I cannot use my tap. It tests ridiculous Ppms 450+and ph is 10. I'm not sure what the deal is but I'm not risking poisoning my soil that cost me $300 and kill my plants that will save me $1000+ per plant on medicine . I buy my spring water $1.15 per gallon store bought. I've found for my area ice mountain spring water to be the best ph 7.0 with 50ppms. I use the single gallons for presoak, spraying, and small sips. On a small scale I would use only ice mountain. But after about 3-4 weeks 10-20 plants can start to drink alot of water. So I switch to RO that I get from a self serve Culligan machine for $1.25 for 5 gallons. I try to buy 30 gallons of spring water and fill 15 5 gallon jugs of RO to start every grow.I buy more RO as needed. Long answer to a short question. But when your water sucks it can get complicated. I'm 20miles from the nearest store. So I've got to stock as much as I can.