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Discussion Starter · #1 ·
After some poking around, I am convinced that the black Berkey filters are the only way to go when it comes to water purification. These filters, though expensive, are the only ones I have seen that will actually purify the water instead of just filtering it. This means they remove virtually all of the pathogens (like bacteria) and make secondary treatment unnecessary.

As I see it, the basic Berkey system has an irritating design flaw: the bottom of the filter does most of the work. Once the water level drops, the top isn't used at all. This reduces flow rates and shortens the life of the filter. There has to be a better way, and there is...



The picture on the left shows the typical setup. As you can see, the top of the filter isn't doing much.

But if you make a setup as shown on the right, you will make full use of the filter almost all the time. I would size the lower extension so that it holds about 1 quart plus the filter. If you have 4 gallons in the top part (16 quarts) all but the last quart will use 100% of the filter. Since 15/16 = .9375, this means that the whole filter will be used at least 94% of the time.

There are 2 benefits from doing it this way; the water in the extension will be pressurized a little the weight of the water above and pass through the filter faster, and since you are using the whole filter, it should last longer. I would conservatively estimate that the flow rate and filter life will both double. This means that a single filter modified unit would give you the same performance as a 2 filter standard unit. You would basically be cutting the filter costs in half.

There are also 2 disadvantages: the whole thing would be a little taller, and it would cost more time and effort to make. Standard Berkey units are kind of tall and thin. If you used wider, shorter containers (like a 20 quart stock pot), the overall height of the modified unit wouldn't be that much taller than a standard Berkey unit. The sdditional cost and time needed to build a modified unit would be offset by the savings in filters.

There are several ways you could actually make this thing. It could be all stainless and either TIG welded or silver soldered. It could be all plastic and be epoxied together. It could be a combination of materials, etc. etc, etc.
 

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Great idea! I really do hate the fact that only a tiny part of the filters do the majority of the work... I reduced the # of filters I use to help offset this, but then the flow rate is sooooo slow.
 

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I had this exact same question when I bought our Berkey. I even called their customer support number and after being passed around to a few different people, I finally found someone that "seemed" to have some engineering knowledge and he explained it something like this:

The way the filters are designed, the water does not pass through the filter because of the weight of the water in the reservoir, rather the filter material absorbs the water from the reservoir and disperses it evenly throughout the filter material. When the filter material is fully saturated and cannot hold anymore, the excess water begins to condense as droplets on the inside hole in the filter and drip through to clean water container. So, even if the top of the filter is not submerged, it is still "wicking" the water up and performing the filtering operation. He explained it as using a similar principle to how a kerosene lamp wick will absorb kerosene from a bottom reservoir and move the oil to the top of the wick where it is burned. It is also why the Berkey filters have to be "charged" with water before you put them in the device or they will not work.

Note: This explanation could be complete B.S. as I have not seen the engineering docs on the filters themselves. But at the time, it satisfied me enough to shell out the $$$ to buy one. :smile: But, the little bit of testing we have done with the device does appear to support the explanation though. The tops of the filters do stay completely wet even when the water level in the reservoir is only an inch or two deep.
 

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Discussion Starter · #4 ·
I can see all that, good to know. I was kinda wondering if some sort of capillary action was going on there. If the top of your filter stays wet, it kinda confirms that.

If those filters are at all porous, increased pressure would improve flow. I saw a YouTube by a guy who used a small pump to pressurize his system to only 2 psi and the flow increased a lot. He was only using ceramic filters though, so I dunno if that would help with the black Berkey ones.

Screw it, I'm gonna order a set of them and play around a little. I have been resisting this because I want to move soon and don't need a bunch of new stuff to be packed and whatnot, but water is a primary need and I don't want to get caught short.

Thanks for the info Inor, I'll keep ya posted. :)
 
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Discussion Starter · #5 ·
OK, this project is officially cancelled. LOL

I was going to use clear acrylic tubing for my down extension, but it's like $14 a foot with a 6 foot minimum. By the time all was said and done, the one I was gonna make wouldn't have been much cheaper and no guarantees it would work better anyway.

So I ordered a Big Berkey and 2 LifeStraws.

