Cleaning Up Contamination with Super Chlorination

Super chlorination is a technique used to clean and disinfect water holding vessels that cannot be washed in the traditional sense. This is different from your standard disinfection, which is for cleaning the water, not the container. Super chlorination is used when reservoirs become contininated with microorganisms or have been emptied for any reason (indicating possible esposure to contamination).

Super chlorinating is simple. On a very basic level, it is just adding a large amount of chlorine to a reservoir either as a wash applied directly to the wall or as a very strong chlorine/water solution which fills the entire reservoir.
On a more specific level, it is dependant on the strength of the hypochlorite and the amount of time the chlorine is left in direct contact with the container. The stronger the chlorine the less time required. For example, if you decide to spray the walls with straight 10% sodium hypochlorite then there is almost no time required. Whereas the normal chlorine levels in most municipal drinking water systems is not enough to ever disinfect the vessel it is in. Those low levels of chlorine will only protect the water from contamination in a reservoir that is already free of contamination.

Now you might be asking how to figure out how much chlorine to add to make super chlorinated water. If you think all you need is to dump a large amount of chlorine in then I will point out that releasing large amounts of super chlorinated water into the environment is illegal in most jurisdictions. So it is necessary to calculate how much dechlorinating agent is needed. The easiest way to know the dechlorinating needs is to measure the amount of chlorine added. In order to save money or time it is best to calculate the ammount of chlorine necessary.

50 mg/L (50 ppm) of available chlorine is a great place to start. 50 mg/L left for 24 hours will meet the best pratices and standarized procedures for most jurisdictions in North America. Below is a table outlining how much chlorine you need to add for various volumes of water.


Super Chlorination Volumes at 50 mg/L (from the City of London Port Health Authority)

From this chart you can see exactly how much chlorine to add. Add the hypochlorite solution when the system is haIf full. Then fill the tank or reservoir the rest of the way with clean water. If you are disinfecting something with plumbing, like a building or a boat, then make sure the super chlorinated water makes it to each cold water faucet by flushing until you can smell chlorine (or can measure it). Do not flush the hot water faucet. all you will do is waste chlorine and hot water.

This procedure will disinfect any reservoir. Regardless of the levels of bacterial contamination, because if it doesn’t work the first time repeat the process until it does. The most likely culprit if super chlorination doesn’t work the first time is that a pipe connected to the tank wasn’t flushed completely.

Whether you have a large tank of reserve water or your rain barrels start growing dangerous microorganisms, you may need to super chlorinate one day.

Can I use a storm-water pond as a back-up source of water?

Storm-water ponds are the closest alternative source of water for many people living in urban areas. In an emergency this source of water may be all that is available to you.  Eventually any water you have stored will be consumed and the water in a storm-water pond may be the difference between life and death.  With the proper treatment your local storm-water pond can be a great backup source of drinking water.

Industrial storm-water pond (source:

Storm-water presents a unique set of challenges during treatment. Because storm-water ponds collect surface water, the water is exposed to all the contaminants on the ground in the catchment area. This includes but is not limited to pesticides and fertilizers applied to lawns, motor oil and gasoline leaking from vehicles and litter like cigarette buts. It all ends up is the storm-water pond. Those chemicals are already in storm-water ponds on a normal day. During an emergency there may be additional contamination from sewage runoff from an overloaded or broken sewage system. The water in the pond will also contain all the microorganisms like ecoli, giardia and cryptosporidium normally in surface water. Any one of these will make you very sick if you get infected with them.
Finally, there will be high levels of nitrates in storm-water ponds. Too much nitrates consumed by young children can cause blue baby syndrome.

The first step in treating water from a storm-water pond is straining. Straining the water through a cloth or loose sand filter will remove large particles (ones you could pick up with your fingers). Remove as much of the suspended particles from the water as you can. Straining the water first will extend the life of your proper water filter.

If you have a clarifying agent like aluminum sulfate, this is the best time to add it to the water.  It will make contaminants too small to be filtered become attracted to each other and become significantly larger.  Larger particles are easier to remove from the water. Let the water sit still for at least 30 minutes without disturbing it.  All the newly formed large particles (called floc) will sink to the bottom.  When you take the water from this container, make sure you leave the majority of the settled material at the bottom of the container.

Urban Storm-water pond (source:

The next step is to filter the water. Filter the water even if it looks clear, the human eye is five times too weak to detect dangerous levels of particles. Filter the water at least once through an activated carbon filter. Activated carbon is known to remove many different chemicals from water including pesticides, chlorine and fluoride. Activated carbon is not the same as charcoal. Charcoal is similar, it can remove toxins from water but it is nowhere near the efficiency of activated carbon.

