is to boil it first. It only has to boil for about one minute.

According to the Wilderness Medical Society, water temperatures above 160° F (70° C) kill all pathogens within 30 minutes and above 185° F (85° C) within a few minutes.

So in the time it takes for the water to reach the boiling point (212° F or 100° C), all organic pathogens will be eliminated, even at high altitude.

Another effective way to make water safe to drink is to add a specific amount of regular household bleach. Depending on brand or concentration, regular household bleach contains between 5.25 and 8.25 percent available chlorine (liquid sodium hypochlorite), which will disinfect the water if added in the right amount.

So, again, how much bleach to purify water?


How to purify water with Bleach

If the collected water to be treated is cloudy and contains sediment, either scoop a new sample with less sediment, or strain it first through a makeshift filter (cloth bandana, t-shirt, coffee filter, etc..) or let it sit in the container allowing sediment to settle to the bottom. Gently pour off the clearer water on top.

Use regular liquid household bleach (any brand); however the only active ingredient should be sodium hypochlorite. Do not use bleach that contain soaps, perfumes, or dyes. Be sure to read the label.

‘CDC’ instructions for safe drinking water with bleach:

From the CDC, Centers for Disease Control, “If you don’t have clean, safe, bottled water and if boiling is not possible, you often can make water safer to drink by using a disinfectant, such as unscented household chlorine bleach”

How much bleach per gallon of water

Add 1/8 teaspoon (or 8 drops; about 0.625 milliliters) of unscented liquid household chlorine (5–6% sodium hypochlorite) bleach for each gallon of clear water (or 2 drops of bleach for each liter or each quart of clear water).

(5 drops using bleach with 8.25% sodium hypochlorite)

Stir the mixture well.
Let it stand for 30 minutes or longer before you use it.

How much bleach to purify water if it’s cloudy with sediment

Add 1/4 teaspoon (or 16 drops; about 1.50 milliliters) of bleach (5–6% sodium hypochlorite) for each gallon of cloudy water (or 4 drops of bleach for each liter or each quart of cloudy water).

(10 drops using bleach with 8.25% sodium hypochlorite)

Stir the mixture well.
Let it stand for 30 minutes or longer before you use it.

Rule of thumb… After initial dose, smell the water. If the water has a faint smell of chlorine, then it’s okay to use. If you cannot detect any chlorine odor, add another 8 drops of regular liquid bleach. Let stand, and smell it again. If you still cannot smell chlorine, discard it and find another water source.

>> Calibrated Glass Eye Dropper
(view on amzn)

>> Plastic Eye Droppers

We’re looking for 1, 2, or 3 ppm (parts per million). Chlorine test strips (or swimming pool test kit for chlorine) are useful to verify the chlorine level in the water. The maximum ‘safe’ level for drinking water according to the EPA is 4 ppm.

>> Chlorine Test Strips
(view on amzn)

>> Chlorine Pool Test Kit

Note that bleach has a shelf life, although you will probably not see a date on the bottle. Chlorine bleach may lose 20% to as much as 50% effectiveness within a year, so be sure to date your bottle upon purchase.

Notes about chlorine level for safe drinking water

The EPA recommends a maximum (no more than) 4 ppm (parts per million) of chlorine for safe drinking water.

A typical municipal water supply measured at the home faucet is typically between 0.2 and 0.5 ppm chlorine.

It takes 45 minutes to destroy Giardia Protozoan (common cause of diarrhea) with 1 ppm chlorine level.

‘WHO’ instructions for safe drinking water with bleach:

From the WHO, World Health Organization, “Chlorine is commonly available to households as liquid bleach (sodium hypochlorite), usually with a chlorine concentration of 1%”

Disinfection with chlorine is the most appropriate way of ensuring microbiological safety in most low-cost settings.

At least 30 minutes contact time should be allowed after the chlorine is added to the water before the water is drunk, to ensure adequate disinfection. The free chlorine residual (the free form of chlorine remaining in the water after the contact time) should be between 0.5 and 1.0 mg/l (0.5 ppm and 1.0 ppm).

The best water FILTERS for safe drinking water.

I have one in the house and one in the camper. It’s yet another way to purify water:

USA Berkey Filters

[ Read: Bleach – Water Ratio For Drinking Water ]

[ Read: How Much Bleach To Purify 50 Gallons ]


  1. Great tip!

    Also thanks for using both imperil and metric conversion rates – I’m hopeless with imperial as I am a child of the metric age.

