Water Quality for HHO Electrolyte: Why Distilled Matters

What Tap Water Contains

Typical US municipal tap water contains 100–500 ppm of dissolved solids: calcium, magnesium, chloride, sodium, fluoride, and other minerals. During electrolysis, these minerals concentrate in the electrolyte as water is consumed. Calcium and magnesium form scale on plate surfaces. Chloride ions attack stainless steel. Fluoride interferes with the electrolysis reaction.

TDS Testing

A TDS (total dissolved solids) meter ($10) measures water quality in ppm. Distilled water should read 0–5 ppm. Reverse osmosis water: 5–20 ppm (acceptable). Tap water: 100–500 ppm (not acceptable for HHO). Rainwater: varies 5–50 ppm depending on atmospheric pollution (marginal). Only verified distilled water ensures clean long-term operation.

Distilled Water Sources

Grocery store distilled water (by the gallon): $0.80–$1.50/gallon — convenient and consistent. Home water distiller ($60–$150): produces 1 gallon/hour from tap water, pays back in 100 gallons. Automotive stores: often stock distilled water (used for battery maintenance). Steam iron water marked "distilled": same product, often slightly cheaper.

Electrolyte Refresh Interval

With distilled water and fresh KOH, electrolyte remains usable for 6–12 months under normal conditions. Check electrolyte clarity monthly — if it's turning brown or cloudy, it's accumulating metal ions from plate corrosion and needs replacement. Complete electrolyte change every 6 months is good practice regardless of appearance.