Title: Under Sink Hookup vs. Dedicated Drain Line: Which Is Better for Dishwashers?
But here’s where I get stuck: are air gaps really necessary if you’re running a high loop under the sink? I’ve heard conflicting things from plumbers—some say the high loop does basically the same job, others swear by the air gap for backflow prevention.
You’re not alone—this comes up all the time. The high loop trick is definitely better than nothing, and in a lot of places outside California, it’s totally standard. But technically, the air gap is the only method that *guarantees* you won’t get dirty water siphoning back into your dishwasher. The high loop just makes it harder for that to happen, but it’s not foolproof. I’ve seen a couple of gnarly situations where a clogged sink or disposal caused some pretty gross stuff to back up into the dishwasher because there was no air gap. Not super common, but when it happens, it’s memorable (and not in a good way).
As for code, yeah—California and a few other states are strict about requiring air gaps. If you’re somewhere that doesn’t require it, you can probably get away with just the high loop, but if you ever have a big backup or sell your house, it could come up.
On the drain hookup, I hear you about the convenience of running it to the disposal. That’s what most people do, and honestly, it works fine as long as you keep the disposal clear. The dedicated drain line is nice in theory, but unless you’re dealing with constant clogs or weird smells, it’s probably overkill for most setups. I’ve only seen a handful of cases where someone regretted not having a dedicated line, and usually it was because their disposal was already prone to clogging.
If you’re not having issues now, you’re probably good. But if you ever notice water sitting in the bottom of your dishwasher or start getting funky smells, it might be worth checking for partial clogs or considering an air gap. Otherwise, I wouldn’t stress too much—most folks never notice a difference unless something goes sideways.
Yeah, I get where you’re coming from. I used to think the high loop was enough too, until I had to clean out a dishwasher that got hit with a nasty backup. Not fun. Air gaps look kinda weird on the sink, but honestly, they’re like cheap insurance. On the hookup side, I’ve seen disposals clog up and send gunk back into the dishwasher—usually after someone dumps a whole plate of pasta down there. If your setup’s working and you don’t mind the occasional maintenance, you’re probably fine, but man... when things go wrong, they really go wrong.
