Mark is 100% right on the money - take his advice. No need to repeat it, just a nod of confirmation.
Some folks just can't stand the little jolt/shock when they touch the DC hose to skin. If that is your case, then sure, thats a good enough reason to work to minimize it, but forget about grounding it. I have no idea why - but my DC used to shock me pretty reliably but I replumbed it - same material, just more of it, and it stopped completly. I'm sure there is an engineering explanation for it, but I was just happy to not get shocked any longer.