Jermaine Jackson -- Using His 84-Year Old Mother to Pimp Water Company

Jermaine Jackson doesn't need a hot bikini model to promote his new water company -- 'cause the Jackson 5 singer has his 84-year old mother to do the job.

Jermaine's company, Vita Water had a media event yesterday at Whole Foods in Tarzana ... and for some reason he brought Katherine Jackson along to help shill the drinks.

1) Katherine is too old to be posing for photo opps and handing out free samples.

2) Isn't she supposed to be watching MJ's kids?!?