Finding out water profile when using more than one water source

[Benfleet Brewery]

Ok, probably more a maths question than a water one but this somehow has me stumped.
I often use a combination of RO and tap water as a starting point for my brew water then adjust as required. So, as an example, The way I work out the starting point when using 50% RO and 50% tap water is to half the Ca, SO4, CL and CaCO3 amounts in my tap water, correct?
Anyway, this weekend I’m planning to use a combination 50/50 of tap water and ASDA spring water but can’t for the life of me work out what I need to do. I’m thinking that I just half the salts of my tap water and then add those contained in the ASDA water. So, for example, Tap water Calcium 10l @ 130ppm, ASDA 10l @ 13ppm = 20l @ 78ppm?? Is that right?

 

[Agentgonzo]

Correct

 

[YeastFace]

I have a spreadsheet to do calculate final salts when I mix water sources, not sure I can attach though?

Essentially all you need to do is add up the PPM per salt from each water source and then divide by 2 (when using 50% of each water).

E.g

Tap water Calcium - 50ppm
Asda water Calcium - 30ppm

Mixed water calcium - 40ppm (50+30/2)

 

[Benfleet Brewery]

I have a spreadsheet to do calculate final salts when I mix water sources, not sure I can attach though?

Essentially all you need to do is add up the PPM per salt from each water source and then divide by 2 (when using 50% of each water).

E.g

Tap water Calcium - 50ppm
Asda water Calcium - 30ppm

Mixed water calcium - 40ppm (50+30/2)

Ah, yes, of course. So bloody obvious now. Thank you.

 

[Hazelwood Brewery]

Ok, probably more a maths question than a water one but this somehow has me stumped.
I often use a combination of RO and tap water as a starting point for my brew water then adjust as required. So, as an example, The way I work out the starting point when using 50% RO and 50% tap water is to half the Ca, SO4, CL and CaCO3 amounts in my tap water, correct?
Anyway, this weekend I’m planning to use a combination 50/50 of tap water and ASDA spring water but can’t for the life of me work out what I need to do. I’m thinking that I just half the salts of my tap water and then add those contained in the ASDA water. So, for example, Tap water Calcium 10l @ 130ppm, ASDA 10l @ 13ppm = 20l @ 78ppm?? Is that right?

Not quite. You just need to think that you have a total amount of calcium dissolved in a total amount of water.

From your tap water you have 1,300g
(10 x 130 = 1,300)

From your bottled water you have 130g
(10 x 13 = 130)

In total you have 1,430g calcium in 20 litres of water

1430 / 20 = 71.5g/l = 71.5ppm

 

[Benfleet Brewery]

Not quite. You just need to think that you have a total amount of calcium dissolved in a total amount of water.

From your tap water you have 1,300g
(10 x 130 = 1,300)

From your bottled water you have 130g
(10 x 13 = 130)

In total you have 1,430g calcium in 20 litres of water

1430 / 20 = 71.5g/l = 71.5ppm

Got it, thank you

 

[aamcle]

You can always use the brewersfriend.com advanced water calculator.