I have been doing BORAX ( 20 MUle team) from grocery store. It is 99.5% pure. I add like 1/4 tsp in my 1 liter water. and drink that.
I do it like 2-3 times a week.
I hope u re-mineralise your water with a good quality sea-salt. Drinking de-mineralized water is not a good idea, as it will deplete the body of essential buffers..I was thinking of buying a distiller, but have now changed my mind.