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Tech Talk:  A Very Close Look at How Water Filters Work

Tech Talk: A Very Close Look at How Water Filters Work

Eric Roy, Ph.D.  |  Scientific Founder
It seems that there is some confusion about how water filtration works, and I think it is partially due to the use of the word “filter”.  In this article, we try to clear up to the confusion with a Scanning Electron Microscope!

The word "filter" conjures up images of things like coffee filters or other things that catch particles, but a better way to think about water filtration media is as a 3-dimensional material that water flows through, a structure that better resembles a sponge.  An even better way to think about filtration media within a system is as a stack of these individual sponge-like “stages”, where each stage removes a different contaminant, until it becomes saturated.  Much like how a soaked sponge cannot mop up any more water, a saturated water filter stage doesn't "soak up" any chemicals that it was designed to remove.  This is why it is critical that any water filter used in your home has enough capacity to filter out the chemicals that you are asking it to, and that you change the cartridges before they become saturated.

The concept of "saturating a filter" is best demonstrated using  Scanning Electron Microscope (SEM) images of two different types of filtration media.   These images were collected as part of a product life cycle failure test, where we intentionally pushed the filtration system beyond its useful life.  
Water filtration media scanning electron microscopescanning electron microscope image of filtration media
The first set of images show two types of pristine filtration media before it has processed any water.  For Filtration Media Type I, the structure is 3 dimensional and  web-like, while Media Type II has a high surface area granular structure.  The two filtration media  have different microstructures because they perform different jobs in the purification system.
SEM Imgae of water filtration media
The second set of images shows SEM scans for the same two filtration media types, near the end of the cartridge's useful life.  For the Type I media, you can clearly see the particulate and colloidal contaminants trapped in the web-like structure, which is exactly how the stage is supposed to perform.  In the image of Type II Media, the previously sharp and angular looking media has formed a visible layer of contaminant "fuzz" that it has pulled from the water.   At this point in the filter's life cycle, the stages are approaching saturation, and it's time to get a new cartridge.
This final set of SEM images show what both media types look like once they've been used well beyond the useful lifetime.  If a filter cartridge is fully saturated like this, it provides absolutely no protection against target contaminants.  This is what happens when you don't replace your filter cartridge!

Pretty Neat Eh?

As always, feel free to leave water filter technology or water related questions/comments in the comments section, or send your thoughts to info@hydroviv.com.

​Have a great day!


Other Great Articles From Water Smarts Magazine:
Tap Water Chlorination:  The Good, The Bad, The Unknown
Fluoride in Municipal Tap Water:  What You Need To Know
​Disinfection Byproducts:  What You Need To Know

Should I Use A Shower Filter?

Eric Roy, Ph.D.  |  Scientific Founder
Until recently, I lived in Maine.  Born, raised, educated, job, house, dogs… all of the things…  but not in a large city.  After graduate school, I became involved with projects for work that brought me to chemical and biological weapon facilities in the DC area. After spending my first day in one of these labs, I took a shower in the hotel and found that I had a bright red irritating rash.  Given the types of chemicals I had played with that day, it was pretty terrifying. Long story short… the doctors figured out that my skin irritation was caused by being hypersensitive to chloramine in DC's tap water... not exposure to something much worse. This was an annoyance, but not something that I needed to address at the time, because my trips to the area were relatively infrequent.

About a year ago, I moved to Washington, DC, and learned that a number of my friends (also transplants) used shower water filters because they had similar issues with city water. I also learned from them that the products they used were not living up to claimed longevity and performance.  Because Hydroviv was determining our product roadmap at the time, a heavy-duty shower water filter was added to the planned product line, and we ended up finishing it first.


Best Shower Filter For ChlorineBest Shower Filter For Chloramine
As I write this, Hydroviv is in the midst of a soft launch while our core drinking water product is being buttoned up, tested, and patented, but we have some early adopters who have chosen to purchase a Hydroviv Shower Filter for a number of reasons.  Here are some of their stories, in no particular order :

  • A Creative Director for a salon in Arizona wants to avoid detrimental effects of chlorinated water on hair and to increase the effectiveness of styling products
  • A model in NYC has noticed that her hair and skin have suffered since moving to NYC, and wanted to improve both
  • A family in Maine wants to remove offensive odors from their well water 
  • Numerous people with sensitive skin (like myself) want to reduce skin irritation that occurs during showering

As always, if you have any questions, send them to info@hydroviv.com or leave a comment below.
Tech Talk:  Water Filter Stages

Tech Talk: Water Filter Stages

When people do their research on water filters, the topic of "stages" often comes up.  Water filter manufacturers try to use this spec to convince you to buy their product, but do you really know what  it means?

