RO Water - zero alkalinity

[Dave S]

I just bought my first batch of RO water from a nearby aquatic centre. £10.98 for a robust container and the first 25l free. and £2.50 per 25l thereafter. Now you cannot say fairer than that.

Anyway I took a sample today to measure the alkalinity and I got zero. This surprised me a little as I was expecting some alkalinity, Martin's default is 13 mg/l. So, I am going to assume that the rest of the mineral content is going to be zero, or as near as damn it also. Thus I will treat it as distilled in my calculations.

Has anyone else got this result from their RO water?

[Aleman]

If it was RO water from a good well maintained unit I would expect minimal alkalinity . . . perhaps a maximum of 1% of the original water . . . if it has a deionising resin following the membrane then it should be zero.

Not a bad price considering the unit I am putting together (if I finally click the buy button) is around 700 quid!

[Jeltz]

RO water is typically >95% pure. The membrane that filters the water will only let some of the very smallest particles through so I would have been surprised if it hadn't had 0 Alkalinity.

[Dave S]

Excellent, thanks chaps. I'll treat as if distilled then.