The key difference between an enema and irrigation is how the water gets back out of the pouch. Irrigation sucks the water (and suspended material) back out, whereas an enema presumes the pouch can empty normally once the pouch contains a fluid suspension instead of solids. If you’re able to empty your pouch after squirting in tap water then irrigation is unnecessary.
But: why did the enema take 30 minutes? Pain? Fear? If your anal sphincter is too tight to comfortably insert an enema tip then you may have your diagnosis. You can add extra KY jelly to the tip, if the extra lubrication helps.
If you aren’t drinking enough water then you will likely end up in trouble (or may already be in trouble). Have you taken some time to think through why you aren’t getting enough? This is worth getting creative about, if that helps you - flavors, containers, mind-set, whatever. I’m confident that the work-up you’re facing is harder than consuming more fluid. I like psyllium, but it’s only a good idea if there’s enough fluid to go along with it.
Good luck, my friend. Go have a glass of water, or V8, or something.