Simply put:  The number of “stages” refers to the number of things done to purify water within a filtration system.  Some examples of water filter stages include size exclusion filters, granulated activated carbon, ion exchange … things like that.   In theory, each water filter stage is present to improve the water’s quality.

With that said, It makes some sense that you would want the maximum number of stages to really clean up your water, right?

Sometimes Yes.  Sometimes No.  


If all stages are doing something useful… then “the more, the better”... but unnecessary or ineffective stages just slow down your filter's flow rate and drive up the price of the multi-stage water filter!

Because Hydroviv's Shower Filters are designed to handle "tough tap water"  we use 4 stages of filtration.  We use graduated size exclusion stages, and multiple stages that use advanced sorbent materials.


clogged faucet aerator

If your multi-stage water filter doesn't catch the particles, your faucet's aerator certainly will!

The purpose of  size exclusion is to catch tiny particles that would otherwise "gum up" or interfere with the sorbent materials, or could clog up your shower head or sink's aerator (see picture).  The sorbent materials are responsible for removing impurities from the water.   The end result is a highly advanced shower purification system that purifies the toughest tap water, and doesn't slow down your shower's flow rate!  

A lot of people are asking "stage-related" questions about our upcoming drinking water purification system.  Let's just say... that we can't talk about it until the patent is filed... (Can you tell that we are excited?)

If you have any questions about water filter stages (or anything else), feel free to leave a comment or email info@hydroviv.com.

Tap Water Chlorination: The good, the bad, the unknown

Eric Roy, Ph.D.  |  Scientific Founder
We get asked about tap water disinfection using a lot.  Here's the good, the bad, and what we are still learning about various aspects of chlorine in tap water.

The Good

Shortly after scientists in the 1800s demonstrated that microorganisms are responsible for many diseases, people began experimenting with ways to disinfect water.  Fast forward to 1908, Jersey City began injecting chlorine into the public tap water supply, which marked the beginning of large-scale water disinfection in the United States.  Since then, disinfection practices have become commonplace in the developed world,  and the spread of waterborne illness through public water supplies has come to a screeching halt.  This is a very good thing.

The Bad

By design, chlorine-based disinfectants (like bleach) cause damage to living things, otherwise they wouldn’t be effective.  Of course, chlorine-based compounds don't kill humans at concentrations found in tap water, but there are known side effects of consuming and showering in chlorinated water, including skin,eye & stomach irritation.  While the allowable chlorine levels set by EPA at a level low enough so they don’t cause adverse effects in the majority of people, some people (myself included) are sensitive to chlorine-based chemicals found at concentrations allowed in tap water.  

In addition to these negative “health based” side effects, there are other “nuisances” caused by chlorine in water. For example, anyone who has spent time in a chlorinated pool or hot tub knows that chlorine-based chemicals can cause hair and clothes to fade  (picture below), and a quick Google search reveals plenty of reasons for using purified water for things like watering houseplants, watering gardens, and filling fish tanks.  
Dedicated hot tub swimsuit.  You can clearly see where the waterline is!

It's safe to say that that in an ideal world, we wouldn’t need to disinfect our drinking water with chemicals  to make it safe.  However, until we find a "magic disinfection wand" that can operate economically on the municipal scale, individual households must use water purification systems if they want to remove chlorine-based chemicals from  from water used for drinking, bathing, washing food, cooking, watering, etc.  

The Unknown

Here's what we know:
  • We know that untreated water can transmit waterborne disease (e.g. dysentery, Cholera, E. coli …) 
  • We know that disinfecting water with chlorine-based chemicals greatly minimizes this risk.  
  • We know that the known side effects of chlorine-based disinfectants are minor when compared to the risk of waterborne disease. 

However, as is the case with most things, our understanding of water quality is still progressing.  A great deal of research is currently focused on a class of chemicals referred to as "disinfection byproducts."  Simply put, disinfection byproducts are the chemicals that form in water when chlorine-based disinfectants react with organic matter.  

Scientists are still studying the chemistry and toxicology of these compounds, but what we do know suggests that these chemicals may not be great for us over the long term.  

 A separate blog post on this topic is forthcoming.
Here’s additional information about the two types of chlorine-based disinfectants used in DC's water supply (as well as many other municipalities):

Chloramine

About 25% of municipalities  in the US (including Washington, DC) use chloramine (also known as combined chlorine) as the primary public water supply disinfectant. Chloramine is formed by adding ammonia to chlorinated water.  Chloramine (like chlorine) is an effective disinfectant, and it's effect is persistent in the distribution system due to its low volatility.   However, this persistence makes it so chloramine does not "go away" if you leave an unsealed container in the fridge overnight, so we have to deal with the associated taste and odor.

