How effective is hydrochlorothiazide (microzide) for treating hypertension?

Diuretic (H2O) pill: Hydrochlorothiazide (HCTZ) has been the 1st line, go-to-drug for treating hypertension for a long time. For those w/mild elevations, it can be quite effective by itself. It's effectiveness is additive when used in combination w/other blood pressure lowering medications in other classes, eg ACE inhibitors, ARBs, beta-blockers, calcium channel blockers, etc. Check out http://www.drugs.com/hctz.html