Would I actually need a new water report?
Wouldn't distilled water have essentially 0 ppm in all the categories?
If I used half distilled water, and half of my tap water, wouldn't that cut all my ppm values in half?
I could send a vial of distilled water to Ward labs, but not sure it would be useful.
Yeah you don't really need a new water report. But be sure to test the pH of the distilled water. It should be 7 or slightly below or above, depending on the temperature when you test it and if the water has been exposed to the atmosphere, usually it will be a bit less than 7.
IF you make your own distilled water you might still need a water report if you're looking for the perfect water for a certain beer. When you buy distilled water you're virtually sure it doesn't contain any minerals, when you make your own some might be left behind but usually not enough to make a real difference. The only thing that could be a problem in that scenario is that you don't know the exact alkalinity (caco3/HCO3) But it should be really low.
I did some calculations for you,
If you dilute 50/50 with distilled water it should look something like this:
It's basically dividing by two
Calcium: 52
Magnesium: 25
Sodium: 11
Sulfate: 7
chloride: 21
Bicarbonate: 251
However, you might want to get the bicarbonate even a bit lower. you you would have to use a dilution of 40/60:
calcium: 41
magnesium: 20
sodium: 8
Sulfate: 5
Chloride: 17
Bicarbonate: 201
You see, the problem when you dilute water is that you always have to get the highest value, in this case the bicarbonate to the desired value. But while doing this all the other minerals in the water are also altered.
So, If you know what you want to brew you have to alter the water profile until it's right for the kind of beer you want.
For example:
From that site i linked last time under water target selection I'm gonna pick balanced profile 2, because i like darker beers
CA: 150 Mg: 10 Na: 80 Cl: 150 SO: 160 and HCO: 220 ppm
So let's look at the bicarbonate we need: your water profile has a bicarbonate level of 501 ppm. and we would need 220 ppm.
So now we calculate how much we need to dilute your tap water and If we use 45% tap water and 55% distilled water we get to 226 ppm bicarbonate.
And that's pretty close.
diluted water profile:
CA:46 Mg:22 Na:9 Cl:19 19 SO:6 and HCO: 220 ppm
Now the problem is that we also diluted the rest of the minerals. And to get these back to the correct amount you need for that water profile you would need to make certain additions. You can find those online, I don't want to make this post longer than it already is.
I think if you would dilute 50/50 or 45/55 you could make a decent amber or dark beer without adding to much. If you want lighter beers you would basically want to dilute the distilled water with some of your water