Chlorine:  

DC's tap water switches over to a chlorine disinfection cycle for a few weeks each spring.  This more aggressive "spring cleaning" kills any microbial buildup that may have occurred throughout the distribution system.   During these few weeks, many DC residents notice a change in their tap water's taste and odor.  Fortunately, because chlorine is more volatile than chloramine, the unpleasant taste/odor is minimized if you let a container of water sit out overnight.   

As always, feel free to comment on this post or email info@hydroviv.com to let us know what you are thinking!


Sources:  
https://www.msu.edu/~luckie/paris/290B/Pasteur.pdf
http://www.epa.gov/safewater/consumer/pdf/hist.pdf
http://www.cdc.gov/safewater/chlorination-byproducts.html
http://water.epa.gov/drink/contaminants/basicinformation/disinfectionbyproducts.cfm
https://www.dcwater.com/waterquality/faqs.cfm
https://www.dcwater.com/site_archive/news/documents/FAQ_Chlorine_Switch_2014.pdf


Other Great Articles From Water Smarts Magazine:
Fluoride in Municipal Tap Water:  What You Need to Know

Lead Contamination in Flint, MI Drinking Water:  Why it Could Happen in Your City?

Anatomy of DC's Tap Water

It may seem strange for a water purification company to write a level-headed blog post about municipal tap water, but you have to give credit where credit is due!  Municipalities are tasked with taking water from the sources like the Potomac River and making it comply with federal drinking water standards, and doing this on an enormous scale.

The Washington Aqueduct (Army Corps of Engineers)and DC Water (District of Columbia Sewer and Water Authority or DC WASA) are the two government entities that produce and distribute Washington D.C.’s tap water.  The Washington Aqueduct collects water from the Potomac River, treats it, and sells it to DC Water, and DC Water is responsible for distributing the water to homes and businesses in DC, as well as maintaining water quality standards along the way.  
"Potomacwatershedmap" by Kmusser - Own work, Elevation data from SRTM, hydrologic data from the National Hydrography Dataset, urban areas from Vector Map, all other features from the National Atlas.. Licensed under CC BY-SA 3.0 via Commons - https://commons.wikimedia.org/wiki/File:Potomacwatershedmap.png#/media/File:Potomacwatershedmap.png
The source of all Washington D.C. tap water is the Potomac River. The Washington Aqueduct transforms untreated water from the Potomac River into the water that flows from our taps.  The multi stage treatment process starts by screening out large objects (e.g. sticks & twigs), and allowing large particles (soil, silt, sand) to settle out naturally.    After this step,  aluminum sulfate is  mixed into the water, which causes small suspended particles and colloids to aggregate and settle out.  The water is then passed through a large gravity-fed filtration bed comprised of charcoal, sand, and gravel.  After this step, chlorine is added to the water, which kills microorganisms, and ammonia is added, which converts the chlorine to chloramine.  Finally, fluoride (as hexafluorosilicic acid)  and orthophosphate (a corrosion inhibitor) are added, and this water is purchased by DC WASA to distribute to their customers in The District.   

DC WASA does much more than “keeping the pipes flowing” (which with more than 1300 miles of pipe is a logistical feat on its own), they also employ a team of dedicated water quality experts, all working to ensure that water quality meets or exceeds standards set by US EPA.  This means running 24/7 compliance (tests that they are legally obligated to do)  and voluntary (above and beyond) monitoring programs throughout the city.  One interesting aspect of this voluntary program is maintaining mobile laboratories that are staffed with technicians that can be dispatched to investigate emergencies and respond to customer complaints.  

DC WASA also puts a great deal of time and effort into community engagement and public awareness. DC WASA participates in over 100 community outreach events each year to help customers understand the valuable water services they provide.  One example of these programs is the Clean Rivers Project, where DC WASA promotes best practices practices to minimize the amount of sewer overflow that is discharged into D.C.'s waterways.  In addition to managing a water education program for District students, DC WASA hosts annual town hall meetings in every ward of the city.

Throughout my career, I’ve had the opportunity to work with a number of municipalities (both large and small), and DC WASA does a very good job with information transparency.  I would encourage all residents to check out their website (www.dcwater.com) for more information, which includes things like: water quality reportsoverall strategic planand the role that residents play in maintaining water quality within their own home.
Lead Contamination in Flint, Michigan Drinking Water

Lead Contamination in Flint, Michigan Drinking Water

Eric Roy, Ph.D.  |  Scientific Founder

I wanted to take a make our readers aware of a largely unreported disaster that is underway in Flint, Michigan. The residents of Flint, MI are being poisoned by lead in their tap water because the municipality messed up... big time. In this post, I'll focus on the science behind lead contamination, the facts (as we know them) of what happened in Flint, and touch upon another incident in recent history where a similar thing happened.

