Understanding water filters

by Pat Fox

This article was originally published in July 2018

water filters with glass

Custom Pure water has been a mainstay at PCC since 1993. Each store’s local tap water passes through Custom Pure’s water filtration system, which supplies the bulk water dispenser and produce department misters.

All of us would love a water filter that could remove all contaminants, never require service, be a compact size, super easy to install, and not cost too much. But with all filters, strengths in some areas are accompanied by limitations in other areas.

Generally speaking, the smaller a filter, the more limited it is in reducing contaminants and the more often it needs service. Larger filters, offering high purity, require more space and cost more up front. Here’s a brief comparison.

Faucet mount and pitcher filters

These are a low-cost purchase, compact and require little to no installation. However, due to their compact size, their contaminant reduction is quite limited.

Faucet mount and pitcher filters all reduce chlorine. Some can reduce copper and lead. Most do not reduce fluoride.

Their limited capacity requires frequent cartridge replacement, far more often than owners may realize, incurring costs that build up over time.

Activated carbon

These filters are terrific at reducing chlorine, organic chemicals and sediment. Some also are capable of reducing lead and parasites.

Carbon filters, however, do not take out dissolved inorganics, such as fluoride and copper; they will pass right through a carbon filter and still be in the water.

Activated carbon commonly is a component in multistage systems, including reverse osmosis, deionization and distillation.

Acid-alkaline ionizers use activated carbon as their only means of filtration. The intention in their design is only pH adjustment — not contaminant reduction. They cost far more than other systems, yet they reduce far fewer contaminants.

Reverse osmosis (R/O)

These units use membrane technology to achieve a 75–95 percent reduction of dissolved inorganics, including fluoride. They also reduce chlorine, organic chemicals, sediment and parasites.

R/O can be used on high-mineral-content water, but it produces water very slowly, requiring the use of a storage tank. For every gallon of purified water made, it produces two to five gallons of waste water!

Steam distiller

Distillers reduce 99 percent of all contaminants, creating highly purified water. They can be used effectively on a wide range of water sources.

Water is made in small batches, however, often taking 4 hours to produce one gallon of water. Distillers also use electricity and make some noise but upkeep is minimal.

Purchase cost for these can be very high.

Deionization by ion exchange

This is the primary filtration method used in the multistage system at PCC stores and in Custom Pure’s residential systems.

The deionization stage reduces the dissolved inorganics (fluoride, lead, copper, cadmium, arsenic). The activated carbon stage reduces the chlorine and disinfection byproducts. The UV stage takes care of bacteria, viruses and parasites, and the sediment filter reduces the particulates. As a complete multistage system, all contaminants are reduced. The water produced is 99 percent pure H2O.

It does all this without the need for a storage tank, electricity, or the production of waste water — and while taking up less space than comparable systems.

The bulk dispensers at PCC stores also include ozone at their output to help sanitize your bottles as you fill.

Deionization does have a limited capacity when exposed to water with high mineral content. Fortunately, Seattle-area water is very low in mineral content, making this method of filtration a perfect match in our region.

To ensure consistent water purity, the systems are monitored and serviced by Custom Pure on a weekly basis.

Custom Pure also provides residential systems designed to provide this same quality drinking water in a more compact size.

What’s in your water?

That’s the list of the most common water treatment methods for “at sink” filtration. What are your contaminants of concern?

To find out what contaminants are in your water supply, contact your water supplier and ask for the Annual Report on Drinking Water Quality. That report will give you information about your water source and the analytical results. This is a free service available to you.

If you are not yet ready to dive in and get your own filter, the bulk water dispenser at PCC remains an excellent choice for getting the most out of your water.

Your organic produce at PCC is misted with Custom Pure’s deionized water as well.

To learn more about performance capabilities of the methods listed, view the comparison chart below.

Comparison Chart

Contaminant Reduction PCC Bulk Dispenser by Custom Pure Custom Pure Home System Distiller + Activated Carbon RO + Activated Carbon Acid-Alkaline Ionizer Faucet Mount Pitcher
% of total contaminants 95-99% 95-99% 90-99% 75-95% <5% <5% <5%
TDS* Yes Yes Yes Yes No No No
Organic Chemicals** Yes Yes Yes Yes Limited Capacity Limited Capacity Limited Capacity
Chlorine Yes Yes Yes Yes Yes Yes Yes
Fluoride Yes Yes Yes Yes No No No
Lead Yes Yes Yes Yes Yes Optional Optional
Parasites Yes Yes Yes Yes Optional Optional Optional
Bacteria/Virus Yes Some models Yes Some models No No No
Time to produce 1 gal 20 sec 1 min 4-8 hours 2-6 hours 6-8 min 2 min 12 min
Service Frequency*** Weekly Yearly Per batch 1-4 times per year 1-2 times per year 4-12 times per year 14-30 times per year
Purchase Cost N/A $$$ $$$$ $$ $$$$$ $ $
Maintenance Cost N/A $$ $$ $$ $$ $$ $$
*Total Dissolved Solids: This accounts for the salts, metals, and minerals disolved in the water
**Organic chemicals: These include chlorination byproducts, agricultural runoff, pharmaceuticals
***Service frequency based on best and worst case scenarios based on 2-3 users on Seattle water conditions.

Dissolved v. undissolved contaminants

Contaminants in water are classified either as organic or inorganic, and dissolved or not dissolved (particulates).

Dissolved inorganics include lead, copper, iron, fluoride, cadmium, calcium. These also are described as Total Dissolved Solids. This group makes up about 95 percent of all the contaminants in water.

Inorganics not dissolved include particulates from iron (rust) or lead.

Dissolved organics include disinfection byproducts (trihalomethanes) and pharmaceuticals.

Undissolved organics include bacteria and viruses.

Pat Fox is co-owner of Custom Pure-the Water Store, at 1514 NE 179th St., Shoreline. Visit custompure.com for more information.

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