WATER: TAKING A CLOSER LOOK AT WATER

 

    

WATER EVERYWHERE—BUT IS IT SAFE TO DRINK?

 

Water is an extremely complex element. There was a time when I had a full file drawer of test data from water purification device manufacturers, all supposedly written by scientists, and all full of contradictory data. Unfortunately, each manufacturer of a water purification device had its own paid scientists to prove that its product was the best.

But I was constantly seeking the bottom line. What product is, objectively, “the best?” It wasn’t an easy answer to find. In part, this is because of water’s enormous complexity and the various components that contaminate water under different circumstances. 

Plus, to the best of my knowledge, no company, agency, or government had ever taken all the water purification devices and tested them all with control water that contained measurable amounts of known pathogens. Such a test would not only be time-consuming and expensive but would still perhaps leave many questions unanswered.

I was eager to read about a field test that Backpacker magazine had conducted of several top water purification devices. This was not a test, however, of how well the devices actually purified water, but rather how easy the devices were to use in the field. It was an interesting test, but close to meaningless from my perspective.

As far as water purification devices are concerned, I’d concluded that the Katadyne products were the best you could buy—the Cadillac of water purification devices. They are generally the most expensive, they meet all federal guidelines, and they are typically carried into the field by Red Cross emergency workers under “primitive” conditions. Yet, spending the most isn’t necessary, since nearly all water purification products meet the same federal guidelines.

In my classes where I taught (among other things) how to purify water in the wilderness and in the aftermath of an earthquake, I had to settle upon some basic advice that would be reliable in most situations.

Even though there are countless variables, on the next page is the twenty-five-cent version of water purification that I have taught my students for nearly thirty years.

That’s the outline of Water Purification 101, how to purify water in a nutshell. But there is so much more to the subject! Even some of what I thought was true in my twenty-five-cent synopsis is not!

LET’S TAKE A CLOSER LOOK AT WATER

Richard Redman teaches ecology, environmental science, chemistry, and biology at Franklin High School in the hilly Highland Park district of Los Angeles.

On an early Saturday morning, I spotted him with a dozen of his students along the foggy wet banks of Southern California’s Arroyo Seco, showing them how to test and measure water quality.

He paused to explain to me the seven measurements his students would be taking at different locations.

First, he says, the students measure the amount of dissolved oxygen in the water. He pointed out that when water gets colder, there’s more oxygen dissolved into the water. This is critical for aquatic life.

Next, they test for the presence of nitrogen, which comes naturally from dissolving rocks and minerals, and wild animal waste. The students also test for phosphates.

Redman points out that both nitrogen and phosphates can come from pollutants, but they can also come from natural sources. Both of these are fertilizers and support plant growth. “About 4 ppm [parts per million] is the normal amount of nitrogen and phosphates to be found in water in this area. But when golf courses and farming areas put these fertilizers into their soil, they will leach out into the water table and increase the concentrates of both in the water. Higher concentrates of nitrogen and phosphates cause algae blooms. As these algae grow and then die, the decomposing algae use

the dissolved oxygen in the water, and this can have a dramatic effect on the fish and other aquatic life.”

Redman’s students also do a pH test, which determines the acid-to alkaline level of the water. For example, most of the particulate matter in the air of Southern California comes from diesel vehicles. “These hydrocarbons eventually get into the water chain, typically from rain wash ing them into the ground and rivers,” says Redman. A pH test does not, however, determine a source of pollution, per se. It merely tells the acid/ alkaline level. Acid rain, for example, associated with the environment of the northeastern United States, is caused by factory emissions and vehicle emissions. He adds that, “We don’t really have acid rain in California.”

The students then test the water for turbidity. This is a visual check of the water to determine its relative clarity. High turbidity is caused by

Richard Redman records the air temperature as a part of his testing procedure.

Richard takes a water sample for a nitrogen test.

Comparing colors with a water sample to determine the level of nitrogen in the water.

microorganisms and mostly sediment in the water. His students also record water temperatures.

Determining the volume of water going downstream is also done. Redman has his students note how the nitrogen and phosphate levels in the same stream will change as the volume of water changes. “In the winter when there is typically a greater volume of water, the nitrogen and phosphates are diluted,” he explains.

Redman’s students learn about the ecology of water, and how each factor of water quality can affect another factor. “By taking seven different measurements, my students are learning that there is a whole chain of events that takes place when you do things to water. For example, trout like a maximum temperature of twenty-two degrees Celsius, or  seventy-two degrees Fahrenheit. But if the temperature of the water goes up—and this can occur naturally or as a result of run-off or water discharged from some industrial source—the dissolved oxygen count in the water goes down. Less oxygen in the water means less trout, as well as other reduced aquatic life,” says Redman.

How does all this relate to testing water for potability? Most biologists and hydrologists agree that there is no way you can determine whether or not water is safe to drink simply by looking at it.

Some of the tests that Redman teaches his students are useful for determining relative water safety. For example, if the pH test shows highly acidic water, you could have contamination from a natural or man-made cause. High levels of nitrogen could indicate runoff from a local golf course, or possibly something natural.

But for the average person backpacking in a wilderness area or in need of water after a major earthquake or tsunami, how can you decide which water to drink, and how to purify the water if needed?

Most health and wilderness experts worldwide say you should always assume that open water sources are unsafe to drink, unless you find out otherwise. This very conservative viewpoint does not mean that all open sources of water are polluted; it’s simply solid advice to avoid getting extremely sick from bad water. In most areas, water is tested by hydrologists or biologists, and if you do your homework before you enter a new wilderness area, you’ll have good information about the water’s purity.

Even when the water in an area is believed to be pure, it’s important to use common sense. Redman points out that there are many ways in which

 

 

a local area of an otherwise pure stream can be polluted. “Make sure there’s no dead animal upstream, and always be observant for sloppy campers.” In some heavily used campgrounds, lazy or ignorant campers toss garbage, baby diapers, and old food into the stream. OK, so the water’s polluted. How do we purify it?

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