One of the principles of permaculture is to look at things that would commonly be thought of as a waste product and instead, view it as a resource. You are always looking for the next best use out of everything. In our present day system, we pipe clean, potable water into our house. We use it to drink, to wash clothes, to take showers, to flush toilets and to water plants. After this initial use, we pipe the water, now called gray water (with the exception of the water from the toilet which is called black water) out of our house and into the sewage system. Within a permaculture system, you would look for other ways to use this grey water instead of letting it be taken away.
There are a couple of different options that involve using what is called a gray water system. These systems are what I'm currently researching. In most metropolitan areas, grey water systems are illegal or at least restricted and you should contact your local municipality to see what restrictions there are in your area. Eventually, when we move to our acreage, our house will be off the grid and we will reuse all of our grey water. I would like to begin some of the process in the house I live in now. I would like to capture the water from our washing machine and contain it in a barrel reservoir, to later use to irrigate my gardens.
If you have any desire to install a gray water system, or are even just interested in learning more, you absolutely need to get the book Create An Oasis with Greywater by Art Ludwig. What I am researching now is how to capture the water from our washing machine and save it in a barrel. I can later use this water to help water my garden. It is necessary to be careful what kinds of cleaners I use to wash our clothes because I don't want to be putting chemicals onto my plants. This goes right along with what I'd like to do any way because I'd like to be making my own soaps.
I'll keep you posted on how our project goes and give you some pictures of our progress. The big challenge will be to cut a hole in our laundry room and reroute the water outside the house to be stored. Our laundry room is on the second story from the back of the house, so, there will be some challenges. I highly recommend you get this book, check out your local library. You can also get lots more information from the Oasis website.