© Chris Brignell | Dreamstime.com
More and more people are concerned that tap water isn’t safe so they’re choosing instead to purchase bottled water, believing it has been through “water filtration” and is therefore safer to drink. Maybe. Water filtration isn’t a cut-and-dried process, and bottled water isn’t necessarily the safest choice.
Many methods of water filtration, or water purification, are available, although at the basic level they’re either a water filter—like the faucet attachment often seen in homes—or a chemical treatment process, such as those used at the municipal level, usually in combination with a filtering process.
Municipal water supplies are treated to uphold the Safe Water Drinking Act standards that are set and monitored by the Environmental Protection Agency (EPA). The tap-water standards are even higher than the ones the EPA set for bottled water (see Is Bottled Water Safe?).
Water Filtration: What Goes Into It?
The Centers for Disease Control and Prevention (CDC) states that most municipalities use these steps in their water-filtration process:
- Coagulation and flocculation: Chemicals with a positive charge are added to the water. The positive charge neutralizes the negative charge of dirt and other dissolved particles in the water. When this occurs, the particles bind with the chemicals and form larger particles, called floc.
- Sedimentation: During sedimentation, floc settles to the bottom of the water supply, due to its weight.
- Filtration: After sedimentation, the clear water is sent through filters of varying compositions (sand, gravel, and charcoal) and pore sizes in order to remove dissolved particles, such as dust, parasites, bacteria, viruses, and chemicals.
- Disinfection: A disinfectant (for example, chlorine or chloramine) may be added in order to kill any remaining parasites, bacteria, and viruses, and to protect the water from germs when it is piped to homes and businesses.
According to ScienceDaily.com, substances removed during the water filtration process include parasites such as giardia or cryptosporidium, bacteria, algae, viruses, fungi, minerals (including toxic metals such as lead or copper), and man-made chemical pollutants.
(In my home, we sometimes smell chlorine when we run water from our faucet, which makes me wonder what was in the water we were drinking the day before. Shouldn’t they be required to announce these findings? Apparently not. According to Womenhealthmag.com, “Sometimes residents aren’t immediately told when issues are found.” That’s a little unsettling.)
You can find out what your municipal water-filtration organization may be dealing with if you go to the Environmental Working Group’s website and plug in your zip code. (Author’s note: I used my zip code and found that from 2010 to 2015, on average, seven cancer-causing contaminants and 16 other contaminants exceeded regulations. Bring on that chlorine!)
Water-Filtration Home Improvements
Even though the EPA’s guidelines for public drinking water are good, the CDC advises, we still may want to use a home water-filtration system to remove other contaminants—especially if a family member has a compromised immune system and/or we want to improve the taste of our drinking water.
You can use a point-of-entry system, which is a water-filtration system installed on the main water line coming into your house. It then filters all the water before it goes into your pipes. This may work well, but there still may be a question of pipe contaminants (not that it’s easy to determine).
“We do not currently have pipes that are 100 percent safe,” according to Healthybuildingsciences.com. “As a result, we must choose the best options available. After reviewing the research for plastic vs. copper, copper piping appears to be the system that is the easiest to control. Water filtration methods as well as new lead standards help ameliorate heavy metal toxicity risk. We do not have enough information on the dangers of plastic piping. Studies have shown alarming evidence of VOC presence, unknown contaminants in drinking water, and Assimilable Organic Compounds that can lead to deleterious bacteria. There are too many question marks to adequately enact safety precautions, and therefore plastic piping cannot be fully trusted.”
The simplest and least expensive method of water filtration is a point-of-use system—a water-filtration device placed on the faucet or under a sink (usually the kitchen sink). But you need to remember to regularly replace the filter, and always draw your drinking and cooking water from this one source. Of course, a water-treatment company will be happy to sell you both these systems.
Simple procedures such as boiling water or using a household charcoal filter are not sufficient for treating water from an unknown source, according to ScienceDaily.com. This might also be a concern with well water, which should be tested regularly. “Even natural spring water—considered safe for all practical purposes in the 1800s—must now be tested before determining what kind of treatment is needed,” says ScienceDaily.
That doesn’t mean, however, that water filtration at home is an absolute necessity if your water is coming from a municipal source.
“In general, we have an amazing system of tap water in the United States,” says Dr. Hilary Arnold Godwin, a professor in the Department of Environmental Health Sciences and Associate Dean at the UCLA Fielding School of Public Health. “The municipal districts treat the water at the plant to meet high Federal guidelines that have very strict limits on lead. There are also very stringent reporting, prevention, testing, and remediation requirements.”
HARNESSING THE SUN
Researchers from the University at Buffalo School of Engineering and Applied Sciences are using the energy from the sun to evaporate and purify water is ancient. (They aren’t the first, by the way. Aristotle reportedly described such a process more than 2,000 years ago.) By draping black, carbon-dipped paper in a triangular shape and using it to both absorb and vaporize water, the Buffalo researchers have developed a method for using sunlight to generate clean water with near-perfect efficiency.
“Our technique is able to produce drinking water at a faster pace than is theoretically calculated under natural sunlight,” says lead researcher Qiaoqiang Gan, PhD. The study was published in the May 3, 2018 issue of Advanced Science.
As Gan explains, “Usually, when solar energy is used to evaporate water, some of the energy is wasted as heat is lost to the surrounding environment. This makes the process less than 100 percent efficient. Our system has a way of drawing heat in from the surrounding environment, allowing us to achieve near-perfect efficiency.”
The low-cost technology could provide drinking water in regions where resources are scarce, or where natural disasters have struck. They’ve launched a new company, Sunny Clean Water, to bring the invention to people who need it.
“Most groups working on solar evaporation technologies are trying to develop advanced materials, such as metallic plasmonic and carbon-based nanomaterials,” Gan says. “We focused on using extremely low-cost materials and were still able to realize record-breaking performance.