Whole house filter installation in a San Carlos, CA  home.  


The attractive compact whole house filter installation seen above is made with standard housings using 4.5″ X  20″ cartridges. It consists of a sediment filter (left) then two carbon filters installed in parallel so that each of the carbon filters gets half of the service flow to the home.

Parallel installations are extremely advantageous.  With carbon filters like the one above targeting chloramine, doubling the capacity not only increases the effectiveness of the filter but also cuts pressure drop significantly, while more than doubling the life expectancy of the cartridges. With chloramine removal, cartridge life and flow rate are especially important.

With a theoretical maximum effective service flow rate of five gallons per minute per filter, a double filter gives you ten gallons per minute.  But,  when the total service flow is five gallons per minute, each filter is handling only 2.5 gallons per minute and the life expectancy per filter jumps from 10,000 gallons to 25,000 gallons. Similarly, service pressure drop decreases from 2.5 psi to 1 psi with the addition of the second filter.

With carbon filters, the slower the service flow rate, the more effective the filter,  the less it resists flow (and decreases pressure to the home), and the longer the carbon lasts.


Here are articles with additional information about filters of this type:

High Performance Cartridge-Style Chloramine Filters.

Chloramine Removal (our testing of our own products).

Compact Whole House Filters.

More Multi-Filter Installation Pictures.

General Installation Instructions for Compact Whole House Filters.


Dealing with the Future by Looking at the Past

by Gene Franks

A few  years ago a researcher at a local university showed that  university enrollment figures can be determined with a fair degree of accuracy by monitoring wastewater for the presence of an easily detected ingredient of birth control pills. The higher the enrollment, the more college women peeing estrogen into the sewage system.

With Covid, wastewater monitoring for the virus has been found to be not just an effective method, but the most effective method for tracking the number of cases.

In addition to  the presence of coronavirus and birth control use, wastewater testing can effectively measure the presence of  any number of environmental toxins,  diseases like ebola, tuberculosis, flu and polio,  anthrax, illegal drugs, prescription drugs, guns (by measuring gun residue), alcohol, mental illness (by testing for stress hormones), and even food and lifestyle choices.

In today’s highly charged political atmosphere it’s easy to see how wastewater monitoring might become a “rights” issue.    Sewage typically travels through publicly owned infrastructure to a treatment plant operated by a utility. Researchers and officials currently sample wastewater for public health related issues such as flu and polio without public objection. Samples are usually collected with permission of the utility, but no one asks the households being sampled if they are willing to participate.  The “founding fathers” did not mention freedom from wastewater monitoring as one of our inalienable rights, but it doesn’t take much imagination to see that looking for evidence of polio in waste water could be bitterly condemned as a plot to turn children into robots via a sinister vaccination program.


Reference Source:  The Conversation.

The EPA  says (finally) that Chromium 6 probably causes cancer

Those who saw the 2000 film Erin Brockovich will remember hexavalent chromium, also known as Chromium 6, as the chemical spreading in a plume beneath the town of Hinkley, Calif., from a disposal site run by Pacific Gas & Electric.

Those who saw the 2000 film Erin Brockovich will remember hexavalent chromium, also known as Chromium 6, as the chemical spreading in a plume beneath the town of Hinkley, Calif., from a disposal site run by Pacific Gas & Electric.


Thirty years after Erin Brockovitch. with considerable help from a Julia Roberts movie about her, brought attention to the dangers of hexavalent chromium, the EPA has said that it probably causes cancer.

“Chromium-6 is ‘likely to be carcinogenic’ if consumed in drinking water, according to an EPA draft review of the metal’s toxicity. The draft review, once finalized, will be the scientific underpinnings of EPA’s assessment of risks associated with exposure to chromium-6 and could lead to stricter EPA regulation.