    Thanks ken

    1. Metric makes it even easier. 1 ppm (part per million) is 1 ml in 1,000,000 ml. or 1 ml in 1,000 liters, but what they’re talking about is residual chlorine (how much is left after it has done its job of disinfecting). This really should be done with a test kit like the ones they use for testing pools. If that shows 1 to 1-1/2 ppm residual chlorine (after standing 1/2 hour), the water is safe to drink from the standpoint of parasites and bacteria. However, it does absolutely nothing for dissolved poisons like arsenic or lead (or almost any large concentration of heavy metals). If you ever have to get water from a lake or stream, it’s better to get it from a place that has living things in it. If it’s “too clean” there may be a reason. You can always strain or filter out algae or tiny bugs.

      1. hi-in many villages in india drinking water is not available. next to my organic farm is a stream containing 930 cfu/100 ml of e coli & 38 organism/100 ml of eschericha coli. as a social worker i want to supply 3 tankers of 5000 liters of potabe water to the nearby villages. can i use bleach or activated carbon or aeration in a tank for how much time or please suggest a simple low cost way to achieve this.
        many thanks in ADVANCE

          1) Clear water is a sign of pure water. Always drain long-standing pipes for 30 seconds to one minute before drinking! (Cheap remote motels?)

          2) 1 Gallon water is disinfected by 8-16 drops of regular household bleach (visually about 1/4 of a teaspoon) – double that for cloudy water. Shake and let stand 30 minutes. One teaspoon will disinfect 5 gallons. Immediately after treating, water must initially have a slight smell of chlorine. If it does not – repeat the process.

          3) Household bleach is relatively harmless. The smell or �waft� of chlorine is not bad: it indicates that water is treated and germ free. Once treated and disinfected, the chlorine smell will go away in a few days.

          4) Regularly used water from large tanks may be treated once or twice a month with 1 Oz. bleach per 200 gallons or 5 Oz. bleach per 1000 gallons.

          5) Long-standing water in tanks will be disinfected w/ 1 pint household bleach per 1000 gallons. (2500 gal tanks are fine with 3 pints.)

          6) Bleach effectively kills bacteria and viruses, stops smells and then breaks down. It’s effective germ killing alkaline property is completely neutralized very quickly. It does not stay chemically active in tanks for more than a few days. Most germs require sunlight to grow. Store water in the dark.

          7) If water is relatively clear: but has a noticeable smell of chlorine: it is drinkable, disinfected, and harmless. Humans need 2 quarts per day.

        2. Check Janjan on YouTube. He makes a filter with 4 55 gal plastic drums, sand, stone, charcoal, screen and float valve.

  2. Great article! Does this rule apply if I want to fill a 55 gallon plastic drum of water from the tap? Considering the tap water already has chlorine added to it as it is municipal water?

    1. Simply check your tap water with a chlorine test kit (a pool kit), and you will know what you have…
      So long as you’re at 1PPM – 4PPM(max), then you’re presumed ‘safe’

    2. Josh…. make sure the barrel is sterile /sanitized and the instruments you use to fill the barrel. I personally add a qt of bleach into the plastic drum, rolling it around, standing it on one end , then the other to sterilize it good. Then rinse. Once filled to over flowing with good tap water, I push on the side to expell any air bubbles before tightening bung plug.
      Two years latter, its still good water. The recommendation is to change the water every six months, but I haven’t done it yet? This water was for basic use, not drinking. I would drink it! Depends on the barrel that your are using and how long the water has been stored.

      1. Ok, thank you for the responses, this is great information. I just want to make sure I understand you clearly.

        1. Rinse the barrel thoroughly and then pour 1 quart of bleach into barrel. Swish around on both ends, let it soak well.
        2. Rinse the bleach out.
        3. Fill the barrel with water from the tap, squeeze sides to push any air out and then put in the bung plug (always funny saying that) and then good to go? Don’t add any bleach to the water or it should be safe as is?

        I’m not using this as my primary source for drinking water, but would be nice to have that option if needed. It’s mainly just as a backup to my primary drinking sources which are all just unopened drinking gallon water jugs from the supermarket.

        1. Josh….your equipment that you use for storage and processing, (barrel, hoses, water source) is the weak link in water storage. Also disinfect your hands! I personally use recycled 4L glass wine bottles that I get at the recycling center for immediate drinking water. I use 200L (53 gallon) barrels of water for dishwashing, laundry, toilets, misc………..
          Our well field is 11 miles away with 5 water towers. The water still test 1 ppm – 1.2 ppm chlorine residual at the faucet. Means, good water. Store all water in the dark. Sunlight and aeration destroys chlorine. If you have good water with too much chlorine( if you smell it, its probable too strong) let it set in the sunlight or shake it and then let chlorine dissipate. The water is disinfected with liquid bleach at the water plant. It was treated prior by gas. Chlorine is a poison to all life, do not over use!

