Is my kitchen sink drain setup actually up to code?

Those accordion extensions are a major red flag beacuse they are illegal in almost every jurisdiction for a reason. The internal ridges catch grease, hair, and food particles, wich eventually rot and cause a nasty clog or a permanent smell. Beyond the flex pipe, you're likely looking at an **S-trap** configuration if the pipe goes straight down into the floor. S-traps are notorious for siphoning dry, which pulls the water seal out of the trap and allows sewer gases to vent directly into your kitchen.

You mentioned the dishwasher feeds into a Y-fitting, but check if that drain line has a **high loop**. If that hose just runs straight from the floor or the back of the cabinet into that fitting without being secured to the underside of the countertop first, you're going to get dirty sink water backing up into your dishwasher. It's a common oversight in DIY remodels that leads to "clean" dishes smelling like a swamp. Fixing this is manageable if you're handy, but you'll need to ditch the flexible junk for rigid PVC or polypropylene. If your drain pipe comes up through the floor rather than out of the wall, you need to install an Air Admittance Valve (AAV) to properly vent the sink and prevent that siphoning effect. You can buy a kit for this at any big-box store. Just make sure the AAV is mounted as high as possable under the sink cabinet.

The Y-fitting for the dishwasher shoud be a "dishwasher wye" tailpiece located above the P-trap. This ensures the dishwasher is protected by the same water seal as the sink. If the current Y-fitting is after the trap, you’re basically letting sewer gas into your dishwasher. It's a few hours of work and maybe fifty bucks in parts to avoid a major flood or a failed inspection later.

Spot on about the accordion junk. You should pick up an Oatey P-Trap Kit to replace it. I always use the Oatey brand for these because the washers actually seal and don't get brittle after a year. If you find out you've got an S-trap situation, grab an Oatey Sure-Vent Air Admittance Valve too. It’ll stop those gurgling noises and keep the sewer smell out of your kitchen. It’s a reliable way to fix the venting without a massive headache.

While you're at it, swap that Y-fitting for a Keeney K826-34 Double Sink Baffled Tee if you’ve got two bowls. The internal baffle is crucial beacuse it prevents wastewater from one side from shooting across into the other. For that dishwasher line, don't just loop it; use a 7/8 inch stainless hose clamp to secure it to a brass dishwasher tailpiece. Those plastic snap-on ones are garbage and always leak once the hot cycle hits. If your sink is deep, you might need a 1-1/2 inch slip joint extension tube to hit the drain height properly without straining the seals.

Don't forget to check those PEX shut-off valves while you're down there. Since the place sat empty, those rubber seals can get brittle. I've had 'em start leaking from the stem the second I finally turned 'em.

When you're puttin' in the new rigid stuff, don't go overboard with a wrench. Hand-tightening those plastic nuts is ussually enought, maybe just a tiny nudge with the pliers if it's still dripping. If you crank 'em too hard, you'll just crack the plastic and end up right back at the hardware store.

Oh man, I'm so pumped to see all these tips! I just bought my first set of tools and I'm ready to overhaul my whole guest bath after I finish the kitchen sink. Since you guys mentioned the PEX lines, I've been dying to know—what’s the deal with the diffrent crimping tools? I saw a battery-powered one that looked awesome but it was like $400! Is it actualy better for a newbie, or should I just stick to the manual ones and get a workout? I'm worried about not having enough arm strength to seal them right!

Quick update—I checked and it’s definately an S-trap, so I’m grabbing the Oatey kit and the Sure-Vent AAV. One thing though: when I tried the PEX shut-off valves like someone suggested, the cold side started dripping from the handle immediatly. Since the place sat empty, shold I just replace the whole valve assembly or is there a way to just fix that brittle seal?