The third step is oxidation. Oxidation will help with disinfection as most disinfectant chemicals are also oxidizers. Chemicals like sodium hypochlorite and potassium permanganate are both oxidizers and disinfectants. Oxidation will break down many of the remaining contaminants and inactivate many of the remaining bacteria. Keep adding the oxidizer/disinfectant till you can detect a residual after 20 minutes. The 20 minutes is the minimum you should wait for a gallon of water. Wait longer for larger volumes. This is because oxidation is a chemical reaction that isn’t instant. It needs time to complete the reaction.

The fourth step is to filter the water again. Filtering again is necessary because the disinfection/oxidation step will create some potentially carcinogenic byproducts. We filter before oxidation to minimize the amount of chlorine (or other chemical) and to limit the possibility of forming dangerous byproducts. We filter the second time to remove any byproducts that have been formed.

The final step is to boil the water.  This will help with disinfection, but the main goal of boiling at this point is to remove any volatile chemicals.  Any chemical with a boiling point lower than water will be removed after boiling.

A note about disinfection.  If all of these steps are followed there is no need for a step dedicated for disinfection.  Between the oxidation and the boiling of the water any microorganisms will be inactivated.  If you are storing the water for a long time then add some sodium hypochlorite for a residual disinfectant.  The residual disinfectant will prevent the water from becoming recontaminated before you drink it.

One additional possible step is to aerate the water.  Ponds are frequently stagnant.  Stagnant water is green with algae, it smells bad and tastes worse. After the water is made potable, transfer the water back and forth between two glasses. This adds oxygen to the water and will make the water taste better.

This may seem like a lot of work for something as small as a storm-water pond.  What I have described are the basic steps to turn the potentially toxic water in the pond into clean and safe drinking water.

Disinfection Of Water Using Ultraviolet Radiation

Ultraviolet light is a very popular method of disinfecting water.  UV radiation is part of the electromagnetic spectrum that has incredible properties for the killing of microscopic organisms.  While there are varying degrees UV resistance within microscopic organisms, not one has yet been able to develop a total resistance.  Because UV disinfection systems are not chemical or biological they have an extremely long shelf life.

The Electromagnetic Spectrum with a UV Focus (From:

There is a wide variety of ultraviolet disinfection systems that range from the size of a pen to large banks of meter long light bulbs and many options in between. UV systems tend to be very simple to install and operate and UV leaves nothing behind and there are no disinfection by-products from its application.  In fact ultraviolet radiation can break down some potentially harmful chemicals like chlorine and chloramine compounds.

Ultraviolet Lamp (from:

The limitations of UV disinfection are; distance, time, turbidity and electricity.

Proximity is critical for UV disinfection, the water needs to be very close to the UV light source. The farther away the water is the more radiation is absorbed by the water. Meaning that with increasing distance you get weakening disinfection.  Proximity becomes even more critical in hard water.  Hard water sources leave a white chalky residue of calcium carbonate which covers the UV light bulb, making the radiation emitted significantly weaker.

Time is another significant limitation of UV disinfection. The amount of time pathogens spend in the UV greatly affects whether or not the pathogen is neutralised. This is similar to how people get worse sunburns the longer they are exposed to the sun.  Time is directly related to the flow of the water, if the flow is too much, the water will not spend enough time exposed to the radiation and will not be disinfected.  Slow moving water or even static water is best.

The efficiency of UV disinfection is greatly reduced by turbidity. Turbidity physically shields the organisms from the UV light. Exactly the way a beach umbrella shades people from the sun. This is called line of sight disinfection.  There is no disinfection in the shadows when using UV radiation.

Electricity is another limitation of UV disinfection systems.  They are limited in two ways by electricity.  First by the fact that  they are quite literally light bulbs placed underwater and secondly by fluctuations in the electrical source cause fluctuations in the UV radiation field emitted from the bulbs.  Both these problems are easily overcome.  By sealing the system in clear waterproof chambers can effectively keep the system safe from the water.  Fluctuations in the electrical source can be minimized through proper system design and using fresh/charged batteries in battery powered systems.

SteriPen Portable Ultraviolet Disinfection (from

Portability is a mixed blessing with UV disinfection systems. Smaller, pen-like devices are easy to transport, but are significantly less powerful. That means they need to be used on slower moving/still water and used for longer than larger UV systems.  Another mixed blessing of ultraviolet disifection is the fact that there is no disinfection residual left in the water.  Not having a disinfection residual is great if you are drinking the water immediately, otherwise recontamination can occur very quickly after the UV lamps are shut off.  UV is not enough if you plan on storing the water for a long period of time.

Recirculating the water to be disinfected a second or third time will greatly increase the chances of proper disinfection.  Remember that disinfection whether by UV or chlorine or any other method is one of the final stages of water treatment.  Forgetting to filter the water first will make disinfection significantly more difficult.  Regardless of the size of the of the system used, ultraviolet radiation can be used to supplement any water treatment process.

