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Bottled water for fish tanks: soft and hard options

Dechlorinated tap water is the norm. If you use bottled, match it to your fish: soft-water or hard-water species.

Criterion: Still, unflavoured spring, mineral or artesian water with published TDS or dry residue of 100 mg/L or less and published calcium and magnesium, from the brand’s own verified analysis. Lowest first. Distilled and purified waters are left out because they need minerals added back before fish can live in them.

Test GH, KH and pH and acclimatise fish slowly whatever water you use. Ask an aquatic vet or specialist for sensitive species.

Why it matters

Extension services treat dechlorinated tap water as the normal choice: chlorine and chloramine must be removed before fish go in. Bottled water is rarely needed. Distilled and reverse-osmosis waters have almost no minerals or buffering, so they are only used after remineralising or mixing. Spring waters vary, so test GH, KH and pH; soft-water fish (such as many tetras) and hard-water fish (such as livebearers and African cichlids) need different water. Never use flavoured, sparkling or electrolyte waters.

Sources (2)
Top 20 of 63 qualifying waters · per litre, as publishedCompare the top 3 →

Soft, low-mineral water: TDS 100 mg/L or less

#WaterCalciumMagnesiumpHCompare
1Signature SpringsUSA0.55 mg/L0.42 mg/L6.79Compare
2LauretanaItaly1 mg/L0.37 mg/L6.9Compare
3Himalayas Spring WaterNepal1.2 mg/L0.48 mg/L6.68Compare
4Pedra AzulBrazil1.02 mg/L0.49 mg/L5.25Compare
53 Springs WaterUSA1.4 mg/L0.99 mg/L6.5Compare
6Acqua PloseItaly2 mg/L1.4 mg/L6.6Compare
7SpareaItaly3.8 mg/L0.53 mg/L7.1Compare
8Gond WanaParaguay0.4 mg/L0.24 mg/L—Compare
9BezoyaSpain6.32 mg/L0.83 mg/L—Compare
10NirvanaUSA8.8 mg/L0.39 mg/L6.6Compare
11Poland SpringUSA4.2–11 mg/L0.92–2.3 mg/L6.2–7.5Compare
12Saskia (Kirkel)Germany3.3 mg/L0.87 mg/L6Compare
13AmorosaItaly0.9 mg/L1.2 mg/L6Compare
14Lofoten Arctic WaterNorway1.6 mg/L1.1 mg/L6.8Compare
15CaxambuBrazil2.45 mg/L0.45 mg/L5.05Compare
16MontcalmFrance3 mg/L0.7 mg/L—Compare
17Mont RoucousFrance2.6 mg/L0.49 mg/L5.8Compare
18Callaway Blue Spring WaterUSA4.4 mg/L2.5 mg/L7Compare
19LevicoItaly9 mg/L1.8 mg/L6.3Compare
20Spa ReineBelgium5 mg/L2 mg/L6Compare

Harder, mineral-rich water: calcium 50 mg/L or more

Criterion: Still, unflavoured natural water with published calcium of 50 mg/L or more and TDS or dry residue of 600 mg/L or less. Highest calcium first.

Top 20 of 61 · per litre, as published
#WaterCalciumMagnesiumpHCompare
1GalvaninaItaly128.4 mg/L21.57 mg/L7.14Compare
2Ciego MonteroCuba112 mg/L3 mg/L—Compare
3PrealpiItaly105 mg/L99.3 mg/L6.9Compare
4PiervalFrance103 mg/L4.7 mg/L—Compare
5CereliaItaly102 mg/L10.8 mg/L7.1Compare
6VikosGreece101 mg/L1.54 mg/L7.5Compare
7KorpiGreece98.4 mg/L2.2 mg/L7.3Compare
8FrasassiItaly97.2 mg/L4.2 mg/L7.33Compare
9HildonUK (England)97 mg/L1.7 mg/L7.3Compare
10ChambonFrance96 mg/L6.1 mg/L—Compare
11VitasnellaItaly96 mg/L29 mg/L—Compare
12Saskia (Leißling)Germany95.4 mg/L21.5 mg/L7.2Compare
13Blue KeldUK (England)95 mg/L4.3 mg/L—Compare
14Sant AniolSpain91.9 mg/L17.5 mg/L—Compare
15Aqua VivaSerbia90 mg/L13 mg/L—Compare
16RajecSlovakia88.6 mg/L17.8 mg/L—Compare
17SorgesanaItaly88.5 mg/L10.8 mg/L7Compare
18Saskia (Wörth am Rhein)Germany87.4 mg/L15.5 mg/L7.6Compare
19StrathmoreUK (Scotland)87 mg/L15 mg/L—Compare
20Wenlock SpringUK (England)86.6 mg/L35.4 mg/L7.5Compare
Sources (40)

FAQ

Can I use bottled water in a fish tank?

You can, but it is rarely needed. Extension services treat dechlorinated tap water as normal. Distilled and purified waters need minerals added back; spring waters vary, so test GH, KH and pH first.

Values as published by each brand, per litre. Not medical advice.