Even pure waters, however, such as that of Loch Katrine (which forms the Glasgow supply), act so slowly, at least on such lead pipes as have already been in use for some time, that there is no danger in using short lead service pipes even for them, if the taps are being constantly used.
Lochs Lomond, Katrine and Lubnaig in the southern Highlands, and Lochs Maree and More in the north, are conspicuous examples.
Of natural lakes in Great Britain raised above their ordinary levels that the upper portions may be utilized as reservoirs, Loch Katrine supplying Glasgow is well known.
Since 1885, when the duke of Montrose constructed a road over the eastern shoulder of Craigmore to join the older road at the entrance of the Trossachs pass, Aberfoyle has become the alternative route to the Trossachs and Loch Katrine.