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

July 29, 2024 5 min read

What Is the pH of Distilled Water and Tap Water?

When it comes to water quality, pH is one of the first things people check. A common question is: is distilled water acidic? The simple answer is that pure distilled water is neutral at the point of distillation, but it can become slightly acidic once exposed to air.

In its purest state, water has a pH of 7, which is neutral. Most drinking water usually sits somewhere between 6.5 and 8.5 depending on the minerals, treatment process and source water. So what is the real pH of distilled water compared with tap water, and does it matter for everyday drinking?

Quick answer: Freshly distilled water is close to pH 7, but it often measures around 5.5 to 6.9 after it absorbs carbon dioxide from the air. Australian tap water is usually closer to 6.5 to 8.5, depending on your local supply.

If you want very low TDS water at home, our water distillers and steam purifiers are designed for steam-based purification.

For a deeper look at how distillation works, you can read our Water Distillers Guide. If you are comparing distillation with a plumbed-in filtration option, our Reverse Osmosis Guide explains the main differences.

What Is pH?

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

For drinking water, pH does not tell the full story by itself. Taste, dissolved minerals, chlorine, filtration method and total dissolved solids can all affect how water feels and tastes.

The pH of Distilled Water

Distilled water should theoretically have a pH of exactly 7.0 because it is purified water with most dissolved minerals and contaminants removed. In real-world conditions, distilled water is often slightly acidic, commonly measuring somewhere between 5.5 and 6.9.

This happens because distilled water readily absorbs carbon dioxide from the air. Once carbon dioxide dissolves into the water, it can form a small amount of carbonic acid:

CO₂ + H₂O → H₂CO₃

This mild acidification is natural. It is similar to the way rainwater can become slightly acidic after contact with air. It does not automatically mean distilled water is unsafe to drink.

pH of distilled water compared with tap water

Water Distillers & Steam Purifiers

Boil, capture the steam and condense it back into very low‑TDS purified water — the most direct option when dissolved solids are your main concern.

Shop distillers →

Best option for low TDS water: Distillers boil water, collect the steam and condense it back into purified water. This makes them a practical choice when your main goal is very low dissolved solids rather than simply changing pH.

For home use, browse our range of water distillers in Australia.

The pH of Tap Water

Australian tap water is usually managed to sit within a suitable drinking range, commonly around pH 6.5 to 8.5. The exact result can vary by city, catchment, treatment process, pipework and local mineral content.

Sydney and Melbourne: Often closer to neutral, depending on the water source and treatment process.
Adelaide and Perth: Can be harder or more alkaline in some areas because of local source water and mineral content.
Bore and tank water: Can vary widely, so testing is recommended if you rely on these sources.

Many households are less concerned about pH itself and more concerned about chlorine taste, odour, sediment or dissolved solids. For everyday taste improvement, an 8-stage KDF water filter can be a practical option for drinking water.

8 Stage KDF Water Filter

A practical everyday choice for reducing chlorine taste and odour in your drinking water.

Shop 8‑stage filters →

Distilled Water vs Tap Water pH

Water Type	Typical pH	Why It Varies
Fresh distilled water	Close to 7	Very low mineral content after distillation.
Stored distilled water	Often around 5.5 to 6.9	Absorbs carbon dioxide from the air, which can slightly lower pH.
Australian tap water	Often around 6.5 to 8.5	Affected by minerals, treatment, pipework and local source water.
Reverse osmosis water	Can be slightly acidic	Low mineral content can make the pH more sensitive to air exposure.

What Happens If Water pH Is Not Balanced?

Water that is very acidic may taste sharp and, in some plumbing systems, may contribute to corrosion over time. Water that is too alkaline can taste flat, bitter or mineral-heavy. For most homes connected to town water, pH is usually managed by the local water supplier.

If you use bore water, rainwater or tank water, testing is a smart first step. A test can show whether the concern is pH, hardness, sediment, bacteria, dissolved solids or another water quality issue.

If your main concern is dissolved solids, fluoride or a wider range of contaminants, a reverse osmosis water filter system may be a better fit. If you specifically want steam-purified, very low TDS water, a water distiller or steam purifier is usually the more direct option.

RO 4000 Benchtop Reverse Osmosis Water Filter System with American Alkaline

Reverse Osmosis Systems

A plumbed‑in option that reduces a wide range of dissolved solids and contaminants through a dedicated tap.

Shop RO systems →

How to Improve Your Water's pH and Taste

For chlorine taste and odour: Choose a carbon or KDF-style filter designed for everyday drinking water taste improvement.
For low TDS purified water: Choose a distiller if you want steam-purified water with most dissolved solids removed.
For dissolved solids and fluoride reduction: A reverse osmosis system can be suitable, depending on your household needs and installation preference.
For alkaline-style water: Mineral media such as magnesium prill beads may help raise pH naturally.

Magnesium Prill Beads

Reusable mineral media that may help raise the pH of your water naturally for an alkaline‑style result.

Shop prill beads →

Not sure whether you need a filter, RO system or distiller?

Start with your main goal. Choose a water filter for better taste, reverse osmosis for dissolved solids and fluoride reduction, or a distiller for very low TDS purified water.

You can compare our water distillers with our reverse osmosis systems to decide which setup suits your home best.

Frequently Asked Questions

Is distilled water safe to drink?

Yes, distilled water is safe to drink for most people. The slightly acidic pH that can occur after air exposure is not usually a safety issue. The main difference is that distilled water contains very few minerals, so long-term exclusive use should be considered alongside your diet and personal needs.

What pH is best for drinking water?

Most drinking water is commonly managed around pH 6.5 to 8.5. Many people prefer water that tastes close to neutral, but taste also depends on minerals, chlorine, filtration and dissolved solids.

Does a water filter change pH?

Most standard carbon and sediment filters do not dramatically change pH. Reverse osmosis can produce slightly acidic water because it removes many dissolved minerals. Alkaline stages, mineral cartridges and magnesium media can raise pH depending on the system design.

Is distilled water more acidic than tap water?

It can be. Distilled water often becomes slightly acidic after it absorbs carbon dioxide from air. Tap water usually contains minerals and treatment chemicals that can keep pH closer to neutral or slightly alkaline, depending on your local supply.

Should I choose a distiller or reverse osmosis system?

Choose a distiller if you want very low TDS water made through steam purification. Choose reverse osmosis if you want a plumbed-in system that reduces many dissolved contaminants and supplies filtered water through a dedicated tap.

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