Water pH - Discrepancy between Ward Report and ph Meter

[matchrocket]

Moved to a new house recently and had my water tested from Ward Labs. My pH meter was down when I ordered (electrode died) and got it back up and running today.

On my water report (below) my pH was surprisingly low, I decided to check it with my meter, freshly calibrated. Water was pulled from the same source. The difference was huge.

My meter reads 7.48 vs Ward 6.6... I am inclined to trust my meter. Why is there such a huge difference? My Meter reads back same pH as calibration solution (which was close to begin with) What gives?

pH 6.6
Total Dissolved Solids (TDS) Est, ppm
Sodium, Na 23
Potassium, K 2
Calcium, Ca 36
Magnesium, Mg 5
Total Hardness, CaCO3 111
Sulfate, SO4-S 16
Chloride, Cl 19
Carbonate, CO3 < 1.0
Bicarbonate, HCO3 89
Total Alkalinity, CaCO3 73

 

[jayjaytuner]

this is city water? how long did you let the water run before you took sample?

 

[matchrocket]

City water, both times ran the faucet at a steady stream for ~5m, on cold.

 

[dyqik]

It's not uncommon for city water to change throughout the year as different sources are used, or as aquifers and lakes fill from snow-melt in spring.

It'd be a good idea to get a cheap aquarium hardness test kit to see if the alkalinity/hardness has changed as well. They're about $8 on Amazon. Alkalinity is more important than pH for mash chemistry although variations in one will go with variations in the other.

EDIT: Your city water dept. (assuming that your profile is accurate and you are in Meridian) says that the average hardness is 7 grains per gallon, or 119 ppm, which jibes well with the Ward report number. But the 2015 water report (pg 9) says that different neighborhoods vary between 4.3 and 7.9 grains per gallon, so you've got a potentially large variation in hardness and thus alkalinity and pH as water is distributed from different sources through the city. It's definitely worth getting the hardness test kit.

You probably should look at http://braukaiser.com/wiki/index.php/At_home_water_testing to see how to use a test kit to deal with variable water.

 

[matchrocket]

Thanks. I think I am going to move back to RO For the mash water due to my high alkalinity... This really peaked my interest due in regards to acidifying the sparge water.