Questions about snaking the drain line for a Bosch SHU5305. Should I be able to snake all the way from the sink connection into the dishwasher or is there some type of backflow prevention or something similar that will inhibit me from reaching into the dishwasher?

You should contact a maintenance expert

Your sink drain is higher than your shower drain.
When water is going down the sink drain it hits a blockage with nowhere to go it backs up and it flows through the drain to your shower.
You have a blockage in your drain pipe T connecting your sink drain and the shower drain.
That's the only thing I can think of. You can try to snake it yourself or call a plumber.

You need to pull the plumbing under the sink to see if the trap is clogged. Snake after the trap.

Sounds like your sink drain trap or line is clogged. When the dishwasher drains, the sink drain can't keep up, the water backs up, then backs down the dishwasher drain line into the dishwasher. You may not notice the slow line when you run a little water into the sink, but with the amount of water coming from the dishwasher the problem is worse. You can try taking off the trap under the sink and making sure it's clear. If the problem is farther down the drain line, you can try snaking it yourself, or call a plumber. I don't recommend using Liquid Plumr or Drano because if those don't work, they leave the line full of caustic chemicals for the next person who works on it. That can be dangeerous.

Hi,

Blast water or air through it...

Here is a tip that I wrote that will help you with your dishwasher not draining problem...

Dishwasher Problems - Water will not drain out

heatman101

The dishwasher drain line that connects to the garbage disposal or pipe under the sink should be looped above the height of disposal or pipe to prevent
sink water from backflowing into dishwasher.

Most dishwashers have some form of internal backflow preventer inside the water sump assy..
Yours may be degraded or stuck open.

you need a longer snake had one on friday that wa about 40 feet out it took two trys to get it good luck

My model is actually a SHX46 but I was able to piece together some advice off of this site. This is what I did. I removed the toe plate and then I soaked up all the water that I could out of the white pan at the bottom. Then I unhooked the water supply line so that I could pull the dishwasher out. Once I got it out, I tipped it forward to drain out the rest of the water. I then unhooked the drain line that was connected to the disposal and cleaned it out with a "Snake line" I then hooked everything back up and it worked. Thanks so much for this website, I know it saved me a ton of $$$$$$$$$.

your dirty water backed up into the washer (which it shouldn't do) and probably clogged something in there,..i would recommend getting it flushed out somehow, not sure how,.....next time, your washer drain hose should go up under the sink as high as possible and then back down to drain,....this settup makes it hard for drain water to go back into washer,....it's instructed in any dishwasher manual

Hi You have a drain problem, Your house drain may be restricted the dish washer pumps out with more pressure then the water just falling down your sink.I would snake it or have a plumber clean out that drain...let me know if this helps krazytech