Grey Water System

The weekend grey water workshop was a big success thanks to everyone who came to help. Many hands certainly do make light work! Special mention to my wonderful Dad who managed to escape the group pic.

This weekend we were working on my grey water system. The idea was to set up a filtration system, so that the water that comes out of my house (from the kitchen sink, bathroom sink and the shower) is cleaned and ready to be reused on the garden. This reduces waste and also means my tiny house can safely process my waste water without being connected to services like septic.

What is grey water?

Grey water is waste water from the house that does not contain any faecal matter (no toilet water!). Any water that contains faecal matter is called black water and is not safe to reuse in the same way as grey water. Grey water systems commonly use water from the laundry, and sometimes also treat water from kitchen and bathroom sinks.

I watched a few videos on grey water systems and it seems that there are lots of ways you can set up self-contained filters to clean the water for reuse. I found this image a while ago (credit to Ecoedge), right about the time that I bought four old potato crates. It seemed like a perfect use for the crates and less messing around than trying to make an in-ground system.

How the layers work

The box has five layers to create the filter. The first layer to go in will be the last layer in the system, as water falls from the top to the bottom.

1. Plastic

   First thing to go in the box was plastic, to waterproof the system. We pinned the plastic to the box with some left over house wrap tacks. Dad donated a stash of old plastic that he’d salvaged ages ago for creating a water feature that worked a treat.

   

2. Carpet

   I saw this on a video for creating wicking beds actually. The carpet is to stop any rocks poking holes the plastic. The water will pass through the carpet, but this also forms part of the outer ‘waterproof’ layer around the outside of the system.

3. Rock

   Scoria went in next, to create drainage for the water as it falls to the bottom of the box. Getting the rock up to the system was an adventure in itself, the mower struggled a bit with the hills (and reversing, as pictured here), but we got there in the end.

4. Sand

   Sand will act as a fine filter in the box, collecting any little particles that might still be in the water as it reaches this layer. I bought the sand from a local garden supplies shop. I’m not sure what kind of sand works best in this kind of system – whether it’s best to use something coarse or fine. I went with triple washed (sandpit) sand because that’s what the guy at the shop recommended and it was the finest sand, better for catching left overs I figure. Also, the kids are keen to use the leftovers for their own project – sand pit time?

5. Soil

   The soil has water plants growing that will suck up the nutrients from the water as it comes into the box. At some stage I’ll try and introduce some compost worms in this layer as well to break down any chunky bits that come out with the water. The challenge there might be having enough food for the worms! For now, hopefully the plants will do enough of a job.

Drainage

The other key element of the system is having somewhere for the water to drain out once it has passed through all layers of the system. We cut a hole in the bottom of the box and used some left over plumbing pipe to create an outlet where I can catch the clean water. The pipe passes through the plastic and the carpet, with a clear opening in the box for the water to run out of when it reaches the bottom of the system. Some old aggie pipe over end of the outlet protects it from any rocks getting in and blocking it up. Then I taped the plastic around the pipe (with house wrap tape) to keep it as waterproof as possible.

I will also add a hose on the pipe where it comes into the box. This will allow me to move the end of the hose around the box and make sure there is an even spread of water and grey water waste material.

The system is bit of an experiment I’m not sure how important the technical details are – such as how deep each layer needs to be. We made educated guesses and went for roughly 300mm of each layer, plus a little extra rock on the bottom. I figure I’ll find out sooner rather than later if it doesn’t work!

Again, I owe everyone a massive thank you for the extra help, it was a relaxed, fun and very productive day. All in all, I’d say the tiny’s first working bee was a giant success!