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: info.evergreen.ca)

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: greenbmp.blogspot.com)

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.

Down the Drain: Persistent Chemical Contamination

What do you do with your unused and expired medications? How do you get rid of used motor oil and solvents? Your painting is done but you have some paint left over, what do you do with it?
Many people will say “I pour it down the sink or flush it down the toilet”. Even more people will lie when they say they don’t put it down the drain. Your drains are not garbage disposals for all our waste. Doctors usually recommend that expired medications get flushed down the toilet. This line of reasoning is to prevent children and pets from consuming the drugs. Maybe a doctor can expand on their reasoning more, the purpose of this article is to make a case for why using the toilet to dispose of medication is a bad idea.

Why is dumping things down the drain such a bad idea? The answer is both simple and complicated at the same time. The simple answer is that everything that goes down the drain in whole or in part survives long enough to make it back into drinking water supplies. The long answer is that contaminates survive the sewer and waste water treatment and are released back into the environment with the treated water. Then the lakes and rivers are used for drinking water. The contaminants survive the drinking water treatment and enter our drinking water. Most of these contaminants survive because the largest part of waste water treatment is biological. Therefore, anything non organic will either pass through the treatment or disrupt the treatment process or become part of the biological organisms that are there to break down waste.

In either scenario, and really all scenarios happen all the time, contamination enters the environment. In 2011, a shipment of municipal biosolids from Ottawa, Ontario, Canada was refused at the American border. The biosolids are supposed to cross the border for disposal. This shipment was refused due to radioactivity. The radioactivity came from cancer patients as the chemicals from chemotherapy pass through the body and the wastewater plant all while remaining radioactive. Radioactivity is easy to detect and in this example the chemicals came from people’s bodily waste which is supposed to go down the drain. I only mention this example because it so clearly outlines how persistent many chemicals can be.

Some chemicals mimic our hormones and disrupt our natural body systems. They have been found to cause feminization of fish and are believed to cause early onset of puberty in humans. These chemicals can come from people’s medication and from all our waste. BPA is the most famous hormone mimic. It come from the breakdown of plastics and mimics estrogen in humans. Other pharmaceuticals tend to do what they are designed to do, just now they are affecting the wrong people. Most other chemicals just cause cancer.

This contamination isn’t limited to water. Earlier I mentioned that the chemicals can enter organisms. This is especially true of plants. Plants will absorb these chemicals and then they enter the food chain. I won’t describe the food chain here, all you need to know is that the concentration increased the higher up the chain. This is called biomagnification. The apex predators get poisoned first. The main problem with biomagnification is, we are the species that eat the most other animals.

There was a study in Scanadnavia that found flame retardants in cancer patients. They traced the chemical back to the bread they had all eaten. Then back to the wheat in the field where biosolids were spread. The flame retardants were found in the municipal wastewater facility and the municipal sewers. It was traced back to one manufacturer who was putting flame retardants down the drain as part of their process. I can tell you this happens everywhere. Even if you live on a remote septic system, there is always someone upstream. Hardly seems worth it for dumping chemicals down the drain.

You might be wondering why this matters to you. Simply, it matters because we all have a part in what we put down the drain. This is true whether you live in a large metropolitan area or a remote cabin on a well and septic system. What we release into the environment comes back at us in many different directions. Detecting these chemicals is difficult because there are so many different chemicals out there that nobody can check for them all or even most of them. A lot of these chemicals pass through store bought filters. Many of these molecules are smaller than the water molecule. That means every filter is ineffective against them. To put is simply, this problem affects everyone.

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: agtuv.com)

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: halmapr.com)

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 wikipedia.org)

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.

How Does A Water Filter Work?

Whether you are building, operating or just buying a water filter, filtration is an essential part of most water treatment processes. Filtration is used in the counter top/faucet filter all the way up to municipal water treatment facilities serving tens of millions of people. Even in emergency and survival situations filtering with a shirt or other cloth is often the first thing recommended for water treatment. A shirt isn’t adequate on its own by a long shot, but it is better than un-filtered/untreated water. Used in conjunction with other water treatment steps, filtration makes the rest of the disinfection process significantly easier and cheaper.

We filter water primarily as part of the disinfection of water. Disinfection is the inactivation and removal of pathogenic organisms. Filtration is part of the removal portion of disinfection. (The other part being settling or clarification).
Filters work to physically remove contaminants from the water. They do this by passing the water through a filter media. The media presents a barrier to solids in the water. They literally collide into each other and become trapped. The media can be made of almost anything. As long as it has the ability to let water through and preventing solids from passing through. The pore size (size of space between the media) dictates the performance of a filter. The smaller the pore size the more that gets removed from the water. That sounds like smaller is better, but small pore sizes reduce the rate you can filter water and the total volume of water you can filter. It is always a trade off between ability to remove contaminants from the water and the ability to filter larger volumes of water.

Below is a diagram of pore sizes and which contaminants can be removed at a given pore size. Filters with smaller pore sizes tend to be more expensive. They require precise manufacturing techniques and maintenance.

Particle Size Diagram And How Fine A Filter Needs To Be To Remove Them

This trade off lead to the development of chemically assisted filtration. The filter media and the water itself is treated with chemicals. The water is treated with chemicals to make the particles in the water larger called floc (large groups of particles stuck together). At the same time the filter media is treated with a chemical to make the media attract and trap the particles in the water. Most chemically assisted media, has a electro-static charge opposite the one in the floc. Typically the media has a positive charge and the floc has a negative charge. Now instead of waiting for the particles to collide with the filter media, the floc is attracted onto the surface of the media (adsorbtion) and into the filter media itself (absorbtion). These types of filter media are said to be activated. Below is a diagram outlining the difference between straight filtration and chemically assisted filtration.

Direct Filtration Versus Chemically Assisted Filtration