PurifiCup Natural Water Purifier Product Review

When camping or hiking or even during an emergency drinking water becomes very important (water is important everyday really). You can store water easily if you don’t have to travel or evacuate, but carrying enough water if you are on foot is very difficult and very heavy. There is a need for a portable, simple, effective way to make safe drinking water.

PurifiCup is a commercially available portable water solution. I had the opportunity to test one and I put it up against some laboratory tests and my own personal judgments. It is very simple to use and is compact enough to fit into any bag and most cup holders.
This filter fits perfectly over wide mouth Nalgene bottles and screws directly onto standard water bottles. This product is very versatile and that makes it useful in a wide variety of situations.

PurifiCup Natural Water Purifier over a Nalgene Water Bottle

Some useful statistics on the PurifiCup. The cup is 10 fl oz, and it can filter 100 to 150 cups before it needs a new cartridge. It is 7.3 cm in diameter and 16 cm in height. The filter media includes ion exchange resins, activated carbon and nanoscale silver coating membrane.  The PurifiCup retails for $59.99 for the cup and filter, and replacement filters costing $13.99

Normal filters treat water by physically removing suspended materials in the water. A good physical filter removes particles as small as 0.2 microns. This will make the filter capable of removing all sizes of bacteria (but not all viruses).

The PurifiCup however isn’t a normal filter. It for one doesn’t filter below the 1.0 micron level. That is not rearly fine enough to remove all types of bacteria. This may seem like a bad thing, but the Purificup does something that no other portable water filter does (that I am aware of). The PurifiCup disinfects as it filters the water with a nano-silver membrane. Nano-silver has been shown to kill over 600 different types of bacteria.

What I wanted to know was, in a real world setting does it work? Does the product come close to meeting the claims? I tested the PurifiCup’s ability to remove turbidity, chlorine, color and its ability to kill bacteria.

PurifiCup Packed Up For Storage Or Travel

I took a sample of treated water to measure chlorine removal. The water sample I chose here is typical municipal drinking water. I also took a sample from a nearby river. This river represents a typical backup water source that could be used while hiking or in a survival situation.

There was a chlorine residual of 2.03 mg/L to start with. After filtering with the PurifiCup chlorine was reduced to 0.16 mg/L. To put it simpler, there was a 97% reduction of chlorine in the tap water. That level or chlorine reduction is amazing.

In the river sample I tested trubidity and color. Turbidity is the measure of suspended particles in the water, or the measure of the cloudiness of the water. Color is the measure of clarity of water, how close to perfectly clear is the water separate from suspended particles.
(Science Note: turbidity measures the scatter of light through the water sample and color measures the absorption of light by the sample). If you think of loose leaf tea, turbidity is the leaves in the water and color is the brown tint the water takes on. In general the lower the turbidity an the lower the color the safer the water is to drink (this is NOT always true).

The river sample started with 18.4 NTU (Nepheletic Turbidity Units) and after filtration it was 4.72 NTU. To put a little perspective to these numbers anything under 5NTU is invisible to the naked eye and at my water system I am not allowed to go over 1NTU. There was a 75% reduction in turbidity. The remaining turbidity is not terribly impressive but expected from a filter of 1.0 micron. Remember, the PurifiCup doesn’t claim to physically remove everything from the water.

Color is the final parameter I tested. Color isn’t in itself a health related property of water. A lot of color doesn’t necessarily mean the water is unsafe to drink. Removal of color however is a good indicator of the removal of many dissolved chemicals. The Color of my river sample was 128 (there are no units for color). The PurifiCup reduced that number to 81. Therefore 63% of the color was removed. This may not seem like a lot, but color is one of the most difficult things to remove from water.

Now for the parameter I was most curious about on a professional and personal level. Bacteria; does the PurifiCup actually disinfect water? I had to send this to an external environmental laboratory as I don’t have access to a biological lab. This limited the number and types of bacteria I tested. I chose to test for heterotrophic bacteria (heterotrophic plate count or HPC). These bacteria are not pathogenic, but they are resistant to many treatment processes and that makes them an excellent indicator of treatment success. I tested the HPC of the river and PurifiCup effluent.
First, bacteria tests are measured in colony forming units (cfu). A cfu is a group of bacteria that group into a visible blob (colony) of bacteria. The raw water from the river had a cfu count of 800 and the treated water had a cfu count of 500. 500 may seem like a lot, but it is a misleading number. Remember the disinfection doesn’t mean the killing of all bacteria, that’s sterilization. Disinfection is the removal or inactivation of pathogenic bacteria. Inactivation stops the ability of bacteria to reproduce and cause disease. Like I said before 500 cfu may seem like a lot. But these 500 cfu were inactivated. Remember the 1micron filter? A lot of bacteria go through the filter, but unlike the raw sample the 500 cfu didn’t grow. So while 500 cfu is a big number, they are not able to cause disease. The PurifiCup made the sample significantly safer to drink.

