Why water type matters more than anything else.
Every hydrogen inhaler we sell runs on a Proton Exchange Membrane / Solid Polymer Electrolyte stack. The membrane is a precision polymer film that splits water into hydrogen and oxygen at the proton level. It is built to handle one thing — pure H₂O — and is intolerant of everything else.
Dissolved minerals (calcium, magnesium, sodium, iron, chlorine, fluoride) precipitate inside the cell as the electrolysis reaction concentrates them. The scale coats the catalyst, blocks proton transport, drops gas purity below the 99.991% spec, and within weeks to months kills hydrogen output. There is no recovery — a scaled stack is replaced, not cleaned.
This is the single most common cause of warranty claims across every brand of hydrogen machine, ours included. It is also the easiest fault in the world to avoid: use the right water from day one.
The short answer.
- Use: distilled water, deionised (DI) water, or double-distilled water.
- Acceptable in a pinch: reverse-osmosis (RO) water that reads under 5 ppm on a TDS meter.
- Never use: tap water, spring water, mineral water, filtered tap water, alkaline water, hydrogen-rich water, or any bottled drinking water other than distilled.
Safe water types, in detail.
Distilled water
The default recommendation. Distillation boils water and condenses the vapour, leaving every dissolved mineral behind. Supermarket distilled water in Australia typically reads 0–2 ppm TDS and is suitable straight from the bottle. Stock a four-litre jug under the sink and you are set for weeks.
Deionised (DI) water
DI water is passed through ion-exchange resin that strips dissolved ions. The chemistry of the finished product is interchangeable with distilled for our purposes. Common at pharmacies, lab supply shops and hydroponics stores.
Double-distilled water
Distilled twice. Reads 0 ppm and contains the smallest possible level of dissolved gases and organic carry-over. Not necessary for normal use, but excellent for very long stack life on a high-hours machine.
Water types to avoid — and exactly why.
Tap water
Typical Australian tap water reads 100–300 ppm TDS, with regional supplies (parts of Adelaide, Perth, and remote bores) running 400–600 ppm. It contains chlorine or chloramine, fluoride, calcium and magnesium hardness, and trace metals from plumbing. Every one of these damages the stack. Even a single tank of tap water can deposit visible scale.
Spring water and mineral water
Counter-intuitively, the more "natural" and "mineral-rich" the water, the worse it is for an electrolyser. Premium European mineral waters can read 500–1,500 ppm TDS. Bottled spring water in Australia typically reads 100–400 ppm. These are excellent for drinking and terrible for the machine.
Filtered tap water (jug, fridge, under-sink carbon)
Activated carbon filters remove chlorine, sediment and most taste compounds. They do not remove dissolved minerals. A jug-filtered glass of water can still read 150+ ppm. Use it for drinking; do not use it in the machine.
Alkaline water and hydrogen-rich water
Both are tap or filtered water with additional minerals or dissolved hydrogen added. The added minerals (in alkaline ionisers) are exactly the contaminants the membrane cannot handle.
Reverse osmosis (RO) — the edge case.
A good home RO unit removes 95–99% of dissolved solids. With a fresh membrane and good source water, you can see readings as low as 5 ppm. With an older membrane or poor source water, the same unit might read 30–50 ppm. The variance is the problem.
The safe rule: if your RO is paired with a DI polishing stage (common in aquarium and lab installations), the output is 0–2 ppm and fully safe. If it is RO only, test with a TDS meter before every refill. If it reads above 10 ppm, swap to distilled.
How to check your water with a TDS meter.
A TDS (total dissolved solids) meter is a pen-sized probe that reads dissolved mineral content in parts per million (ppm). They cost AUD $15–25 from any aquarium, hydroponics or homebrew shop, last for years on a coin-cell battery, and remove every guess from this question.
- Fill a clean glass with the water you intend to use.
- Turn the meter on and dip the probe 2–3 cm into the water.
- Wait 5 seconds for the reading to stabilise.
- Read the number on the screen.
- 0–5 ppm — ideal. Use freely.
- 5–10 ppm — acceptable. Safe for normal use.
- 10–30 ppm — borderline. Will gradually scale the stack over months. Avoid for long-term use.
- 30+ ppm — do not use. Switch to distilled.
Refilling, rinsing and storage.
Drain the reservoir, rinse twice with fresh distilled water, and refill at least every 20 days under daily use. If you see cloudiness, sediment or any discolouration, change it immediately — that is contamination, not the machine "working harder".
Between sessions, leave a small amount of distilled water in the reservoir so the membrane stays hydrated. A fully dry PEM membrane can crack on rehydration, which permanently lowers gas output and is not covered under warranty. If storing the unit unused for more than two weeks, top up to the minimum fill line rather than draining it.
What this looks like in practice.
Buy a 4 L jug of distilled water from the supermarket (around AUD $4). Keep a TDS meter in the drawer. Refill the machine every 20 days. That is the entire water-care routine, and it is the single most effective thing you can do to keep your inhaler producing 99.991% pure hydrogen for years rather than months. For everything else about caring for the machine, see the how hydrogen inhalation works guide and the Technology page.
If you would rather not keep buying jugs, a reverse-osmosis system at the tap is the other route to consistently low-TDS water. The HERO Purity 200-110 uses three-stage filtration (PP sediment, CTO carbon block, RO membrane) ahead of its own PEM cell, and the RO systems hub sets it beside the HERO RO Dual 10. Still check the output with your TDS meter before filling an inhaler — RO output varies with membrane age and feed water.