Total Alkalinity of Water

Your water’s ability to resist pH swings.

Alkalinity is your water’s shock absorber: dissolved carbonates and bicarbonates that keep pH from swinging. When it’s too low, water turns unstable and corrosive — which is how metals end up leaching from pipes. It’s the quiet marker that protects all the others.

What it is

Total alkalinity measures the carbonate and bicarbonate minerals that neutralize acids in water. It’s related to hardness — both come from the same rock — but they answer different questions: hardness is about mineral load, alkalinity about stability.

How it varies

Like hardness, alkalinity comes mostly from local geology. Rainwater and snowmelt-fed supplies tend to run low; groundwater from carbonate rock runs high.

What a result can tell you

The commonly recommended range is 75–150 mg/L. Below that, water is prone to acid swings and corrosion — a finding that matters most alongside low pH or detectable copper and lead, since it points to the underlying cause. Above the range, expect the same scaling tendencies as hard water.

What it can’t tell you

Alkalinity has no direct health significance at normal levels — it’s an infrastructure and stability marker. Its value is diagnostic: paired with pH, it tells you whether your water chemistry is working for your plumbing or against it.