Intriguing idea, and not a still in sight, I wonder how long it lasts? It doesn't say to refrigerate it but I guess it would help it last for longer? Love the idea of an elderflower version, I'll try that when I get the elderflowers when its dry, also want to make some elderflower tincture.
If you want a pink looking rose water use the red range of roses and it goes without saying, the greater the intensity of perfume in the rose, the more aromatic your water will be. Not sure I'll have enough roses to make this though, when my roses appear I want to make rose vinegar, wine and cordial. Mind you the wild roses are out now, nothing stopping me getting a few pints of these when they're dry to try out the rose water.
I often add commercial culinary rose water or orange flower water to cake mixes and I make rose geranium castor sugar, which works wonderfully to transform a plain sponge cake into something out of this world. In her Cooking With Flowers book, Jekka McVicar, has a Rose Sponge with rose water icing and crystallised rose petals recipe, which contains rose water, it looks amazing and will be on the list of things to try this year! I'll give the elderflower water a go, thanks for the tip Sarah 
Debs