Our advice:  Hexavalent chromium is a drinking water issue. There is little if any dermal uptake during bathing or otherwise using the water. See Systemic uptake of chromium in human volunteers following dermal contact with hexavalent chromium, published by the National Library of Medicine. Sensible home treatment is to treat drinking water with an undersink reverse osmosis unit, which removes hexavalent chromium handily, and to not worry about whole house treatment.

Manufacturer Changes Katalox Light’s Name to Katalyst Light

by Gene Franks

The popular iron/manganese medium that has been sold for a number of years as Katalox Light will in the future be called Katalyst Light. The German manufacturer, WatchWater, has given no explanation for the name change. One would assume a patent violation.

If you buy Katalox and it comes in a bag or box labelled Katalyst, or if you buy Katalyst and you get Katalox, not to worry. Regardless of what the bag says, it’s the same material.

While we’re revising the product name on our website,  we will also be changing the minimum backwash and maximun service flow recommendations for the filters we furnish that use Katalox/Katalyst.  The manufacturer’s original recommendations were, to be blunt, way too good to be true, but we based our recommendations on them.  The newer Katalox/Katalyst brochures have more realistic numbers and we are revising ours accordingly.

A Fool’s Errand

Sizing and setting up a backwashing filter for iron and/or manganese treatment is largely a guessing game. The more that’s known about the water being treated, the more accurate the guess can be, but in the end, it’s still a guess.  There are simply too many factors that influence backwash and service flow requirements for a “one size fits all” sizing chart to work for everyone.

Manufacturers of iron/manganese products like Katalox (Katalyst) and Filox-R pass the sizing decisions on to the user of the product by providing only vague, generalized sizing information.  The new Katalyst literature states the service flow capacity of the medium as 4 to 12 gallons per minute per square foot.  (That is, square feet of surface area of the media bed.  A 10″ diameter tank, for example, has a surface area of 0.54 square feet, while a 13″ tank has an area of about 0.92 square feet,) With Katalyst, therefore, the manufacturer is saying that if you use a 10″ tank you can treat a maximum service flow to your home of up to somewhere between 2 and 6.5 gallons per minute.  The exact service flow capacity for the individual home depends on such factors as whether you are treating iron, manganese, or a combination of the two, if there are other competing contaminants in the water (like hydrogen sulfide), the pH of the water, the oxygen content of the water, and pre-treatment provided.


With backwash rate requirement, the big unknown (to most users) is the water temperature. Cold water backwashes a filter much more efficiently than warm water, so less backwash water is needed if the water is cold. Filox’s manufacturer states the backwash requirement between 16 and 23.5 gpm per square foot, depending on the water temperature–in other words, between 8.5 (cold water) and 12.5 gpm (warm water) for a 10″ filter tank. Other important variables, like the total contaminant content, enter the equation as an educated guess. Obviously, a more vigorous  backwash is required to clean a media bed if the iron content of the treated water is 10 parts per million as opposed to one ppm. The type of tank used also matters. We use Vortech tanks for most filters and assume, based on manufacturer’s data, that Vortech tanks increase backwash efficiency by at least 20%.


With that in mind, here’s how we are revising our Katalyst (Katalox) recommendations.  The numbers are simply a guess based on the average of the high and low figures given by the manufacturer.  For example, Katalyst recommends a minimum backwash rate of  10 to 12 gpm/ft2, so we used 11 gpm/ft2.


Tank Diameter in Inches Maximum Service Flow–GPM Minimum Backwash Rate — GPM – With Vortech Mineral Tank Minimum Backwash Rate — GPM – With Standard Mineral Tank
9 4 4 5
10 5 5 6
12 6 7 9
13 7 8 10

Charts like this are not a guarantee of performance. They should be used as a starting place. If your contaminant content is high, decrease the maximum service flow accordingly. If you are planning a filtration project, we can’t guarantee a perfect outcome, but we can help you make an educated guess at sizing. The more information you can provide about the water, the better the chance of a good outcome.

Rainwater everywhere in world ‘unsafe to drink’ due to cancer chemicals

by Rob Waugh


Rainwater everywhere on Earth contains so much cancer-causing ‘forever chemicals’ that it should be classified as unsafe to drink, a new study has warned.