Once I get into my new location (which might be 6 months from now the way it's going) and set up a shop again, I'll get back into mad scientist mode and start experimenting. I also want to play around with making my own batteries. Oh yes, much mad scientist experimenting!

Thanks again Inor, I have the feeling you saved me a lot of trouble for nothing.
 

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OK, this project is officially cancelled. LOL

I was going to use clear acrylic tubing for my down extension, but it's like $14 a foot with a 6 foot minimum. By the time all was said and done, the one I was gonna make wouldn't have been much cheaper and no guarantees it would work better anyway.

So I ordered a Big Berkey and 2 LifeStraws.

Once I get into my new location (which might be 6 months from now the way it's going) and set up a shop again, I'll get back into mad scientist mode and start experimenting. I also want to play around with making my own batteries. Oh yes, much mad scientist experimenting!

Thanks again Inor, I have the feeling you saved me a lot of trouble for nothing.
If you just whacking together a quick prototype for testing, could you just use PVC? It is cheap, easy to weld with the purple juice, and available everywhere. - Now you have me wondering. :?
 

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Discussion Starter · #8 ·
Now you have me wondering again. If the main action of the filter takes place due to this wicking effect, why do you have to prime the filters? Capillary action should work even if the filters were completely dry to start.

The filters have to be at least a little porous. Being in direct contact with slightly pressurized water would almost certainly make them work faster. If the top was exposed to pressurized air, I am guessing the air would escape through the filter, releasing the pressure. Air, after all, is thinner than water.

But my main concern isn't about speed. I will probably fill it the night before I need it, then replace water as I use it. If you do this, you will always have clean water available.

If the entire filter is being used due to the wicking action, there seems little reason to do anything, even if it does take longer that way.

Because the pores are so small, I would imagine the filters will stay wet a long time, even with no water in the system. The air in the container would be near saturation, so the moisture on the surface can't evaporate unless the temperature increases or drier air is introduced. Once the surface of the filter does dry through evaporation, water would migrate from inside the filter seeking equilibrium. With the lid on, this would take a long time.

What I'm saying here is that I can't think of any way to test whether the whole filter is actually being used or not.

I should have my system by Friday. Maybe once I get my hands on it I will figure out a way to see if the whole filter is being used or not.

Meanwhile, I am thinking about how I can make batteries that will run on tap water. :p
 

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Meanwhile, I am thinking about how I can make batteries that will run on tap water. :p
That's easy...

Take a big glass of tap water up to Walgreen's. Throw it on the clerk. While she is freaking out about you throwing tap water on her, grab a bunch of batteries off the shelf and run like hell! :p
 

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Discussion Starter · #10 ·
I'm thinking more along the lines of taking a piece of galvanized pipe and putting an end cap on it. Then taking a piece of copper pipe, insulating one end with electrical tape and sliding it into the galvanized pipe so it doesn't touch. Fill the thing with tap water and BAM, you have a battery.

I have a new Fluke multimeter coming tomorrow, so I'm gonna start experimenting with home-made batteries and will let ya know what I learn. My goal is to be able to MacGyver batteries out of stuff you find laying around.
 

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I'm thinking more along the lines of taking a piece of galvanized pipe and putting an end cap on it. Then taking a piece of copper pipe, insulating one end with electrical tape and sliding it into the galvanized pipe so it doesn't touch. Fill the thing with tap water and BAM, you have a battery.

I have a new Fluke multimeter coming tomorrow, so I'm gonna start experimenting with home-made batteries and will let ya know what I learn. My goal is to be able to MacGyver batteries out of stuff you find laying around.
In all seriousness, please do let us know what you figure out. Homemade batteries are something that has interested me since I was a kid and I made a Radio Schlock one with a lemon.
 

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If you just whacking together a quick prototype for testing, could you just use PVC? It is cheap, easy to weld with the purple juice, and available everywhere. - Now you have me wondering. :?
That's my thought, it's the filter that does the work the rest is open to modification.
 

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Discussion Starter · #13 ·
I think there is a way to test this. Take a piece of PVC pipe big enough to hold the filter and maybe 2 feet long. Get a cap, drill it, then install the filter and jam the cap in place. Fill the tube with water and put a bowl under it to catch the water.

