If you do have a "downstream injector" then yes you can inject just about any non-corrosive chemical and be OK. I would use diluted laundry detergent instead of dish soap based on my experience with cleaning paint brushes and such.

I have found the special housewash solution to be not very soapy. Doesn't work much better than just water.

Please note that I'm referring to washing a house or deck, not the car.

I have also found that some driveway and concrete cleaners for the washer or directly applied are less soapy than I prefer. ........weed cutter: do you have a water to laundry detergent mix?

Thanks for the replies, I'm going to try different mixtures from now on and will post back results...I'm far too cheap to be buying the correct stuff.

Hey, I have been waiting 6 years for the follow-up post... :) Any feedback?

I assume the "downstream" means after the water passes through the pump?

I washed our vinyl siding with a bleach and Dawn detergent mixture in the tank. Worked just as well as commercial mixes that you have to add the bleach to anyway. And my pressure washer injects the mixture downstream as well.

Just did simple green and laundry soap worked awesome!

What if I use cascade soap? Wouldn’t it work better since cut grease and has enzymes that break down organic matter? And has oxy cleaner?