A recent study in NSW by the Australian Government’ National Measurement Institute concluded an on running dilemma for industrial battery owners; should I be using purified water to top my batteries or can I get away with normal tap water?
Well, that depends on the amount of impurities there are in tap water. When a cell gasses the water evaporates and escapes. Solids within the water cannot evaporate and simply fall to the bottom of the battery.
To replace the water that has evaporated more water must be added, and with it comes a new batch of dissolved impurities which fall to the bottom of the battery when the water dissolves.
This continual process builds deposits of impurities in the bottom of battery and the more dissolved impurities there are in the water the faster the deposits increase and the battery's life shortens.
The prevalent dissolved solid in tap water is calcium or calcium carbonate, which neutralises the acid resulting in lower battery voltages and causes short circuits.
Total Dissolved Solids is the measurement of the quantity of a solid dissolved in water in parts per million. The National Measurement Institute measured the TDS levels in tap water around Sydney.
It found that the highest reading to be at Padstow at 110 ppm and the lowest reading was 76 ppm in Homebush. A reading of 110 ppm is considered of average quality in the US and Europe where battery companies will not warrant batteries unless the water used to fill has a purity level below 50 ppm.
So undoubtedly the answer to the question, is tap water suitable for battery topping? Is an unequivocal No.
The caveat is of course the cost, and subsequent storage of purified water. Fortunately there are now deionisers available from the more progressive battery dealers that will produce battery quality water for a mere 15 cents a litre.
For further information contact Chris Parkinson at Philadelphia Scientific .