This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
The contamination of the water by contact with metals has been a source of considerable anxiety to the manufacturers of carbonated waters. Contact with lead or any other easily oxidized metal must be avoided. There is no difficulty in securing this object by a coating of tin or silver, but when particles of metal are introduced by attrition it is not so easy to suggest a remedy. We occasionally hear of metallic impregnations in water, especially those containing citric or tartaric acid, and we would just suggest that before we attribute this to defects in the mechanical appliances, it will be better to see if the materials are free from fault. These acids are usually crystallized in lead-lined vessels, and are more frequently impregnated with this metal than most people are aware of.
Injury to lead by contact with lime is well worthy of consideration. It is extraordinary that this effect should have been so entirely ignored, as it has long been known that water, impregnated with lime, when passed through leaden pipes, becomes extremely injurious, simply from its taking up by some chemical process a certain amount of the lead, whereas the limewater itself would not be dangerous. Prof. Angel, in the National Bottlers' Gazette, says on this subject:
"It is of the utmost importance to know whether water used for drinking purposes contains lead. A little gradually taken into the system does not pass off, but accumulates until the quantity is sufficient to result in bad if not fatal consequences. Since the poison is so insidious in its action, one does not receive warning until it is too late.
"If a piece of bright lead is exposed to moist air, it soon becomes tarnished from the formation of a thin film of protoxide of lead, produced by the action of atmospheric oxygen. If this piece of lead should be now placed in water perfectly pure and free from air, the oxide would dissolve, leaving the metal bright, after which there would be no further action, since no more oxide could form. But if air had access to the water, the twofold action of oxidation and solution would continue together, and the surface of the metal would remain more or less bright, 4 according as the oxide is formed faster or slower than it can dissolve. If some sulphate or carbonate be now added to the water, these salts immediately react with the oxide to form on the metal an insoluble coating of carbonate or sulphate of lead, which, being insoluble in water, prevents further action. These facts explain the behavior of natural waters towards lead. In the first place the protoxide of lead is always formed, which dissolves if the water does not contain the necessary saline constituents to prevent it. Water that contains any salt of lime or magnesia in excess is called hard water. Generally these bases are present in the form of carbonates or sulphates; hence the commonly accepted view, that hard water does not act on lead. But here is an error that must be guarded against. The water fails to act on lead, not because it is hard, but because it contains sulphates or carbonates. A soft water containing sulphates or carbonates of the alkalies has no action on lead. On the other hand, a water hard from the presence of carbonate of lime or magnesia frequently acts on lead freely, because the same acid that dissolves them and explains their presence, also dissolves carbonate of lead. Hence it is plain that some very hard waters, highly charged with carbonic acid, readily act on lead. The decomposition of organic matter produces carbonic acid; consequently the presence of organic matter facilitates the action of water on lead. Nitrates dissolve lead freely. The metal should not be used in waters containing them. Sulphates in water protect lead most, since the sulphate of lead is insoluble in water and acids. Carbonates are next in order. The carbonate of lead is insoluble in water, but soluble in acids - even the weak carbonic acid.
"Water that is hard is so, generally, from the presence of sulphates or carbonates of lime and magnesia, so that ordinarily it might be considered safe to use lead in hard water. But since there are exceptions both against hard water and in favor of soft water, the only safe way is to test every water in which lead is used.
"Another rough method is, to observe whether the surface of lead which has been in water for some time is bright and shining, like newly cut metal, or is dull in color, very gray, or brownish. Too much reliance should not be placed upon the color, for the oxide may not dissolve fast enough to keep the metal bright, and yet not much may dissolve. However, if the surface is bright and clear the evidence is decisive; for it would not be if the oxide did not dissolve".
It is best to have the pipes through which the water runs, of iron or of pure solid tin - lead should be entirely dispensed with.
The storage cisterns should be of wood, or, best of all, of slate. If 1/10 of a grain of lead per gallon is present in water, it is dangerous for drinking and should be rejected.