The chemicals – per- and polyfluoroalkyl substances (PFAS) – are man-made chemicals that spread in the atmosphere, and can now be found in rain and snow in the world’s remotest places.

The chemicals are produced by industry, and are extremely persistent in the atmosphere, the researchers warn.


As scientists have understood more about the toxicity of these chemicals, the guidelines for ‘safe’ levels have become more and more strict – meaning that rainwater would now be classified as ‘unsafe’.


Lead author Professor Ian Cousins, of Stockholm University, said, “There has been an astounding decline in guideline values for PFAS in drinking water in the last 20 years.

“For example, the drinking water guideline value for one well known substance in the PFAS class, namely the cancer-causing perfluorooctanoic acid (PFOA), has declined by 37.5 million times in the U.S.”

“Based on the latest US guidelines for PFOA in drinking water, rainwater everywhere would be judged unsafe to drink.

“Although in the industrial world we don’t often drink rainwater, many people around the world expect it to be safe to drink and it supplies many of our drinking water sources.”

The Stockholm University team measured the atmospheric presence of PFAS for the past decade.


Levels of some harmful PFAS in the atmosphere are not declining, despite their phase out by the major manufacturer, 3M, already two decades ago.

PFAS are known to be highly persistent, but their continued presence in the atmosphere is also due to natural processes that continually cycle PFAS back to the atmosphere from the surface environment.

Professor Martin Scheringer, a co-author of the study based at ETH Zurich in Switzerland,

“The extreme persistence and continual global cycling of certain PFAS will lead to the continued exceedance of the above-mentioned guidelines.

“So now, due to the global spread of PFAS, environmental media everywhere will exceed environmental quality guidelines designed to protect human health and we can do very little to reduce the PFAS contamination.

“In other words, it makes sense to define a planetary boundary specifically for PFAS and, as we conclude in the paper, this boundary has now been exceeded.”


PFAS is a collective name for per- and polyfluorinated alkyl substances or highly fluorinated substances that have a similar chemical structure.

All PFAS are either extremely persistent in the environment or break down into extremely persistent PFAS, which has earned them the nickname “forever chemicals.”

PFAS have been associated with a wide range of serious health harms, including cancer, learning and behavioural problems in children, infertility and pregnancy complications, increased cholesterol, and immune system problems.

Dr Jane Muncke, managing director of the Food Packaging Forum Foundation in Zürich, Switzerland, who was not involved in the research, said: “It cannot be that some few benefit economically while polluting the drinking water for millions of others, and causing serious health problems.

“The vast amounts that it will cost to reduce PFAS in drinking water to levels that are safe based on current scientific understanding need to be paid by the industry producing and using these toxic chemicals. The time to act is now.”

Source: Yahoo News.

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Countertop Water Filters Are Better Than Ever


Model 77.  After 30 years, still “the world’s greatest $77 water filter,” and now better than ever.


Change in kitchen sinks and countertops have both helped and hurt countertop water filters.

Countertop filters get their water by attaching to the sink faucet. The rise in popularity of sink faucets with pull-out sprayers has reduced the use of countertop units because the deeply recessed aerator in the pull-out sprayers makes it impossible to attach the filter’s diverter valve.

The rise in popularity of granite countertops, on the other hand, has added to the popularity of countertop filters because drilling a hole in the granite countertop for the faucet of an undersink filter or reverse osmosis unit can be difficult and expensive.

Though countertop filters have only a small share of the drinking water filter market,  countertop units are alive and well and probably here to stay. Their low cost, portability, ease of installation, and long-term reliability make them valuable and popular water treatment devices.

Standard-sized countertop filters, like the one pictured above, are better than ever because the standard 9.75″ X 2.5″ filter cartridges that fit them are so much better than they used to be. Modern cartridges not only have unbelievably long chlorine capacity but many can treat such difficult contaminants as PFAS,  VOCs,  lead, chloramine, and the full range of organic chemicals.


