pH of water is greater than 8.0

[Taket_al_Tauro]

One way to guestimate alkalinity is a simple aquarium test, about $5 at Walmart. It won't give you everything you need (calcium, sulfate, calcium chloride, sodium) but I use it to see if my RO water filter is working properly. One drop from the reagent confirms that it is. You can try that- but your mash pH of 8 is immaterial as it could simply have absorbed CO2 by the water sitting out.

Guestimate? IME those drop tests are pretty reliable. As you mentioned they are cheap and also very easy to use. Actually I don't really unterstand why they aren't more popular among homebrewers. They are more valuable than a pH-meter, IMHO, which I do also have, but could almost do without in the meantime. Those tests have become an essential part of my brewing water adjustements, because my water supply is extremely variable with respect to hardness/alkalinity (they blend water from two sources with starkly different profiles). Needless to say, a single water analysis/report would be totally useless in my case (and I suspect I am not the only one in the world who is getting tap water with variable chemical profiles). Given that I did not want to go the distilled/RO water route, I now measure the alkalinity of my water with one of those drop tests before each brew day. I've seen alkalinity values ranging between 150 and 260 ppm, and everything inbetween. Then I plug the value in my calculator (Bru'n Water), and I'll know exactly how much acid I need to add to achieve a given target mash pH. I was able to hit my mash pH ballpark very consistently even with those extremely variable starting alkalinity values. So I concluded than both the alkalinity tests and the water calculator must be pretty accurate.

 

[Yooper]

Guestimate? IME those drop tests are pretty reliable. As you mentioned they are cheap and also very easy to use.

I say "Guestimate" because you get a range. It's a good range, in my case I get "less than 17 ppm" but it could be 2 or it could be 16.9. Either way, it's not a meaningful amount nor a meaningful difference. It also depends on your eyesight, and detection of colors, and I do it over white paper.

It's great for continuing to check my RO water dispenser, as if the hardness increases, I'll know to change the membrane.

 

[Taket_al_Tauro]

I say "Guestimate" because you get a range. It's a good range, in my case I get "less than 17 ppm" but it could be 2 or it could be 16.9. Either way, it's not a meaningful amount nor a meaningful difference. It also depends on your eyesight, and detection of colors, and I do it over white paper.

The alkalinity test I have does show a very evident color switch that is almost impossible to miss. The total hardness test is a bit more tricky, with a much more subtle/faint color switch. I think it has gotten worse with age and it's probably time to replace it. But the alkalinity test is still spot-on and very easy to handle, even if the test solution is at least two years old now. And the alkalinity one is the most important by far... I only use the hardness test to get a rough estimate of my Ca- and Mg concentrations.
But I am based in EU so we may also have different test kits. Mine are also a bit more expensive than 5$, but not by much....

 

[alan sabatke]

I moved to a new house a couple of years ago and had off flavors so bad I had to dump many batches. Got a wards water test and ph is at 8.1 and is fairly hard. Started adding 2 gals RO water for every 3 gals well water and beer is back to fantastic! I have a cooling coil in my fermenter which I circulate cool well water through, thermostat controlled, so hot fermentation was not a cause with off flavors. Wish I had learned sooner about the high ph, lost a couple of 15 gal batches, what a waste!!

 

[z-bob]

There is a local microbrewery and tap room that uses the local tapwater and just filters it through a carbon block to remove chlorine. Most of their beers range from bad to terrible, but I've had a double stout there that was actually pretty good.

Most of the homebrewers here don't even try to use tapwater, they either have an RO machine or buy bottled water. The good microbreweries use a mixture of RO water and tapwater. I use straight tapwater but I have to add a lot of acid. Someday I want to try using calcium hydroxide to soften the water, then add just a little acid to the mash.