Under Sink Hookup vs. Dedicated Drain Line: Which Is Better for Dishwashers?

I get the “if it ain’t broke, don’t fix it” logic, but I’ve had a high loop fail once when a tenant didn’t notice a slow clog.

“if you’re on top of maintenance and don’t let gunk pile up, high loop does the job just fine.”

I hear you—had a rental where the high loop “did its job” right up until it didn’t. Tenant called me about a funky smell, and sure enough, water everywhere under the sink. Air gaps might look like little robots sitting on your counter, but I’ll take weird over water damage any day. Sometimes paranoia just means you’ve learned from experience...

Had a similar issue in one of my units—high loop was textbook, but it still let water back up during a clog. Here’s what’s worked for me over the years:

1. Air gap on the counter, even if it’s ugly. It’s code in a lot of places for a reason.
2. Make sure the drain line from the dishwasher is routed as high as possible under the sink before it drops.
3. Regularly check for slow drains—if the sink’s backing up, the dishwasher’s next.

Honestly, air gaps save headaches. Not pretty, but neither is replacing cabinets...

I hear you on the air gap—ugly, but it works. I’ve seen high loops fail plenty when the main drain clogs. Out of curiosity, has anyone here actually run a dedicated drain line for a dishwasher? Wondering if that’s ever worth the hassle compared to the usual under-sink hookup.

I’ve actually run a dedicated drain for a couple of clients, but honestly, it’s pretty rare. Most folks stick with the under-sink hookup because it’s just simpler and cheaper. Dedicated lines can help if you’ve got chronic clogging issues or a weird kitchen layout, but for most setups, it’s overkill. Air gaps aren’t pretty, but they’re code in a lot of places and do the job. High loops are hit or miss—seen them fail too when the main gets backed up. Unless you’re remodeling anyway, I’d say the hassle usually isn’t worth it.