Hearty good wishes to all.
A quick question, is there any reason I can’t use rainwater to make sun and moon water? I live in a part of the world where we get rain constantly and I’ve collected quite a few bottles including hail water, storm water etc. I filter those waters through a muslin cloth and then bottle with intention. Would love to hear any suggestions regarding this.
Thanks in advance
GeminiBen
Terrific Tuesday GeminiBen,
Well, I would LOVE to say, "Absolutely, Yes, use it"…However, with all the pollution in the air, I would not suggest ingesting it. I make sun and moon water daily, but I do use bottled water.
That said, there is much, you can do with rainwater. Bless/consecrate it however you wish, then you can use it to water your plants, mix it with a disinfectant spray bottle and you have a powerful cleanser for the home (powerful both the disinfectant, and the magickal powers too).
I am sure you can find other ways to use it too. Use it to wash your face or brush or teeth. Endless opportunities. A small spray bottle to use on your hair? I have a bottle with blessed oil and water. I don’t have rainwater, because I am here in Vegas, we are lucky to get 2-3 inches of rain per year; but I have blessed oil in with the water.
So, see…many, many ways to use it. I drink my daily sun/moon waters, so I use bottled water. But there are many ways you will be able to use rainwater in your practice.
Lady Gene 
I agree with Lady Gene, by all means gather rainwater and make sun & moon water with it.
Just don’t drink it. There’s plenty of other uses, as Lady Gene explains.
Last winter, I collected the top layer of snow in my yard after new & full moons, brought it in.
It was not all that clean, I’d never drink it. I put out my clear (not opaque) Alkali water bottles
in sun & moon for drinking purposes, and still use that collected snow for ritual purposes.
Yup, Indeedy
A good question!
Lady Gene and Sedim have said what I would say, but I will note that the energy of storm water, hail, snow, and sleet are very different from a gentle spring rain. Just keep that in mind if you use it in spells.
In my new practice I don’t use water… we use milk instead and the process is a bit different. 
Just out of curiosity, is there any particular source concerns?
Goat milk Vs. cow milk? pasteurized Vs. raw? Grass fed Vs. feed fed?
It should be cow’s milk, (but if you’re lactose intolerant I suppose you could experiment with substitutes) and the rest is kind of up to availability.
Organic Pasture-fed raw whole milk is the ideal - you want milk that’s not too processed and with low contamination. I can’t get raw milk where I live, so I just get pasture-fed organic whole milk. It’s still incredible! 
Thank you Lady-Gene,
Very helpful indeed. You live in vegas and only get 2 to 3 inches a year. I live in the highlands of Scotland and we can get 2 to 3 inches of rain in a day. I’ll send you some over. 
Kindest regards
Thank you everyone for your helpful advice it is much appreciated
Kindest regards.