A double countertop has twice the capacity of a single unit. Using a double filter also allows treatment of difficult items like fluoride, arsenic, nitrates, and even bacteria while still  providing top-notch all around chemical performance and excellent taste and odor improvement.

More about countertop water filters.

MatriKX Cartridges Are Now Certified for Reduction of PFAS



The MatriKX Chloraguard drinking water cartridge pictured above is now rated to treat an incredible 45,000 gallons of chlorine, 4,000 gallons of chloramine, 3,500 gallons of PFAS, and 750 gallons of VOC.


When we started building our Model 77 Countertop Filter around 1990, the standard cartridge for the unit was the MatriK KX-1.  The KX-1 was a really good cartridge. It was a bituminous coal based carbon block that boasted 20,000 gallons of chlorine capacity. The manufacturer’s advertising line called it “The Chlorine Guzzler.” We used the KX-1 in the Model 77 countertop as well as our Black and White series undersink filters and RO units. Over the 30 plus yeas that we’ve been using the cartridge it has been reformulated and renamed a few times. It is now called CTO Plus.

The CTO Plus is now made with coconut shell carbon. The chlorine capacity has gone up to 30,000 gallons (not that you would every use it that long) and it now has a 750 gallon capacity rating for VOC reduction. VOCs, “volatile organics,” are a challenge, and 750 gallons is something to brag about. Chloramines are also a challenge. The new spec sheet for the cartridge now shows its certification at 2.000 gallons capacity for chloramines, as well as 3,500 for the difficult “forever chemicals” known as PFAS.

All four of the basic MatriKX cartridges now have certification for chloramine reduction and all but the standard CTO make claims for VOC reduction. All four are now made with coconut shell carbon and all are manufactured with the latest and most advanced technology. (This is important. Not all carbon block filters are created equal. Much of their effectiveness depends on the processing of the carbon and the binders used.)

The manufacturer’s fact sheets for the four basic cartridges can be found on our website.  Links are below. Performance data is given for the four basic standard filter sizes–from drinking water to whole house.

PB1 – Lead/Cyst Removal Carbon Block.

CTO Carbon Block

CTO Plus Carbon Block

Chloraguard Carbon Block

Below is a comparative breakdown of the four basic styles in the drinking water size only.  The summary tells you that you do not need a six stage filtration unit to get superb performance.  To illustrate, our standard double undersink filter, which uses the MatriKX PB-1 and the MatriKX CTO Plus,  provides 60,000 gallons of treatment of chlorine,  4,000 gallons of chloramine, 6,500 gallons of PFAS, 1,250 gallons of VOC, 3,750 of lead, plus protection against cysts.  It is generally recognized that a carbon filter that removes VOCs (which are very difficult to treat) also offers protection against the literally thousands of chemicals and pharmaceutical products for which no testing is done.

MatriKX Summary Sheet – 9.75” X 2.75” Cartridges

MatriKX Cartridge

Performance Summary

MatriKX PB1

Coconut Shell Carbon Block. Nominal 0.5 Micron

PWP Part FC004

Chlorine Removal : 30.000 gals. @ 1 gpm

Chloramine Removal: 2,000 gals. @ 0.5 gpm

PFAS Removal: 3,000 gals. @ 0.5 gpm

VOC Removal: 500 gals. @ 0.5 gpm

Lead Removal: 3,750 gals. @ 0,75 gpm

Cyst Removal:Yes, for life of cartridge


Coconut Shell Carbon Block. Nominal 5 Micron

PWP Part FC003

Chlorine Removal : 12,000 gals. @ 1 gpm

Chloramine Removal: 1,000 gals. @ 0.5 gpm

PFAS Removal: 3,250 gals. @ 0.5 gpm

VOC Removal: Not Rated

Lead Removal: No.

Cyst Removal: No.