I highly recommend this product as part of a water purification system.  The portability and low cost of the PurifiCup makes this product a simple addition to your emergency preparations or for an avid outdoors-man’s kit.

Water Security Before, During & After Hurricanes

People often neglect to consider the security of their water supply prior to a hurricane, there are many other pressing needs for preparation, namely protection of property. Because this week is National Hurricane Preparedness Week I wanted to discuss how hurricanes can disrupt water systems and water supplies. Water security is essential when talking about hurricanes. Actions taken before the hurricane, during and after the hurricane all play a significant part in maintaining your access to clean, safe drinking water.

Hurricane Ivan: Image source

First a note on evacuations. I’m not going to tell people to stay or go when it comes to evacuating. Make that decision for yourself.

What can be done before a hurricane hits? If you are on a well, make sure your well is sealed properly. This is normal well maintenance. Your annual maintenance and inspections are your first defense against well contamination. With a hurricane the main culprit is the rain and the storm surge. Surface water contamination with bacteria, chemicals and salt can make your well very unfit to drink. Prevention through proper maintenance is the best barrier against contamination. If you are on a municipal water system, shut off the water to your house before you evacuate. This will prevent leaks and the subsequent damage from the water entering your house. It will obviously not protect you from rain/wind/flood/storm surge damage.  Also, it is a good idea to temporarily cap the connection from your house to the sewer or septic system, this will prevent overloaded waste systems back flowing into your house.  These precautions need to be done whether you bug out or not.  This is the time to store water.  When the water coming into your house is clean and drinkable.  Store as much as you can, it could be the difference between life and death.

Storm Surge Diagram: Image Source

During the hurricane, if you don’t evacuate to a safe area, you need a backup supply of water. Continue reading

What To Do When Your Backup Water Is Contaminated

Storing water in case of an emergency is a good idea. Having a reserve enables people to weather emergencies and minor service disruptions. A backup source of water is essential for emergency preparedness, three days without water will lead to death from dehydration, but serious and lifelong complications can occur well before you die from dehydration. Did you know that water sometimes needs to be retreated because clean water becomes contaminated? Water typically gets re-contaminated as people use water and they aren’t careful enough to prevent re-contamination, think about when you are washing up, hands are dirty and that leads to contamination of your stored water. Also a lot of stored water is stored for a long time “in case of emergency”. The problem with long term storage is the disinfectant residual deteriorates with time, reducing the water’s ability to prevent bacterial growth.

Preventing contamination is easier than removing contamination. Leave your stored water is a sealed and preferably airtight container. This physical barrier will stop bacteria in the environment from coming into contact with your drinking water. Next is to only open your reservoir with clean hands. Preferably washed with soap and water. It is better to pour the water you need for clean up before you make a mess. This is actually very important when you go to the bathroom, microscopic pieces of fecal matter on your hands will transfer to everything you touch, including the spigot/lid of your reservoir. Bacteria in that fecal matter will travel up the spigot into the water, it will only be a matter of time. Clean hands and routinely cleaning the exterior of your water storage tank/bottle/container/reservoir are essential to prevent contamination.

Another way to help prevent contamination is Continue reading

Non-Chlorine Pool Chemicals: Safe for Drinking Water?

When an emergency or a disaster strikes and you run out of clean drinking water, a clock starts counting down.  Three days is all that this clock has.  Three days is how long it takes a healthy adult to die of dehydration.  This journal entry is a continuation of my article on Pool Chlorine and Drinking Water. Many people with pools believe they can use this water as a back up source of drinking water,  whether or not that belief is a sound one is not always a simple answer.  While chlorine is by far the dominant disinfection agent used in pools there is a growing trend away from using chlorine.  In the first article (linked to above) I covered all the common types of pool chlorine chemicals.  In this article I will discus some of the other chemicals used in pools, and how they affect drinking water in survival situations.  I always recommend drinking the safest quality water you can get, clean untainted water that has been properly disinfected is always at the top of the list.  The advice that follows is for those situations where pool water and pool chemicals are better than tainted and untreated water.  That decision is something that everyone has to make for themselves when the emergency hits.

Salt Water Pool: (image source

Saltwater pools are the fastest growing among the alternative disinfectants. Saltwater pools may be safer to swim in, but are much more difficult to treat. If you were to drink the saltwater from a pool you would start an acceleration of the dehydration process as it takes more water to remove the salt from your body. To put it another way, it takes over one liter of water to remove one liter of saltwater. There is only one that can effectively remove salt from water is distillation. Boiling will not remove any salt at all. In fact you can boil it till all the water is gone and all the salt will remain in the pot. Distillation is the boiling of water and collection of the water vapor and steam. Then the cooling of the vapor and steam back into water into another container. Continue reading