        2. i bought 30 new food grade 55 gal. U.N. approved plastic drums from a company in Memphis that was going out of business. I have seen them advertised for up to $140.00 each. I guess if everything went down they would be worth it.

  3. Thanks for this information. I wanted to know for when I run out of bottled water and cannot get out often to purchase more water. Can anyone tell me what is the best type of bottled water to purchase?

    1. Depends what you mean by ‘best’. I’ve researched it awhile back to discover which of the many brands are considered more pure than others (better filtered and without impurities). I came across some test results, and for this particular test (which seemed legit), it was the Nestle brand (I have no affiliation with them). Taste is a matter of opinion, but with regards to survival, any of it is perfectly fine.

      1. Nestle water is not the best bottle water to choose from. It contains minerals in the water which is a nice word to cover up for chemicals. You can verify this on the back of the bottle. Their really isn’t a certain type of bottled water that is better than others. Just as long as its pure water with no minerals added. Also note storing lots of bottled water is usually not that practical if your prepping. Understanding the different ways of purifying water and having a nice water purification kit will help you the most. Your on the right track though. Water is definitely the most important item to store. Some people don’t understand all the food they have prepped will more than likely need to be boiled in water. I would recommend the cardboard boxes that have a liner in them to store your water. Their easy to rotate and easy to move around if needed.

  4. Someone posted the link to this page on an ultralight backpacking forum and I have to say you really nailed it. I’m an environmental engineer, my wife is an MD, we both backpack a lot and travel all over the world. It always bugs me when a National Park brochure or outdoor guidebook talks about boiling water for 5-10-15 minutes seemingly having taken the most conservative reference and then increasing it even more. You got all the high points right:

    Approaching boiling suffices. Chlorine works on almost everything. Remove sediments first. Smell it afterwards.

    And in the comments section, it is implied that initial chlorine treatment is good long-term storage. True. Let me be explicit: If you chlorine-treat water as you put it in a sealed container, there won’t be anything infectious in the water many, many years from now. The taste might be a little “plasticy” or rust might have formed depending on the container you used, but you killed any infectious organisms when you filled it with chlorinated water.

    And a suggestion: One tends to think of repurposing a 55-gallon drum, etc but those are tough to carry around in a pinch. Even 5-gallon water-cooler bottles can be too much for the weak or injured to handle without spilling a lot. But those 24 to 35-bottle flats of disposable drinking-water bottles? For about $3-$4 at Home Depot or the grocery store, it’s hard to find an empty container for less than $1/gallon and these come with treated water in food-grade containers and LOTS of redundancy.

    1. David, Thanks for supporting the information within the article and for your added commentary. Saving precious fuel is (can be) a BIG DEAL, and too many people are under the false impression that you must boil water for a lonnggg time before it’s safe to drink…

  5. Does anyone know…
    re the bottled water, such as flats of 36 bottles for purchase at costco, etc…

    these all have expiry dates on them usually six months to a year. do they genuinely expire/become hazard, or is this a marketin ploy to get you to pitch them?

    1. Lynn, regarding a marketing ploy, nothing would surprise me…

      Water that has been purified and made free from bacteria and then sealed in a container, will not go ‘bad’. I suspect that any date would imply a change in overall taste. The water will taste more ‘flat’ after awhile. Perhaps this is their rationality. It would be interesting to email these companies to discover their response…

      1. Some jurisdictions (e.g.,New Jersey) had mandated that no expiration date be beyond two years. Many companies used this nation wide even if their product will last longer rather than track multiple durations. Now that that rule has been eliminated inertia keeps the dates on the bottles.

    2. You basically have to “prove” that your product -will-not- spoil by the expiration date. That means the date quite often has -no- basis in how long the product will actually last beyond ‘at least this long’.

      There are things that are affected by light or heat even with a sealed sterile container.

      But. Just not concerned about water’s ‘expiration date’.
      1) Sterile. (Or it wouldn’t be making it to a year.)
      2) Water is chemically stable (not slowing turning into something else.)
      3) The typical water or soda bottle is foodsafe in the sense of blending-and-eating the whole thing, just NOT scary.

    3. The water doesn’t become hazardous in itself, but in some cases the bottle begins to break down–particularly the new, thin walled bottles. I wouldn’t suggest keeping “bottled” water longer than a year because of the risk of leakage.

    4. If the water that you buying got an exper. date on it , it not pure. You might want to sent it off and have it tested, for the people that test the water can tell you how long. it don,t cost 10 10 15 dollars to have it tested.

    1. If 2 liters needs 4 drops, then 20 liters needs 40 drops (a little over 3 ml)- simple proportions. 2 drops (1.5 ml) of liquid bleach for every liter of CLEAR water.

