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How Did Hydroviv Water Filters Perform in a Duke/NC State PFAS Removal Study?

Water Nerd @ Wednesday, February 26, 2020 at 4:36 pm -0500

Analies Dyjak, M.A.  |  Eric Roy, Ph.D.

Duke University and NC State researchers recently published a study that examined the effectiveness of residential water filters against PFAS. We believe that this study is extremely important because PFAS are toxic and unregulated, which means that individuals shoulder the burden to remove them from drinking water. While we were excited to be part of this study, Hydroviv is NOT endorsed in any way by Duke University, NC State, or any of the researchers, nor did we pay any money to be part of the study.

How Effective Were Hydroviv Water Filters in Removing PFAS?

Five Hydroviv filters were tested as part of this study, four of which use currently-available active media blends. For these core formulations, the researchers tested two Under Sink Filters that connect directly to the faucet and two Refrigerator Line filters that connect to the water line that feeds the refrigerator. In all four cases, any water with PFAS present in the unfiltered samples had undetectable (below the Method Detection Limit (<MDL)) levels of PFAS after the water was filtered through a Hydroviv filter (blue text in the table below). The results here are consistent with an earlier test report that looked at PFAS removal rates. We assembled the relevant data from the more recent study for our filters in the table below. 

Duke PFAS Water Filter Study

How Did Other Common Whole House, Pitcher, and Refrigerator Filters Perform?

Unfortunately, some of the most popular pitcher, refrigerator, and whole house filters did not perform well. Alarmingly, some systems by Berkey, Aquasana, Samsung, GE, and Brita, actually had HIGHER PFAS LEVELS in the filtered water than the unfiltered sample, because of over-saturation and low quality filtration media. The red text in the table below shows detectable PFAS levels in water filtered by other major brands.Duke Water Filter Study PFAS

How Did Reverse Osmosis Water Filters Perform?

This study evaluated a number of quality water filters that use reverse osmosis (RO) technology. In each of the RO systems that were tested, any water with PFAS present in the unfiltered sample also had undetectable levels in the filtrate.

If You’re Considering Purchasing a Water Filter That Was Not Part of this Study

The advice we give people looking for a water filter that removes PFAS is to ask the manufacturer for 3rd party test data for PFAS removal (not just PFOA/PFOS) at the beginning and end of the filter’s advertised lifetime. Unfortunately, there are a lot of water filter brands (including filters that performed horribly in this study) that show test data that were conducted when the filter cartridges were fresh, and do not show PFAS test data for the end of the advertised filter life (which they base off chlorine removal). Fortunately, Hydroviv’s Under Sink and Refrigerator Line Filters were tested at month 1 and month 6 as part of this study, as well as the filters that were tested as part of the NC State/CFPUA study several years ago.


Newark Lead Crisis: Why Are the Water Filters Not Working?

Eric Roy @ Sunday, August 11, 2019 at 3:36 pm -0400

Eric Roy, Ph.D.

As a chemist, I was disappointed (but not surprised) to learn that a water filter made by Pur is having performance failures in Newark, despite being certified to remove lead. The goal of this article is to explain how water filter testing/certifications work, and to point out the most common reasons why a certified product can fail under real-world conditions

How Does Water Filter Certification Work?

Before going into the specific technical reasons why filters could have failed, it’s important to understand how and why water filter companies undergo 3rd party certifications from organizations like National Sanitation Foundation (NSF)

Any water filter company that wants to get their product "certified" must: 

  • Pay the certification agency to test that the product meets the specifications of the test protocol (more on this below).
  • Pay for project management, site visits, and listing fees to "maintain" the certification.

In addition to strengthening their marking claims, there are business reasons why water filter companies elect to pay the high cost of obtaining certifications instead of demonstrating that their product works through independent laboratories. For example, certain government entities require that products carry specific certifications to back marketing claims, and often times carrying these certifications opens up the door to large-scale government procurement (the City of Newark purchased over 35,000 of these filters for their citizens).

