Short answer: about 2 hours and 15 minutes if your device has two filters.
A Big Berkey holds 8.5 litres and it takes about an hour per 3.75 litres to filter the contaminants from the freshwater source you happen to be using. Of course, this isn’t the end of the story. Filtration can be affected by any number of things, so it helps to know what’s normal and what isn’t. If you want to know more about how a Berkey water filter is supposed to work, we’ll tell you more about what to expect.
The Flow Rate
There are two Black Filters in the upper chamber of a Berkey water filter, so the flow rate will be relatively slow for the water to get from the top to the bottom. As it snakes its way through, it’s the filters that catch, capture, and block many of the contaminants.
Can You Speed Up the Process?
Yes. If you add two filters to your Berkey, you can filter your water at a rate of 7.5 litres an hour. It will mean that in about an hour and 10 minutes, the entire bottom chamber should be filled. Four is the maximum number of filters that you can have, so keep this in mind when you’re filtering.
Why Is My Big Berkey Going So Slowly?
If your filtration seems to be going at a slower rate than average, it might be because of the Fluoride Filter. This device relies on dense media to stop fluoride and arsenic from getting in your drinking water. This extra step can slow down a Big Berkey.
You might also have problems if the upper chamber isn’t entirely full when you start the filtration process. It might seem counterintuitive that less water would mean slower filtration, but you’re actually forcing the filters to work harder because they’re not working at the same pace.
Ultimately, the lower part of the filter will have to work more than the top. In addition, less water decreases the gravitational pull in your Big Berkey. If you’re filling it up every time, you ensure the pressure on the filters will be even and the gravity will be enough to move the water.
Sediment and Air Bubbles
While it’s undoubtedly a little gross to see all the gunk that water filters remove, it can also be more than a little satisfying. Everything that’s built up in the filters is everything you didn’t drink. Of course, the more material that’s built up in the filters, the less space there is for the water to get through. Taking the filters out and scrubbing them down with a regular kitchen scourer can have a noticeable effect on the flow rate of your Big Berkey.
If you’re seeing air bubbles get in the way (another common bottleneck), you can also try adjusting the upper chamber or installing an anti-airlock clip. The latter option will attach to the lower chamber and add a little space for peppier filtering.
Using a Big Berkey Water Filter
From checking the lower chamber to prevent spills to filling the upper chamber up to maximum capacity, a Big Berkey water filter will take a little time to get used to. Thankfully, there are plenty of ways to troubleshoot if you’re sensing a slowdown.