What is considered grey water vs. black water depends on the laws in your state, not necessarily on the quality of the discharge. Last year we finished a house where we installed a grey water tank that fills from everything but toilets and kitchen sink. We have a pump in the tank and can irrigate with the greywater (we're planting an orchard). (We also keep a bucket in our kitchen sink and water outdoor plants from it by hand -- this way we can control what goes into it.)
There are three things to avoid in your shower and laundry if you want the plants to continue to live long-term:
Sodium of any kind, chlorine, and borax (boron) -- these will all kill plants if they build up in the soil. It's the concentration in the soil that's bad, especially if you don't get much rain to help wash it away. Previous owners might have been lucky so far. Read labels. Baking Soda = sodium bicarbonate, not a good idea on a regular basis (although I do use a small amt to clean the tub ring). Basically almost ALL soaps, including Ivory and plant-based "eco" soaps, organic shampoos, and Tom's of Main toothpaste still use Sodium Lauryl Sulfate as the surfactant. I read labels for about two months after we moved in. We still brush our teeth with Tom's b/c of lack of alternatives.
We now use Dr. Bronner's castille soap for shampoo (1 cup castille to 1T melted coconut oil as a non-salt surfactant). I put the pump bottle under the shower spray as it's getting hot so it will re-melt the coconut oil and then just lightly shake the bottle before I wash. I've had great success with this shampoo. I no longer need conditioner or to wash my hair as often, so this offsets the extra cost over my old Suave standby. Every now and then I use dilute (1T vinegar to 1cup water) vinegar solution to get an extra hair conditioning.
I use vinegar and small amts of baking soda to clean all the sinks and tub (and toilets for that matter) -- they all work great -- way better than any "real" product I've ever used.
Ecos brand is the only brand of laundry detergent I've found that doesn't use the SodiumLS and states on its lable that it's grey-water safe. (They're zero carbon, too, which is a plus.) Costco sells it. I make sure I don't use more than the directions say. Our clothes are clean. For stains, I use Citrisolve -- it works, again follow directions, it can bleach a bit if you get overzealous like I did. We recently started using Dish Mate dish soap in the kitchen b/c it uses cocunut oil as its surfacant. I found all these things at my food co-op.
All grey water should be discharged **into** the soil, not on top of the soil. Mulched basin is the term -- essentially a depression or hole filled with organic material like woodchips or shred. Soil heals all wounds! When in the soil, composting away, trace amounts of fecal matter from any and all animals (mice, dogs, us) will be composted and turned into beautiful soil. If it goes into a mulched basin, then you don't need to worry about any bodily ucks at all!!
I haven't seen any research regarding soiled diapers, but personally, if the laundry greywater is going into a good mulched basin, I wouldn't worry about it. You wash other clothes in the same washing machine afterward. There's really not much left on the diaper, and presumably, your infant doesn't have round worms or other fecal-spread diseases.
I recommend any of the books by Art Ludwig and/or Brad Lancaster. Here's Lancaster's website:
http://www.harvestingrainwater.com/greywater-harvesting/greywater-compatible-soaps-and-detergents/ Ludwig addresses amounts of water discharge per sq ft of irrigation space, etc.
A bi-product of the label reading and research I did of these products and switching to greywater safe products is that we're no longer slathering all those EDTAs and other nasty carcingoens all over our skin! I really had no idea before.
Good luck and enjoy your greywater and your fruit!