I'm beginning the process of installing a dishwasher in our 55 year old house. It cannot be placed next to the sink, but all the lines, including electric are located right underneath the floor where the dishwasher will go. So, through the floor I will go.

1) Must I run the electric cable and the plumbing pipes through separate holes through the floor or can everybody share? (Water and electricity side by side--sounds risky.)

2) Once under the floor, I need to connect to a 2" PVC drain which comes from the sink on its way to the main. How to create the air gap so that I won't get stuff backwashing up from the sink? Can I loop the drain hose up above the PVC (making my own J trap) before attaching to the PVC? Since I will be selling the house someday, I don't want to be too far from code.

Hey Goat,
1) Must I run the electric cable and the plumbing pipes through separate holes through the floor or can everybody share? (Water and electricity side by side--sounds risky.)
To be safe I would make separate holes for the water and power.

2) Once under the floor, I need to connect to a 2" PVC drain which comes from the sink on its way to the main. How to create the air gap so that I won't get stuff backwashing up from the sink? Can I loop the drain hose up above the PVC (making my own J trap) before attaching to the PVC?

You MAY NOT connect directly to a drainage line with out a "P" trap and vent. This would open a direct line from the sewer into your home. The loop you describe is not a "P" trap but a drip loop, (this takes the place of a air gap). More about that later.
How far will the Dishwasher set from the sink? Unless you want to get into installing a new drain,trap and a vent out the roof you'll run the DW discharge this way.
First make sure the hose is long enough to reach the sink. Next loop the hose all the way up as high as it will go and secure it with a pipe strap. Now run the hose over to the garbage disposal and connect it to the male opening with a hose clamp. (A word of caution, punch out the insert before connecting) If you don't have a disposal then purchase a branch tail piece and replace the existing tail piece and connect to that. Sound like a plan?
Regards, Tom

Thank you for keeping me from making a major mistake! Since I do not want to rip up any existing cabinets, the dishwasher drain line would be well over 12 feet long before it gets to the sink. I'm afraid the pump in your average cheapo dishwasher may not have the oomph to make it.

However, many years back, when I wanted a washing machine in the basement, a licensed plumber did install the Ptrap and vent you describe. He tapped right into the main sewer line. Now I'm thinking of running the dishwasher drain to it as well. Since it is downhill of where the dishwasher drain will appear under the kitchen floor, gravity will assist.

By the way, I tried your tip about unclogging the "siphon hole" in the toilet bowl. (I put on a disposable latex glove.) The toilet has NEVER flushed so well. Thank you thank you!

" Many years back, when I wanted a washing machine in the basement, a licensed plumber did install the Ptrap and vent you describe. He tapped right into the main sewer line. Now I'm thinking of running the dishwasher drain to it as well. Since it is downhill of where the dishwasher drain will appear under the kitchen floor, gravity will assist."

That works for me. Just loop the hose up as high as you can under the cabinert for a air gap and to prevrent backflow. Once looped up, secure the hose with a pipe strap.

"By the way, I tried your tip about unclogging the "siphon hole" in the toilet bowl. (I put on a disposable latex glove.) The toilet has NEVER flushed so well. Thank you thank you!"

You're welcome, welcome! Regards, Tom