How to sort out this drain?

[jferello]

Hey all,

Looking at the picture below, you can see that I have a horizontal 2" drain pipe in my basement. Right now I have a water softener, iron filter and washer all jammed into the same pipe. I did not do this, the previous owner did.

First question, why do the two drain lines for the water softener and iron filter need to be raised up above the pipe?

Second question, I want to spread these out. Would I just extend the 2" horizontal pipe with 1 P-trap and then have 3 vertical runs about every foot?

Thanks,
Justin

 

[Reach4]

The reasoning for an air gap is in case there becomes a vacuum on the potable water lines develops a vacuum. The valving for the softener creates a path. Then the sewer line is blocked and a pipe dipped below the standpipe level sucks up water and into the potable water supply.

The reasoning that different rules apply to the the washer appears that the drum fits in a tub that is vented at the top, and water comes in from above that. The washer cannot pass a vacuum on to the sewer line.