If you still think a peat flavour might have come from the water, read this:
situated in the immediate vicinity of Holyrood Palace. The fame of Edinburgh ale, of which they are by far the largest makers, is known all over the world. The trade of this firm has been a steadily increasing one. The superiority of their ale is partly owing to the adoption of all mechanical and other improvements, and also to the chemical properties of the water, of which, by sinking to an immense depth, they get an abundant supply. Professor Dr. George Wilson and Dr. Maclagan, having made several analyses of the water, found it free from colour, taste, and odour, and after having subjected it to the most rigid chemical tests, scarcely found a single trace of organic matter. Its most abundant properties are carbonate of lime and magnesia, sulphate of lime and soda, and chloride of sodium. Their ales are exported to almost all parts of the world, where they have established agencies, and this branch of their trade has extensive premises entirely devoted to it situated at a short distance from their Brewery. They have, besides, large maltings in other parts of the city. The Pale or India Ale, so strongly recommended by the medical faculty, is extensively brewed by them, precisely on the same principles as at Burton, and as it is rising daily in reputation, has every likelihood, like their other ales, of gaining a world-wide fame."
"The official illustrated guide to the Lancaster and Carlisle, Edinburgh and Glasgow and Caledonian Railways" by George S. Measom, 1859 , page 198.
So Younger's brewing water was "free from colour, taste, and odour" and contained "scarcely found a single trace of organic matter". Note also that they were the largest producer of Edinburgh Ale and they were big exporters.
A peaty taste from the water? Don't make me laugh.