Solution? Mulch pit. The basic premise is to feed all the water into a big hole that you have plants growing around. The plants take the nutrients from the water, thereby filtering it, and don't need additional watering. You can also throw anything organic in there to dispose of-we're sticking to plant waste at the moment, it's a great place for the endless gum leaves.
We'd worked out the placement before we moved in, so I got the husband to dig us a great big hole. He likes digging, the crazy man, and managed this in a pretty short time, even though he had to revert to banging away with the crowbar for most of it. He used all the dirt he dug out to build up the walls around it. We stuck the bananas we already had in straight away as they were looking rather sickly in their buckets of water, and stuck the greywater hose in and emptied the washing machine to check the level.
Once it was all sitting fairly evenly it was time to put all our wrecked moving boxes to good use-it's simply too dry here for sheet mulching. I also chucked some compost in, to give it a nice headstart on the organic base. There's no worries about the water percolating too quickly here, but I thought the compost and boxes in the bottom would slow it further.
Next, we filled it with anything organic we could find. I was throwing whole saplings and such in there. It was a convenient place for all the weeds around the area, which was previously cleared but then abandoned. So the pit received lots of stinking roger, wild cotton and of course the infernal periwinkles and lots of lantana.
We're slowly planting paw-paws between the bananas, and will fill the rest of the edge as soon as we can. There's also comfrey on the bottom wall-now i've finally cracked germinating it (only took me a whole packet *blush*) i'll be able to cover the wall much quicker.
So far it all seems to be working really well-there's rarely any smell and when there is it's very faint, and only discernable when you're right next to it. And it gets everything, even the nappy wash water-I know it's a no-no, but where else am I supposed to put it? I figure we're not touching it and it's well buried under all the mulch. 'Everything' is of course all greywater safe, low sodium and low phosphate, i'm not pouring Draino down there.The main issue is keeping it topped up with mulch, it eats mulch at an astounding rate. To give you an example of just how well it's working, here it is after three weeks of no water (us away), in stinking hot, dry, windy weather.
The bananas looked utterly fantastic, and the weeds are loving it (easy mulch!). It's now fenced, as the wildlife found paw-paws and comfrey quite tasty.
Further plans include
-Filling the whole edge with alternating banana/paw-paws.
-Using the comfrey wall to slash for mulch/teas/compost, much needed with our awful soils.
-Some reed beds on the upper side, for more mulch.