Understanding 9.5 pH Water Meaning: Distilled vs. Tap Water Insights

What Is the pH of Distilled Water and Tap Water?

When it comes to water quality, understanding pH levels is essential. A common question is: is distilled water acidic? The answer lies in how distilled water interacts with its environment.

In its purest state, water has a pH of 7 — perfectly neutral. But most drinking water sits between 6.5 and 8.5 depending on what's dissolved in it. So what's the actual pH of distilled water and tap water — and does it matter?

For a deeper look at distillation and how it works, see our Water Distillers Guide. If you're comparing purification methods, our Reverse Osmosis Guide is also worth reading.

What Is pH?

pH is a scale from 0 to 14 that measures how acidic or alkaline a solution is. Below 7 is acidic, above 7 is alkaline, and 7 is neutral. It's used across chemistry, medicine, agriculture, food production, and water purification.

The pH of Distilled Water

Distilled water should theoretically have a pH of exactly 7.0 — pure H₂O with nothing else in it. In practice, it's usually slightly acidic, with a pH between 5.5 and 6.9.

Why? Because as soon as distilled water is exposed to air, it absorbs carbon dioxide (CO₂), which dissolves to form carbonic acid:

CO₂ + H₂O → H₂CO₃ (carbonic acid) → HCO₃⁻ + H⁺

This mild acidification is natural and harmless — it's the same process that makes rainwater slightly acidic. It doesn't make distilled water unsafe to drink.

The pH of Tap Water

Australian tap water typically has a pH between 6.5 and 8.5 — the range considered safe for drinking by Australian Drinking Water Guidelines. The exact pH varies by city and water source:

• Sydney and Melbourne: Generally 7.0–8.0 (soft, mountain catchment water)
• Adelaide and Perth: Can be higher due to harder, more alkaline source water
• Bore and tank water: Highly variable — testing recommended

Chlorine is added during treatment, which can affect both pH and taste. An 8-stage KDF water filter removes chlorine and improves taste without significantly altering pH.

What Happens If pH Isn't Balanced?

Water that's too acidic (below 6.5) can corrode pipes and leach lead or copper into your water. Water that's too alkaline (above 8.5) can taste flat or bitter and may affect how your body absorbs certain minerals.

For most Australians on town water, pH is within safe range. If you're on bore or tank water, it's worth testing. A reverse osmosis system or water distiller will produce the most consistent, neutral-pH water.

How to Improve Your Water's pH

• For chlorine and taste issues: An 8-stage KDF benchtop filter is the most practical solution for most households.
• For maximum purity and consistent pH: A water distiller produces the purest water possible.
• For dissolved solids and fluoride: A reverse osmosis system removes up to 99% of dissolved contaminants.
• For alkaline water: Magnesium prill beads raise pH naturally.

Frequently Asked Questions