Coconut Shell Carbon Block. Nominal 1 Micron

PWP Part FC001

Chlorine Removal :30,000 gals. @ 1 gpm

Chloramine Removal: 2,000 gals. @ 0.5 gpm

PFAS Removal: 3,500 gals. @ 0.5 gpm

VOC Removal: 750 gals. @ 0.5 gpm

Lead Removal: No

Cyst Removal: No

MatrikX Chloraguard

Coconut Shell Carbon Block. Nominal 1 micron

PWP Part FC040

Chlorine Removal : 45,000 gals. @ 1 gpm

Chloramine Removal: 4,000 gals. @ 0.5 gpm

PFAS Removal: 3,500 gals. @ 0.5 gpm

VOC Removal: 750 gals. @ 0.5 gpm

Lead Removal: No

Cyst Removal: No



EPA Standards for PFAS Are Just Around Some Far-Distant Corner

The Environmental Protection Agency announced interim health advisories for four perfluoroalkyl substances (PFAS) that are substantially lower than the advisory levels issued by the agency in 2016.  The EPA’s  heath advisory from 2016 called for no more than 70 parts per trillion for the combined concentrations of PFOA and PFOS.  A Health Advisory, or HA,  is miles of political maneuvering away from an enforcable standard that would actually require municipal water providers to reduce PFAS to a specified level. 

PFAS are a group of manufactured chemicals that have been used in industry and consumer products since the 1940s. There are thousands of different PFAS, some of which have been more widely used and studied than others. One common concern is that PFAS generally break down very slowly, meaning that concentrations can accumulate in people, animals, and the environment over time. They are often referred to as “forever chemicals.”  PFAS ingestion has been implicated in human health issues from birth defects to cancer.

The updated EPA  Health Advisory for PFOA is 0.004 ppt.  That’s parts per trillion. For PFOS it’s 0.02 ppt.

Although it may take years of political wrangling before EPA enforceable standards are finally set for these “forever chemicals,” the PFAS issue is not as complicated for individuals. Here’s what you should know.

First, PFAS, like arsenic, fluoride, lead, nitrates, and some other significant water issues,  are almost entirely an ingestion issue. There is general agreement that routine household use of PFAS-contaminated water, including bathing, does not pose a health risk.  It is a drinking water problem.

Removing PFAS from drinking water is not hard at all. Point of use reverse osmosis units remove PFAS handily. Likewise, good quality carbon drinking water filters.

Whole home treatment of PFAS is more difficult, but high quality carbon block filters with regular cartridge change can provide PFAS-free water for the whole home.







Understanding VOCs

Posted April 8th, 2022

VOCs For Non-Scientists: Understanding, Detecting, Removing

This is a straightforward explanation of the highly problematic group of water contaminants known as VOCs. The article is from the Calgon Carbon Corporation, a leading supplier of water treatment media.


Volatile organic compounds (VOCs) are a large class of substances that may be found in various water sources. Many water quality managers and operators at water treatment plants (WTPs) know which substances are considered VOCs but not all understand the chemistry behind the designation. What follows is a straightforward guide to understanding VOCs, specifically, what qualifies a compound as a VOC, how to detect them, and how to treat and remove them from the water system.

What Is A VOC?

As the name implies, a VOC is defined primarily by two things. The first is that the chemical is volatile, which means that it easily changes state from liquid to gas with a relatively small amount of energy. Most VOCs have a comparatively low molecular weight, which is one of the reasons for this volatility. The other key defining factor is that it is organic, meaning the molecule is composed primarily of carbon atoms.

Most VOCs are manmade products, although a few, such as acetone, are also naturally occurring. That means nearly all VOCs end up in the water supply via industrial processes, chemical spills, or other human activity.

Nearly all VOCs are manmade.

Half come from industrial processes, 45% from motor vehicles, and 5% from consumer solvents.

VOCs in water are analyzed for using the U.S. EPA method 524.2. This process involves purging potential contaminants from a water sample using inert gas then desorbing them into a capillary gas chromatography column connected to a mass spectrometer.