​All water has impurities in it. Most impurities are harmless (e.g. dissolved oxygen, minerals), some are harmful (e.g. lead, arsenic, mercury).  

Impurities typically enter tap water in 3 ways:

1.  Some are found in the source water (e.g. naturally occurring minerals)
2.  Some are  deliberately added  as part of the treatment process (e.g. chlorine)
3.  Some are picked up along the way from the treatment facility to the tap. 


Lead is almost never found in source water at dangerous levels, and nobody deliberately adds lead to their water supply, because it's toxic.  Lead can, however, be be introduced to tap water as it flows from the treatment facility to the tap.

How is Flint’s drinking water picking up lead in transit?

It’s pretty straightforward:  Nearly all homes with plumbing installed before the 1986 use lead-containing solder to join copper pipes. Lead can also be found in residential plumbing fixtures  manufactured before 1998.   Additionally, some older homes use lead service line pipes to connect water mains to homes.   Proper water quality testing (e.g. pH, chloride, toxic metals) and corrosion control practices (e.g. monitoring chloride levels, maintaining a slightly alkaline pH, adding corrosion inhibitors) are what keep residents with older plumbing and service connections safe from lead contamination.  This is not unique to Flint.  Unfortunately, it's not always done correctly,  and residents suffer.

In Flint, as well as other places where high lead levels have leached into municipal tap water  (e.g.  Washington, DC in the early 2000’s), monitoring and corrosion control measures failed, which allowed lead to dissolve from pipes/fittings/fixtures and poison the residents.

What changed in Flint to cause the lead contamination problem?

In 2014, Flint stopped buying its tap water from Detroit (which has proper corrosion control measures in place), and began collecting their water from the Flint River as part of a plan to switch to a different water supply.  During the changeover process, the municipality failed to implement effective corrosion control measures, and the corrosive water allowed lead to leach from lead-containing plumbing.  
Because proper water quality monitoring procedures were not in place, the Lead problem was not widely discovered until recently.

​What Now?

Flint has announced that it will resume buying water from Detroit, which gets its raw water from Lake Huron and has proper monitoring and corrosion control measures in place.   This is a great first step, but it's important that Flint keeps monitoring their water for lead, because the pipes can continue to leach lead while the corrosion control measures build up the protective layer on the inside of the pipes.  The length of time this takes will depend on the degree of corrosion, and whether or not Flint's water will have "boosters" of the anti corrosion chemicals.

Until lead levels drop, residents are being urged to use a quality water filtration system that effectively removes lead.  Contrary to some of the information out on the internet... boiling water before use does NOT decrease the amount of lead.
  It is critical that Flint residents use a filter that effectively removes lead, and also changes the cartridges on a regular basis.  I would expect that the filtration capacity (in gallons) for lead would be much lower than the manufacturer claims, because the gallon capacity ratings were determined using water with much lower lead concentrations than what is currently being measured in Flint.  

Even though there is a plan moving forward, this type of incident almost certainly caused harm to some residents Flint, and the areas most affected by it were probably homes with older plumbing.  Even though lead contamination is odorless and tasteless, it has devastating effects on human health.  Since Flint began using the Flint River as a water source, numerous children have tested positive for high levels of lead in blood, and a number of schools have recently shut down water fountains due to high lead levels.   When a similar lead contamination issue occurred in Washington DC between 2001-2004, stillbirths shot up during the affected years (Edwards, 2013).   As was the case in Washington, DC, the full extent of harm likely will not be realized for several years.

*** Update June 2016:  We are getting a lot of questions from Flint residents about what to do now.  The message that we want to communicate to people in Flint is that you now have a world leader in Mark Edwards actively working with the city to help fix the problem.  There is quite literally no person on earth with more credibility than Dr. Edwards on this topic, and nobody with a better track for helping people who have been affected by this sort of disaster.  Please listen to him with open ears.  He will not lie to you.  There are a lot of far less credible people who are looking to elevate their status by saying things that will resonate with residents.  Please do not listen to them.  This problem will take longer to fix than it took to create, but understand that you now have the top expert on earth working on the problem.

Sources:​

M. Edwards. Fetal death and reduced birth rates associated with exposure to lead-contaminated drinking water. Environmental Science & Technology. Published online December 9, 2013. doi: 10.1021/es4034952.

Other Articles We Think You Might Enjoy:
Tap Water Chlorination:  The Good, The Bad, The Unknown
Fluoride in Municipal Tap Water:  What You Need To Know
​Disinfection Byproducts:  What You Need To Know