Some people rely on their washing machine's internal pump to pump laundry greywater out to the garden, but this is not recommended. Washing machine pumps are designed to pump water no further than the laundry trough.
My DIY solution is incredibly simple. To collect the used water I simply put the plug in the laundry trough, and place the outlet hose from the washing machine into the trough rather than down the drain hole at the back of the trough. I bought a basic sump pump (about $120), and this sits in the laundry trough. Details of this pump are given under Fig 8 on the Big Bucket Details page. I already had a round mesh filter (about 25cm diameter) from the top of an old water tank. This sits partly on the edge of the trough and partly on the top of the pump, and the machine outlet hose is positioned such that the used water passes through this mesh (to filter out lint) as it runs into the trough. I used this filter because I happened to have it, but an old sock or stocking tied to the end of the outlet hose would probably do the job just as well (or better).
Once a load of washing is finished, I connect the hose from the pump outlet to a greywater hose just outside the laundry door. I then switch the sump pump on. The water flows through the greywater hose to the front garden and into whichever one of my mulch-filled trenches the hose is poked into that day. (The mulch-filled trench method of distributing greywater is described on this page.)
The only things I need to do are connect and disconnect the hose at the laundry door after each load of washing, and clean the lint out of the filter about once per week. If your house layout permits, you could have your pump outlet connected to a thru-wall fitting, and have the hose to the garden permanently connected to the other end of the thru-wall fitting outside the house.
It is not that long since I wrote this post, but already I have changed the way I deal with my laundry greywater! This was mainly because of changes I made in my garden, but also partly because I was getting a little sick of having the hose from the pump outlet coiled up on the laundry floor. Rather than writing a new post or changing what I've said above, I'll simply give the information about the setup I am now using in this "stop press" - after all, both setups are perfectly viable alternatives.
Firstly, I'm no longer using the mulch-filled trenches described above because I now have raised planter boxes in that area of the garden. In order to get the laundry greywater high enough to flow into those beds I constructed the splitter box described here. Previously the greywater hose from the laundry just ran along at ground level between the laundry and front garden, but I now needed that hose to be raised sufficiently for the water to run into the splitter box.
Previously, I had not bothered to use a thru-wall fitting in my laundry because there is a door right next to the laundry trough, but the simplest way of getting the height I now needed was to take the outlet hose from the sump pump through the wall above the laundry trough. (See Fig. 2a to 2d on the Big Bucket details page for close-up images of options for thru-wall fittings). This is what the corner of my laundry looks like now:
To avoid the sagging that happens with elevated hoses, I decided to use rigid PVC pipes rather than greywater hose to take the water from the thru-wall fitting, along the house under the eaves, and to the splitter box in the front garden:
Here is a close-up of the thru-wall fitting plus screw-on barbed connector on the outside wall of the laundry:
I used a masonry bit, the hammer drill setting of my electric drill, and its highest speed to drill a 20mm diameter hole through the brick to insert the 30cm long threaded pipe for this thru-wall fitting. This was NOT easy - especially since I only had a 10mm masonry bit to drill a 20mm hole! Even so, now that it is done I think it was well worth the effort. Now, each time I wash the clothes, all I need to do to automatically water those raised planter boxes is switch on the pump, and then switch it off again once the laundry trough is empty.
Laundry powders and liquids...
There is an enormous amount of information about the effect of laundry products when using greywater on gardens at the Lanfax Labs laundry information website. It explains what factors need to be considered, and gives test results for a large number of commercial powders and liquids. The good news is that a reasonable number of readily available laundry powders, and almost all laundry liquids, are suitable when reusing laundry water in the garden. Select either powders or liquids from the left column of the Lanfax web page to find details of the contents of specific products.
Health regulations state that used dishwashing water should not be used as greywater in the garden due to the food particles and grease it is likely to contain. However, I seem to use a lot of water for other purposes in the kitchen, such as washing vegetables, rinsing my tea cup, and washing my hands countless times per day. All those things I do over an ordinary plastic bucket that I keep sitting in the kitchen sink.
I don't have any fancy system for delivering that greywater to the garden. Like most people, I simply carry the bucket outside and use it to water the pot plants and the section of garden closest to the back door.
Lanfax Labs: Detailed information about laundry liquids and powders to help you select one that will not harm you garden.