Then set a timer for like 15 minutes and wait. When the timer goes off, reset it and measure the water with a measuring cup or whatever. Do this every 15 minutes until it's all filtered.

If there is no difference in the amount of water, then the whole filter is being used all the time AND pressure doesn't matter.

If the output decreases over time, then increasing pressure increases flow.

At this point, you would have to plot the output vs time and look at the line. If the line connecting the data points is straight right to the end, then the whole filter is being used due to this "wicking action." If there is a "bend" (further drop in output) in the line once the filter top becomes exposed, then the whole filter isn't being used because the pressure depends entirely on the height of the water and should graph as a straight line.

I would bet that there would be a decrease in output over time, showing that pressure is a factor. I would also expect to see a bend in the line because I don't believe the whole filter is being used all the time, no matter what their customer service says.

Right now, I'm distracted with batteries and won't be able to try this for some time. If someone else wants to do it, please do!
 

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Discussion Starter · #14 ·
The graphs would look something like this...

output graphs.png

The first would be how it looks if pressure doesn't matter and the whole filter is being used all the time. The second would where pressure matters, but the whole filter is always being used. The last one would show that both pressure and filter coverage make a difference.

There should be a 4th case, where pressure doesn't matter but filter coverage does. In this one, it would be a horizontal line until the filter top is exposed, then output would drop off. Im' not gonna redraw the bloody thing to add it though, so use yer imagination. :)
 

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The graphs would look something like this...

View attachment 2310

The first would be how it looks if pressure doesn't matter and the whole filter is being used all the time. The second would where pressure matters, but the whole filter is always being used. The last one would show that both pressure and filter coverage make a difference.

There should be a 4th case, where pressure doesn't matter but filter coverage does. In this one, it would be a horizontal line until the filter top is exposed, then output would drop off. Im' not gonna redraw the bloody thing to add it though, so use yer imagination. :)
Placing my bet now based on nothing but intuition...

I expect the output to drop off some once the top of the filter is exposed to air. But, that does not necessarily mean the entire filter is not still filtering as there is less surface area of the filter exposed to water. Thus, the draw would be slower. I would expect a flat graph until the top is exposed then a more rounded graph as the water level drops. As I said, I do not base this on anything scientific, just a (hopeful) bet that the Berkey people did not lie to me.
 

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Discussion Starter · #16 ·
Inor, they so lied to you.

Actually, you might just have gotten one of those people who can't admit they don't know the answer. I'm thinking that, if it wicked up water, you wouldn't have to prime the filters. I freely admit I don't know this for sure, it's just a hunch.

Anyway, my bet is on the crooked line. I'm pretty sure pressure is all that moves water through any part of the filter.

So ask Mrs Inor if you can test it one way or the other please!
 

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Inor, they so lied to you.

Actually, you might just have gotten one of those people who can't admit they don't know the answer. I'm thinking that, if it wicked up water, you wouldn't have to prime the filters. I freely admit I don't know this for sure, it's just a hunch.

Anyway, my bet is on the crooked line. I'm pretty sure pressure is all that moves water through any part of the filter.

So ask Mrs Inor if you can test it one way or the other please!
HAHAHA! Will do sir. I am home this week so I will do the test as you prescribe. :p
 

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Filters aside, the Berkey spigot looks to be of the inexpensive variety, how do those hold up or should one look into replacing it from the get go...
 

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Prepadoodle - Inor can play with the Berkey after he finishes his cabinet in the garage so I can have the shelves he is replacing with said cabinet. Then I can finish cleaning up downstairs and we can put this place on the market.
 

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Inor, they so lied to you.

Actually, you might just have gotten one of those people who can't admit they don't know the answer. I'm thinking that, if it wicked up water, you wouldn't have to prime the filters. I freely admit I don't know this for sure, it's just a hunch.

Anyway, my bet is on the crooked line. I'm pretty sure pressure is all that moves water through any part of the filter.

So ask Mrs Inor if you can test it one way or the other please!
I am a terrible politician so don't flame me too bad for this.

I hate it when someone says "they lied to you" and in the next sentence say its just a hunch.

The bottom line is the Berkey is the best water filter out there for the money, I say quit dissing it on technicalities.
 
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