Here's how I do it:
1. Collect the shower warm up water
2. Dump the shower warm up water in a bucket
* At this point you can do one of two things:
- leave it at that and only use this water - doing this means that you can put the water directly in your toilet tank as follows: next time you flush the toilet, empty this water in the tank as it is filling. I don't do this because it sounds like it takes a lot of coordination, plus I only collect 1.5 litres of warm-up water per shower. Or
- you can keep going and collect the grey water too:
3. Put the plug in the shower to stop the water draining out
4. Shower. Navy style.
5. Collect the soapy shower water. Yes. That's my shower water. What, you thought I'd waster a shower's worth of water for this demo? :-) Don't be grossed out - its only soapy water.
6. Dump this water in the bucket along with the other water
Now you have your water collected, here's how you use it...unlike the shower warm up water, it is not recommended that you put grey water in your toilet tank. The soapy residue can gum up the working parts. Also if you have a fancy toilet, you know, like a dual flush one, you might have a warranty which would probably get voided if you put soapy water in the tank. So what do you do?
It's the easiest thing ever.
You won't believe it.
If you pour the greywater, from the bucket, directly into the toilet bowl, the toilet will.....flush. For reals folks. Takes more water than the toilet would normally use to flush (at least half the bucket) however the net effect is zero as this water would have gone down the drain anyway in the shower.
So there you have it - the totally low tech, no cost way to recycle some of your greywater.
If you are more of a fan of high tech, this system, sounds interesting (bonus - its a Canadian company - based in Montreal). It uses chlorine though.
And here's another low tech option for capturing greywater.
You can also use greywater to irrigate your garden. Check out the water purification/irrigation system in Earthships.
Oh and one last thing. If you are going to capture your greywater and don't plan on treating it (like with the bucket method), you should use the water within a day. After that, the water can grow bacteria and will generally be unhealthy to have around. If you haven't used it within a day, it's probably best to dump it out.