In article , Calvin wrote:
I'm not mad and I don't want a Darwin Award. There, that's set the
ground rules now to the question.

We have a Sodastream which is fantastic - provided we can get hold of
replacement CO2 cylinders we can have sparkling water in unlimited
quantities without the hassle of dragging heavy bottles of water home
from the shops and the associated waste packaging.
Sadly Sodastream as a company are a disaster to deal with.
[...]
Alternatively, and much more uk.d-i-y, any thoughts on the
practicalities and dangers of a homemade system.

Have a look at http://www.truetex.com/carbonation.htm