[IndianAstronaut]

Where does the average person find RO water?

[HeyLaughingBoy]

Go to your local aquarium/tropical fish dealer and ask. They'll be able to list pretty much all the providers within a reasonable driving range.

Also lots of cities/towns have RO water providers that will sell anywhere from single gallons to thousands.

source: used to be a marine aquarium hobbyist and bought thousands of gallons of RO water to make seawater.

[ngoede]

Some grocery stores and walmart's have RO water machines outside their stores also. However, if you choose to use those it would be good to invest in a tester as they do not always change the filters on schedule.

[ketralnis]

Any drug store will have distilled water