Can I divert my shower and tub drain to yard watering?

yes. We do that now. It’s called a gray water system

Gray water systems are illegal in some cities due to environmental concerns over untreated waste water. Be sure to check local laws before investing in a gray water system.

Yes! There is a group in Oakland CA called the Greywater Guerillas that teaches people how to do this. They also have a book called Dam Nation: Dispatches from the Water Underground.

This interview from Sierra Magazine tells you more about them and what they do:
http://www.sierraclub.org/sierra/200711/one_small_step.asp

here’s a link directly about creating your own greywater system
http://greywaterguerrillas.com/greywater.html

Of course, evander also raises a good point about making sure you are not releasing untreated waste water into your yard. If you are going to create a greywater system you will have to switch to all natural, all biodegradable soaps, because you don’t want to pour anything toxic into your yard. The simplest and easiest way to recycle water in your house without hiring a plumber is to unscrew the draining pipe under your sink and put a bucket there instead, so that the sink drains into the bucket. Then when the bucket is full you can use it to flush your toilet by pouring that water into your toilet tank. That way you aren’t using perfectly clean water to flush your toilet.

I believe soap as a substance/compound is naturally biodegradable, but it is true you want to be careful about releasing chemicals into the environment. I’ve done some research (and know a couple of people who have experienced chemical poisoning), so if you go this route, please be aware that there are plenty of chemicals out there that are bad for you and the environment.

That said, having studied plants, I would be wary about watering with soapy water. A soap solution may be sprayed on tolerant plants in order to combat insects, but I imagine some plants could be sensitive to soap in the soil. Some are more sensitive than others to different soil conditions.

I did a little Googling and found a school science project where the plants actually grew better with soapy water, and another ‘water miser’ link that advised to not water indoor plants with soap water. I guess my conclusion remains the same, that it’s possible, but I would see how your plants react to it before redoing your plumbing system.

According to a couple of articles I’ve read, as long as I filter the water through a nice big pile of mulch, any soap shouldn’t be an issue. My washer uses high efficiency soap, and it seems like my tub/shower water is barely contaminated since most of it runs down the drain with just my personal skin flakes in it. I wouldn’t want to do this with the rest of the house (kitchen sink, dishwasher, etc).

Thanks for all of the input!