Solid Carbon Block vs. Granular Carbon

Which material is better for water filters? 

Water sources can contain some contaminants that affect your long term health, the taste & smell of the water and other microbiological contaminants that can actually make consumers sick shortly after drinking, for example virus, bacteria, and cysts (giardia & cryptosporidium). Fortunately, there are water filtration products that remove many of the impurities from water. These filters often use carbon. Two dominant carbon filter choices are solid carbon blocks and granular activated carbon filters.

Filter Design

Granular activated carbon filters have loose granules of carbon that look like black grains of sand. Solid block carbon filters have blocks of compressed activated carbon that are formed with the combination of heat and pressure. Both filters are made from carbon that’s ground into small particulate sizes. Solid carbon blocks are ground even further into a fine mesh 7 to 19 times smaller than the granular activated carbon filters.

Less Contact Time

Flow channels also develop between the granules in the granular activated carbon filters, leading to less effective filtration as there’s less contact between the water and carbon. Solid carbon blocks are much tighter and won’t even let through microbial cysts like giardia and cryptosporidium. However, solid carbon block filters are so tight that they can often get plugged up with matter, forcing owners to replace them on a more regular basis. This is why when you are using a Brita water pitcher filter (granular carbon), the filter will keep going and going long after it has stopped removing any water contaminants. Why bother? 

Woder Granular Carbon Filter (Left) vs. Epic Smart Shield Carbon Block (Right)

Cross Section of Epic Smart Shield Solid Carbon Block Filter

Better Filtration

The solid carbon block filters like the one used in the Epic Smart Shield remove more contaminants than the granular activated carbon filters due to the larger surface area and the tighter filters, this is why Epic Water Filters has standardized on the solid carbon block design for our water pitchers and our under the sink water filter. Granular activated carbon filters do not do enough to reduce contaminants and they are cheap to make. They are truly not "Epic" so that is why we have passed on this design and let our competitors like Woder, Brita, Pur, and Invigorated Water use these loose packed carbon filters for sub-par contaminant removal.

With solid carbon block filters the contaminants are in contact with more carbon for a longer period and therefore have more time to remove stubborn contaminants like lead (Epic Pure Pitcher 99.9% removal), fluoride (Epic Pure Pitcher 97.8% removal), and PFCs (Epic Pure Pitcher 99.8% removal). Carbon blocks can remove chlorine more effectively, eliminate undesirable odors, and removal endocrine disruptors like volatile organic compounds. The granular activated carbon particles move around, so the filter does not have as much uniformity throughout, unlike the solid carbon blocks.

Solid carbon blocks have millions and millions of different sized pores that cause the water to take a long slow path to get through the filter, increasing the contact time that the contaminated water has with the carbon. During this contact time is when contaminants adhere to the carbon and are removed from water. This happens during a process called adsorption, the other filtration method that carbon blocks use is called depth filtration where the thickness of the filter comes into play to help remove contaminants as they have to pass through this carbon walls. 

Block vs Granulated

The granular activated carbon filters are cheap and simple to make which is why most water filtration companies (Brita & Woder) choose this method for manufacturing. Solid carbon block carbon filters on the other hand take longer to make and are more expensive but with this expense, you get better contaminant removal because the water has to take a tortured path before it reaches your family's lips.