My well water is pretty alkaline. Last year I had a couple brews turn out a bit on the astringent side and I attributed it to the unadjusted sparge water (Batch Sparge). Since that time I adjust it with lactic acid to get the pH down around 6.5 and have not had the problem since. For comparison here's what my water looks like from Ward Labs:
pH 7.6
Total Dissolved Solids (TDS) Est 274
Electrical Conductivity, mmho/cm 0.46
Cations / Anions, me/L 5.2 / 5.1
Sodium, Na 7
Potassium, K 5
Calcium, Ca 77
Magnesium, Mg 10
Total Hardness, CaCO3 234
Nitrate, NO3-N 1.0 (SAFE)
Sulfate, SO4-S 3
Chloride, Cl 5
Carbonate, CO3 <1
Bicarbonate, HCO3 287
Total Alkalinity, CaCO3 236