I have been trying to figure out the right mixture of tap water and treated water (thru brita) to put in the pour over.

My mind is hurting from trying to make sense. I know someone here knows something, so if they could help it would be greatly appreciated.

Here's the equations

Tap water hardness is 140ppm

Brita hardness is "unmeasurable" shows "0" or let's call it "X"

If I mix 1 part tap water with 1 part brita water = 90ppm (1/2 + 1/2)

If I mix 1 part tap water with 2 parts brita water = 60ppm (1/3 + 2/3)

If I mix 1 part tap water with 3 parts brita water = 50ppm (1/4 + 3/4)

What is the brita water hardness or "X" ?

Brita hardness (B) is between 0 and 20 ppm, depending on which pair of readings you use to do the calculation.

Taking the first and second readings together says B = 0, T = 180.

Taking the second and third readings together says B = 20, T = 140.

Jim

Jim,

I knew someone here would help me, but I don't understand the reasoning.

We know that the Tap water is 140ppm T = 140 and that is absolute

But

There is another variable which is why is the Brita or B is not constant with varying amounts of Tap water ?

misterdoggy wrote:There is another variable which is why is the Brita or B is not constant with varying amounts of Tap water ?

Probably just measurement tolerances -- I'm guessing +/- 10 ppm? If the 90 ppm you measured in test 1 was actually 80 ppm, then you would have consistent results at B = 20 and T = 140 in each test.

Jim

Thanks Jim,

So that would mean if my aim was to arrive at 50ppm then I would have to mix

3 parts of 20ppm with 1 part of 140ppm ?

which does equate hmmmmm

In my mind it makes 4/4 or

5ppm + 5ppm + 5ppm + 35ppm = grand total 50ppm

So you are right in saying its 20ppm

thanks so much. 20 ppm is too low for good coffee and needs some minerals .... I will have to mix

misterdoggy,

I recommend you get an inexpensive TDS meter. In the USA, they're available online for about $25 or less. If you can get a ZeroWater pitcher in France, it comes with a TDS meter. You can find them at amazon.com (don't know if they ship to France.)

The numbers could be varying if the hardness of your tap water varies. I get slightly different TDS readings on my tap water at different times. Our well water has large amounts of sediment that's filtered out by a 5-micron whole-house filter but passes dissolved minerals. I've noticed that the amount of sediment varies over time, and it's possible that the concentration of dissolved minerals varies along with it. Anorther possibility is that there are small variations in the amount of filtering done by your Brita.