Purify Our
Drinking Water? Why?
Imagine the following scenario:
You have had severe diarrhea for days and can’t figure out why. You rush to the local pharmacy only to find that they are all out of anti-diarrheal medication. This was exactly what happened in 1993 in Milwaukee, Wisconsin. Four hundred thousand people became infected and 100 people died here due to the ingestion of Cryptosporidium in their tap water.
According to the World Health Organization, 4.3 million people die every year from drinking contaminated water, mostly in underdeveloped countries where people drink water that has not been treated. More than 900,000 people become ill, and about 900 die each year in the U.S. alone from ingesting water contaminated by various microorganisms. Hence, awareness of the health effects from drinking contaminated water is of vital importance.
"Cryptosporidium" (Cryptosporidium parvum) and "Giardia" (Giardia lambia) are the two species of protozoa that have been known to be the most notorious in the nation. They are only two of the many reasons why you should drink water that has been purified. To learn more about these possibly deadly organisms and how you can protect yourself from them, please read on….
· What is Cryptosporidium?
· What is Giardia?
· How do Cryptosporidium and Giardia
get into the water supply?
· How can you protect yourself
from drinking contaminated water?
Cryptosporidium is a unicellular parasite about 3-4 microns in diameter (That’s about half the size of a red blood cell!). Therefore, it can’t been seen with the naked eye. Remarkably, Cryptosporidium is resistant to chlorine disinfection. And since it can fold to an even smaller size (as small as 1 micron), the best defense against (and probably the most effective method in killing) this possibly fatal creature is with a combination of submicron (less than 1 micron) filtration and ozone disinfection.
Cryptosporidium is a waterborne cyst that may be present in some water supplies. A cyst is an egg-like form of the parasite in its infectious stage. In this form, the protozoa can thus survive harsher conditions for longer periods of time. Once this parasite gets into the system, the cyst sheds its shell and infects the intestines.
Ingestion of water contaminated with Cryptosporidium can lead to some not-so-pleasant symptoms. For healthy individuals, it may cause diarrhea, nausea, vomiting, abdominal cramps, headaches, and low-grade fevers, lasting from 1 to 2 weeks. In people who have suppressed immune systems, including HIV/AIDS patients, cancer patients undergoing chemotherapy, infants, and the elderly, drinking water with Cryptosporidium can be life threatening.
Giardia is one of the most common causes of diarrhea in North America. Like Cryptosporidium, it is also a waterborne protozoan cyst. Unlike Cryptosporidium, Giardia, which is about 5-6 microns in diameter, can be killed by being exposed to long contact with chlorine disinfection. Filtration is also an effective method for trapping and removing this microorganism from the water supply. As with Cryptosporidium, a combination of treatments works best in keeping this parasite away from our drinking water.
Ingestion of water contaminated by Giardia in healthy individuals can cause such symptoms as severe diarrhea, nausea, anorexia, and fever. These symptoms can last from days to weeks. For those with weakened immune systems, antibiotics are necessary in order to rid the body of this parasite.
How do Cryptosporidium and Giardia get into the water supply?
The good news is that tap water coming from your faucets at home are probably not contaminated by Cryptosporidium and Giardia, since it has been through a lot of filtering and disinfection before the water actually gets to you. Ozone and filtration, when used together, remove at least 99.9% of the Giardia cysts that may be present.
The bad news is that, although rare, there have been occasions where, despite treatment, microorganisms like Cryptosporidium or Giardia make their way into the water supply. Examples of this are contamination caused by activity of animals in the watershed area of the water supply or the introduction of sewage into the water supply.
Treated water stored in open reservoirs is also subject
to contamination due to storm runoff. The infamous outbreak in Milwaukee
was due to Cryptosporidium contamination at the site of one of the city’s
main water treatment plants.
| You Tell Us
Call your local water company and ask where your water comes from, whether your area has had any recent problems with Cryptosporidium and/or Giardia contamination, and how efficient your municipal filtration is. |
How can you protect yourself from drinking contaminated water?
Here’s another scenario for you to envision: You’re hiking through the woods and you come across a serene lake with water so clear you can see through to the bottom. No nasty microorganisms can possibly inhabit a lake as beautiful as this, right?! WRONG!!!
Tempting as it may be, surface water supply sources (lakes, rivers, and reservoirs) are untreated and there is a great risk of contamination due to cysts spread through animal feces. (Yuck!) So the take-home message is to not drink water coming from these sources!
To those who have suppressed immune systems (or those of you who want to be extra safe), it is recommended by the Centers for Disease Control and the Environmental Protection Agency to either boil all tap water, invest in certain bottled water, or purchase a filter that is certified by water testing concerns to remove cysts.
Return to the beginning of the Water Quality unit.
Return to
the Cruising Chemistry homepage.