Federally regulated VOCs are listed under the Safe Drinking Water Act (SDWA). Of course, each individual state may have its own list of regulated VOCs beyond those in the SDWA.


VOC Levels

For regulated VOCs, the EPA and state agencies set two levels for each chemical: a maximum contaminant level (MCL) and a maximum contaminant level goal (MCLG). The MCL is the largest permissible concentration of the chemical in water, while the MCLG is the concentration at which there is no known or expected health risk.

VOC Types And Properties

Not all VOCs behave the same. There are three sub-classifications of VOCs based on their boiling points:

  1. VVOCs (very volatile organic compounds). With boiling points of <0°C to 50-100°C, many of these exist solely in a gaseous state. Examples include butane, propane, and trichloromethane.
  2. VOCs (volatile organic compounds). Although the term VOC is often used to describe chemicals from all three subcategories, technically it applies only to those with boiling points in the 50-100°C to 240-260°C range. Some examples are ethanol, acetone, and vinyl chloride.
  3. SVOCs (semi-volatile organic compounds). The least volatile subclass is defined by boiling points from 240-260°C to 380-400°C.  Phthalates, many pesticides (including DDT), and nitrobenzene are some such examples.

VOCs can be further categorized as either hydrophobic (repel water) or hydrophilic (attract water). Hydrophobic VOCs (e.g., benzene) usually have smaller molecular weights and do not dissolve easily in water, which makes them relatively easier to move to a gaseous state. By contrast, hydrophilic VOCs (e.g., acetone) tend to have higher molecular weights and are more easily dissolved in water, which makes them relatively harder to move into a gaseous state.


Removing VOCs From Water

There are two primary methods for removing VOCs from source water.

Air Stripping. The process of forcing air through water works well on VOCs with lower boiling points (especially VVOCs) and/or those that are hydrophobic. This includes chemicals such as vinyl chloride, methyl chloride, chlorofluorocarbons, and methane.

Activated Carbon. Higher-molecular-weight VOCs won’t be as responsive to air stripping. For these chemicals, a granular activated carbon (GAC) filter is a more effective solution. The activated carbon can adsorb most VOCs, including those that are more difficult to remove via air stripping. Because VOCs diffuse quickly through the carbon bed, however, it is important to ensure the carbon has a high iodine number. Usually, about 1,000 to 1,100 is ideal to reduce the number of changeouts.

Establishing A Buffer For VOCs

It’s rare for water treatment plants to discover new VOCs in their source water. Most water systems are well established, and the challenge is less about tackling a previously unencountered chemistry but rather struggling to meet established and new MCLs.

That said, chemical spills can happen anywhere. For example, a city that pulls from a riverway with heavy boat traffic is always susceptible to some type of spill, as anything that is on a boat can end up in the water. Even chemical spills on land, such as a tipped gas tanker, can result in VOCs in groundwater. A GAC system that is in place for everyday VOCs will act as a buffer, ready to adsorb new contaminants should they enter the source water.

Source: Calgon Carbon Corporation

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Posted March 15th, 2022

Mercury in Water



Mercury is a neurotoxin that harms the lungs, the kidneys, the immune system, the heart and the brain.  The young and the unborn  are most at risk and severe developmental problems can result from mercury poisoning. Mercury can be a water contaminant, but eating poisoned fish is the main cause of mercury poisoning in humans.

For mercury contaminated water, the EPA-recommended treatments that are available to residential users are activated carbon filtration, reverse osmosis, and distillation. Mercury exists as an organic contaminant (that’s what poisons fish) and an inorganic pollutant.  It is the inorganic form that contaminates drinking water.

According to a 2012 report from the NRDC (Natural Resources Defense Council), over half of the Great Lakes region’s noxious mercury pollution can be attributed to the 25 worst coal-fired power plants in the Great Lakes area.   Nationwide, over half of mercury pollution comes from coal-fired power plants.


Reference: Your Bass Guy