NSF/ANSI Standard 53 Test Protocol For Lead Removal

A lot of the people we talk to are surprised to learn that the criteria used to performance test water filters is standardized and, and may not apply to their water.

In the case of “NSF certified” filters for lead removal, the filter must reduce lead from 150 parts per billion to a certain level in room temperature water that is free of other of harmful contaminants. These tests are run at 2 different pH values (6.5 & 8.5), for the manufacturer-specified lifetime of the filter (in gallons), at a manufacturer-specified flow rate (in gallons per minute).

Water filter companies don’t get extra points for: reducing lead to undetectable levels, being able to handle higher lead concentrations, performance in the presence of other metals, having consistent performance across the entire gallon capacity, operating at higher flow rates, or performing tests at different pH values. In the eyes of certification bodies, filters either meet the performance specification or they don't.

Understanding the framework of "certification" is important in understanding why products that are certified to remove lead can fail under real-world conditions. 

Newark's Water May Not Be Well Represented by Product Testing Procedure

As we discussed earlier, “certified” filters undergo a standardized testing protocol in a controlled laboratory environment. Unfortunately, controlled laboratory studies don't always match the real-world conditions found in customer's homes.

For example, the filter's real-world performance can break down if:

  • The water’s initial lead levels are above 150 parts per billion
  • The filter was flowing at a faster flow rate than specified
  • The temperature of the water is different than the test protocol
  • If other contaminants are present in the water that consume the lead removal media

The End User May Have Used the Filter Outside of Manufacturer's Specifications

Sometimes the consumer misunderstands how to read the manufacturer's specs. For example, water filters are rated for a gallon capacity, which the manufacturers translate to an approximate filter lifetime, based on normal usage. For example, a filter that is rated to handle 100 gallons of water with 150 ppb lead might have a 3 month estimated lifetime based on "normal use." However, if the end user passes 100 gallons of water through the filter in a single day, the capacity will be saturated in a day. During the Flint lead crisis, we learned that families were using a single filter to fill up large water jugs for bathing, because they thought that the water filter's expiration was time based, not a gallon capacity. Unfortunately, this practice saturated the filter with lead much more quickly than the estimated lifetime.

Poor Manufacturing QA/QC or Changes to the Filter

It's well-understood that quality control can suffer when manufacturing is transitioned to low-cost factories. If the cartridge manufacturing facility quietyly changed anything about the filter's construction, or there was a QA/QC lapse in production, the certification agencies may not catch the performance change until the next testing cycle (which is typically every 5 years). 

The Type of Filter Distributed by Newark Allows Users to Easily Operate the Filter out of Spec

One of the negative things “end of faucet” filters is that the user can easily run hot water through the filter. Manufacturers of these products issue guidance against it in their spec sheets, but people regularly ignore the warnings so they can have filtered hot water (or so they think). What isn’t necessarily obvious to the consumer is that hot water can impact the performance of a water filter because hot water typically has much higher lead and other heavy metal levels than cold water. This is due to a number of factors (e.g. residence time in hot water tanks, temperature dependence of metal leaching). If an unexpectedly high “slug” of heavy metals flowed through the cartridge, the lead removal media will become saturated faster than the gallon rating on the package. Once the filter is saturated, it's useless. On top of this, hot water often has higher concentrations of bacterial and other particles that can “foul” a filter and negatively impact the performance. 

Takeaway Message 

Unfortunately, the filters in Newark are not performing to the levels that the customer (City and Citizens of Newark) was led to believe by the filter manufacturer. Hopefully, this event will prompt cities to independently test water filters before using public funds to purchase them.

Full Disclosure: Despite being critical of the “pay-to-play” nature of certification, Hydroviv Undersink and Refrigerator Line systems have undergone NSF certification for lead removal. You can find our NSF 53 listing here