# Drip vs Immersion



## the_partisan (Feb 29, 2016)

Matt Perger posted this video comparing immersion & drip extraction:






I thought his math and reasoning is a bit dodgy. 230g @ %1.08 TDS is 2.4g, while 200g @ %1.5 TDS is 3g of dissolved solids.

Hence the main reason in my opinion would be that, drip is much more efficient/quicker at extraction due to constant supply of fresh water than the logic that remaining water has the same TDS.

Any thoughts?


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## The Systemic Kid (Nov 23, 2012)

Think MP is using the formula: output/dose x tds measurement. So, 200/15 x1.5 = 20% extraction yield. Punching figures into VST software gives an EY for drip of 21.25% and 20.3% for immersion.

His explanation why you include the full amount of water used in the calculation for immersion is helpful.


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## the_partisan (Feb 29, 2016)

So he is saying the 30g of water in the filter has 0 dissolved solids. So there is a total of 200*0.015=3g of dissolved solids, out of the 15g. That is EY of 20%.

However, in the aeropess, you would have uniform TDS across the board so 230*0.0108=2.48g of dissolved solids, which would be EY of 16.5%. His TDS in the Aeropress would have to be 1.3% for the numbers to add up..


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## MWJB (Feb 28, 2012)

the_partisan said:


> So he is saying the 30g of water in the filter has 0 dissolved solids. So there is a total of 200*0.015=3g of dissolved solids, out of the 15g. That is EY of 20%.
> 
> However, in the aeropess, you would have uniform TDS across the board so 230*0.0108=2.48g of dissolved solids, which would be EY of 16.5%. His TDS in the Aeropress would have to be 1.3% for the numbers to add up..


You're quite right. His TDS% in the immersion example is wrong.

"Efficient" might not be the phrase I'd use, you can hit the same strength via drip or immersion, but the immersion will take longer (so drip is faster) & calculate as a higher EY. I have no idea why 20%EY, or the same brew time as drip, would be a target for an immersion.


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