Replicating my own tap water

I finally got my water tested!

With the help of Ward Labs, now I know what minerals are in my tap water. For $48, they analyze any water you send them for the main important ions, plus iron and nitrate. I was really excited when I got the results, because they confirmed a lot of my hunches about its composition from simply tasting tea made with it and comparing with my various experiments. Without further ado, here is the composition of my local Massachusetts groundwater.

Calcium	18.2
Magnesium	6
Sodium	68
Potassium	6
Bicarbonate	29
Sulfate	21
Chloride	128
Silica	8.6
Nitrate	2.4
Iron	0.02

Hardness	70 mg/L as CaCO3
Alkalinity	13 mg/L as CaCO3
Hardness to Alkalinity Ratio	5.36
TDS (calculated, will not measure nearly this high due to ion conductivities)	268 ppm
Electrical Conductivity at 25ºC (calculated, expected to measure)	552 μS/cm
pH	6.9

It’s immediately apparent that there’s a lot of sodium and chloride in this water. I had a feeling this would be the case, as our roads are heavily salted in the winter and that all goes into the ground. I also had a sense that with such a high TDS, but no scaling, a lot of the mineral content would be salt. This salt doesn’t make it taste salty at this concentration, but does increase the mineral taste of the water and adds a bit of viscosity.

The other strange thing about this water is the high Hardness to Alkalinity ratio of 5.36. This is caused by medium calcium and magnesium but very low bicarbonate. I’ve never seen a hardness to alkalinity ratio this high in a natural water – they are almost always between 0.5 and 1.4. But, this is proof that water comes in all different shapes and sizes. When I make tea with my tap water, I notice that it does lack some of the deep texture that it would have with more bicarbonate, doesn’t scale as it would with more bicarb, and has very present flavor and brightness, as those bright acidic tastes are not buffered by any bicarbonate alkalinity. It’s not particularly harsh water despite this high H:A, it’s actually really smooth and enjoyable. The silica in there is a nice bonus, too.

Cupping the replica tap vs the real thing

I decided to replicate the tap water with distilled water and various salts, down to the milligram. I even added some eidon silica concentrate. Then, I used a cupping set to see if there was a difference – I want to see how fake water stacks up to the real thing!

I used a dancong from Yunnan Sourcing to do this comparison, with 3.1 grams in each 150ml mug, steeping for 5 minutes. The fake tap came out a bit darker than the real tap, but it was pretty close.

Despite my criticisms of the remade tap, they were fairly similar, with the same general idea – high fragrance, high minerality, low alkalinity. The flavors were similar as well. I have a theory why they were so different – I used sea salt instead of pure salt. Sea salt is 30 percent magnesium chloride. Whoops! So, to anyone making a mineral recipe with salt, including Truth Serum, it makes a big difference if you use pure NaCl (which is hard to find without anti-caking agents, but there’s a link in the Water Guide). This experiment will be worth repeating in the future with pure NaCl.

What did I learn?

The general takeaway, besides the impurity of sea salt, is that fake water is an approximation, and there are many factors that make natural water superior to it. (Edit: this is to say, given the same mineral profile. An artificially made good mineral profile is better than a naturally bad one.) Now that I know the mineral content of my tap water, I can make small (or large) adjustments to it to modify how it behaves with tea. I really appreciate that my tap has good amounts of sulfate and chloride, as I can always fall back on it for a decent cup of tea.

Sorry for being so slow on the water guide, there’s a lot to type. It will get done though! Let me know if you get your tap tested, and what the results are!