  6. Question- We have a newborn in our home and we just lost our well, new well is being installed in a couple of days. The well company is supplying us with “potable” water in large plastice containers that is sitting in our driveway. Should we be concerned with consuming’ bathing newborn’ or drinking this water in plastic containers attached to home with hose? Thank you for reply in advance. Rick

    1. If it’s potable water, that means it’s safe to drink – for anyone. The potable water being supplied to you is most likely from some municipal water supply. And they have VERY tough standards they have to meet!
      Babies, especially ones who are breast-fed, get their mother’s immunities to many common diseases, according to a number of doctors and nurses I’ve known.

    1. Treat the water for you pets as you would for yourself…

      All of my drinking water comes from a Berkey water filter for example, and my pet dog gets the same water.

  7. Great article! A LOT cheaper than paying $15 for a 1oz bottle that will only clean 30 gallons.

    Just for my personal clarification I’m hoping you can answer some of my questions on how to correctly clean and store water for a 55-gallon BPA free water drum.

    According to Sixpense’s directions above:
    1. Add 1 quart of bleach, roll all around to make sure all internal sides have been touched.
    2. Rinse. Does this mean fill 1\2 to 3\4 of the way, then empty out, then refill completely again?. Or am I just filling all the way to the top immediately until there is some good overflow?


    1. You don’t really have to swish bleach around the drum, as long as there is no dirt or anything. You are already going to be putting in water with enough bleach in it to kill all bacteria, so why rinse it with bleach to kill the bacteria beforehand?

      1. To ensure that you begin with a disinfected drum, and after having washed it and removal of any physical debris, you could choose to follow the directions in this article,

        Disinfectant Bleach-Water Ratio

        …to make a solution recommended by the World Health Organization and the CDC.

        I understand your logic that by filling it with water that already has 1 or 2ppm chlorine should be adequate, but the thing is… there’s a difference between a disinfectant formula (to treat surfaces, etc.) versus safe-to-drink formula (for the drinking water itself). I would personally feel safer having disinfected an unknown water barrel, etc., prior to filling with drinking water.

        But at the end of the day, you may be perfectly safe using your logic provided that the barrel wasn’t contaminated with something that would’ve required a stronger mixture to rid it…

    1. Sal, just a guess…
      but, maybe water the plants with untreated water..maybe the extra “content” will be good fertilizer for the plants

      wouldn’t water plants with bleach water..Bleach breaks down to salt, and salt water is not much good for plants.

  8. I have a new, blue water drum but I have filled it yet because I’m concerned about what kind of hose to use. Can I use a regular garden hose?

  9. Ken,

    thank you.

    can you recommend any type of hose, which would not be likely to degrade with the heat from the distillation? (my father in law, had a polar bear distiller, and the hose which went from the distiller to the water jug, often had to be replaced, as it would discolour and seem to deteriorate. rest of the distiller coils were stainless)


    1. If faucet water is from a municipal supply (your town water), at least here in the U.S. it will already be treated with chlorine and safe to drink. Probably 0.5 or 1.0ppm chlorine.

      Otherwise, according to this article, Bleach-Water Ratio For Drinking Water, 500 gallons would be treated with 50 teaspoons – which is 1 cup of bleach (48 teaspoons).

  10. If you store potable water in clean containers, do you have to treat it before drinking? Stored for a year or more??

  11. This might just save my life. Thank you! By far the easiest to follow article I’ve found on this.

    1. @Breeze, thanks… I’ve posted quite a number of articles on this subject throughout the blog, however I am especially happy with this one… glad it helped you.

  12. Hi, I am collecting rain water for my gardens. I have two 275 gallon totes and two 55 gallon barrels. The only thing I want is to control the algae. These will be fine for the garden as they are not being collected from a asphalt roof but algae growth has been an issue. Suggestions on amounts of bleach to use to destroy the algae?

    Thank you, Melodie

    1. @ Agri-rainwater
      Check out Ken’s article, modernsurvivalblog (dot) com/survival-kitchen/bleach-water-ratio-for-drinking-water/ ,after you have treated your water, just let it vap for a couple of days the chlorine will evaporate off quickly

      1. Thank you. I’ll assume treating for Algae is the same as sanitizing for drinking. :)

        1. @ Agri-rainwater
          Yes I would belive so. It may need several cleansing but it should work.

  13. Chlorine rapidly degrades in direct sunlight. SO, if you are unsure of measurements. Add and over estimate amount of bleach to your gallon or container and after 1 hour expose it to direct sunlight until it doesn’t smell like chlorine anymore

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