It may be taken as characteristic of Australian plumbing work that much less lead is used than in Britain, the excessive and sudden changes of temperature being most destructive to this material.

In place of lead, galvanised iron has come into general use even in good class work. For gutters, heavy gauge galvanised, specially flatted sheet iron, double riveted and double soldered at all jointings, turned up against walls and well under roof coverings, and left free for expansion and contraction, is generally found to be the best.

Lead wastes, too, are much inclined to creep, and if carried along walls often sag in swag-like loops where exposed to high temperatures. Galvanised welded tubing, glass-enamelled inside, is therefore largely used for soil pipes, wastes, etc., and brass and iron are growing in favour for sanitary traps and small fitments.

For eaves spoutings, rain-water pipes, roof ventilators, and for many other general purposes in outside building, the practice is for galvanised sheet iron to be used.

In sanitary plumbing, Australia has presented some interesting practice. With extensive modern sewerage systems in Sydney, Melbourne, Adelaide, and smaller systems in other cities, the peculiar needs of climate have found marked expression in the work, and for data the student would do well to study the systems of working adopted by the authorities controlling these works.

Though lacking in aesthetic qualities, galvanised iron as a roof covering has been a most practical boon to the country settlers of Australia, where the all-important problem of water supply is ever present.

This material has therefore become the general roof material in the country districts, and is in its corrugated form largely imported, the general lengths being from 5 to 10 feet, with 26 and 24 as general gauges. The fixing is generally by means of galvanised screws through each alternate corrugation to under-side battens about 24 to 30 inches apart. End lap is from 6 to 9 inches, according to pitch of roof, with 1 1/2-inch corrugation side lap. Hips, ridges, and valleys are all made of galvanised sheet iron, and are riveted and soldered together in position, the whole making a light, durable, and weather-tight covering.