Hi John,
Margreet's advice is perfectly correct (thanks Margreet!), it's pretty
powerful stuff so should be started off slowly and gradually increased.
The labelling, specifying for external use only, is to get around EU
regulations concerning mineral waters and is the only way it can be
imported without going through rigorous testing and an even heftier
tax, apologies, should have pointed this out to you.
Sorry for the delay in answering, still catching up with my inbox...
Love,
Nicola