This is very interesting, Jens
The zigzag is a common Indian pattern indeed. It is also called Chevron pattern. There are vast examples of Chevron pattern including textiles, tiles, architecture, metalwork... in a variety of cultures: Persian, Ottoman, etc. Note the famous Indian Chevron pattern-weld pattern, for example. Presumably, it is a symbol of water, stemming from the double chevron hieroglyph of the old Egyptian civilization!
Here is another sample of Chevron/Zigzag decorations on Indian fittings, I think of late 19th Century:
|