There are a lot of variables in this topic, so I thought we could get into a bit more detail in addressing some of those factors relating to the lifespan of the Berkey filters.
What is the lifespan of a Berkey filter?
The first thing to note is that the “lifespan” of the Berkey filters, as designated by the manufacturer, is not necessarily the exact length of time that your Berkey filter will function optimally for you. It is instead the amount of time after which you ought to replace your filters if you are concerned about the integrity of the filters and the cleanliness of the water you are drinking.
Functionally, the filters may never entirely stop allowing at least some water to pass through, but eventually (after the lifespan is up) the water that does go through and comes out of the filter cannot be guaranteed to meet the standards of cleanliness than you can depend on. This is because after a certain amount of time the filtration medium inside the filter gets used up (more on that in a minute). This is why it’s good to keep track of when you began using your system and approximately how much water you use per day, so that you can calculate when the filters should be replaced.
Functional vs. definite
How long the filters will function is basically an entirely separate matter from the definite lifespan. A lot of times they’ll still continue to allow water to pass through long after the lifespan is up, especially in the case of the ceramic filters, but you don’t want to drink this water for the reason mentioned above.
Other times, usually in the case of the Black Berkey purifiers, the flow rate may gradually slow down to the point where you’ll want to replace them before the 6,000 gallon lifespan is up. When this happens, it simply indicates that for different reasons, your water source has a higher content of contaminants or micro-particles that the purifier has been removing over the course of its life, and the micro-pores inside are getting completely filled up and clogged. In other words, the purifier has been doing its job!
Increasing flow rate and maximizing functional life of filters
If you prefer a faster flow rate and want to extend the life of your primary filters (the ceramic or the Black Berkey), you can add more filters to your system as long as there are extra filter holes in your canister. When doing your calculations for the lifespan, simply double the estimate for every pair of filters you add in. It’s a matter of the amount of water that’s going through them, not a matter of time. So if you have 4 Black Berkeys in your system, the lifespan would go up to 12,000 gallons of water. With 4 ceramics, the lifespan would be 2,000 gallons.
That is also the case for the PF-2 white fluoride/arsenic filters that pair specifically with the Black Berkey primary filters. The filtration medium inside each filter is being used up more slowly the more filters you have, so if you have 4 PF-2s in the system they will last for approximately 2,000 gallons of water. A noticeably slower flow rate generally is an indicator that they have reached the end of their lifespan, but do replace them after their lifespan is up, even if the flow rate hasn’t slowed down.
The PF-4 fluoride/arsenic filters (used only with the ceramic primary filters) are the only exception as far as lifespan goes…with these in particular, they are time-sensitive, meaning that once they are exposed to water, the clock starts ticking for their lifespan. A pair lasts 500 gallons of water or 6 months, whichever comes first. This is due to the fact that after 6 months of use, there’s a possibility for bacterial growth to occur.
If the fluoride/arsenic filters start slowing down before their lifespan is up (particularly in the case of the PF-2s, since their lifespan is longer), you can try removing them from your system and flushing them on both ends with water, using a priming donut to create a seal between a water faucet and the filter opening.
The ceramic filters will likely slow down periodically before they reach the end of their lifespan, but scrubbing off the outer layer with an all purpose scouring pad under running water usually helps restore a good flow rate. The carbon medium inside the ceramic shell will eventually get used up, though, so it’s important to still pay attention to the estimated lifespan.
The same scrubbing procedure, along with re-priming, can be done with the Black Berkey purifiers to help extend their functional life if they start slowing down.
Understanding the carbon adsorption factor
So how does the medium in the filters get “used-up” or exhausted after a certain amount of time? One of the main facets of how these filters clean water is through adsorption – impurities adhering to the carbon filtration medium. The ceramic filters have a loose carbon medium inside the outer ceramic shell; the Black Berkey purifiers are composed of a proprietary medium containing carbon. Adsorption is different than absorption, which is where one substance soaks into another substance. The adsorption qualities of the filter become exhausted after a certain amount of usage when the adsorbent matter (the carbon) becomes covered in the film of the molecules that it has drawn out of the water to stick to itself. This means that even if some water is still able to pass through the micro-pores (another facet of the filtration method), some impurities could be getting through due to the adsorption qualities failing over time.
As you can see, at the end of the lifespan of a filter, it still might be filtering out some toxins, but it very likely isn’t filtering out the quantity that it was in the beginning. At that point, the integrity of the purifying or filtering capabilities is compromised and not reliable anymore.
I hope this information has been useful to you! Let me know your questions and comments down below; I’d love to hear what you’re thinking.