btw - I'm not sure if 'grey' water is the appropriate term for the a/c water. This is the water that the air conditioner dehumidifying unit outputs. We get about 15 gal/day lately (running at 80F) if we're home all day, a little less when not.

I honestly don't know how the process works, to say what's in the water. WE have been using it on our trees for a couple of years.

The bath water we've only used a couple of times so far - no pump, we just use a bucket to carry a few gallons outside.

The AC water is nothing more than condensation, like rain. The soap in bath water is nothing to be concerned about unless you use a whole bar each bath. The soap will act a surfactant so the water will hold to soil particles longer. Which means the water will be available to the plant longer.

also check your local codes. some don't allow use of grey water (although people do anyway). usually i see laundry water being used in the garden. i know some soaps are better than others - some you probably wouldn't want to use on edible plants. i've seen diagrams of systems where you put grey water through a series of rock/sand before using it too. i found quite a few links awhile ago because i was going to try and figure something out to use more grey water too. it's a good way to go.

It's usually recommended you alternate 2x gray water to 1x fresh water, due to salt build-up using the gray water. Otherwise, you can put in a DIY filtering system. Here are some websites with info you can use for research:

Greywater sites:
http://en.wikipedia.org/wiki/Reclaimed_water
http://www.greywaterguerrillas.com/
http://www.greywater.com/
http://www.ecologycenter.org/ecohouse/greywater.html

The best solution is rainwater harvesting from your roof, assuming you live in a state where this is allowed (believe it or not, in some states, such as Utah, it is NOT). However, you need room to place (and hide) a fairly large cistern on a concrete pad, about 9-12' around and 5-6' high, depending on storage size needed. In an average rainy season you can harvest 15,000 - 18,000 gallons of water for storage. Note that there may be additional costs to install new gutters for easy feeding into the cistern. For some houses it's easy; for others it's not, so an individual analysis is needed for the appropriate solution to each unique house/site.

Rainwater harvesting:
http://en.wikipedia.org/wiki/Rainwater_harvesting

Rainwater storage tanks:
http://www.plastic-mart.com/class.php?cat=9
http://www.ntotank.com/?gclid=CMKatN68vpMCFRGiiQodI1wbfQ
http://www.loomistank.com/

This is all info I got from a local vendor who is installing a filtered gray water system for us in the next month. Hope this helps others!