I was wondering if you thought it might be possible to make greywater potable? My wife and I are going to be getting an RV here pretty soon, and we want it off-grid. We're removing the toilet and putting in a compost toilet, so we won't have any water wasted in flushing. We're also planning on putting in a filtration system to make rainwater potable (the assumption being that where ever we park the RV, we probably won't be able to dig a well.) I like the idea of taking our dishwater and shower water and purifying it to make it potable, so as to institute almost a kind of closed-loop system. We hope we can have a garden patch, but I don't think we're going to go in assuming that right now, and I really don't want that water to go to waste, if we can help it.
The tl;dr of this is: would I be able to put a filtration system on our greywater tank that would allow us to cycle it back into our drinking water system?
You'd do really well to get Art Ludwig's book, Create an Oasis with Greywater.
His website also has a huge amount of information.
I learned a huge amount from this book and I'll be pulling it off the shelf and rereading sections for years. If you're considering any type of greywater system, Art Ludwig seems to have seen that type of system be installed, and how it works or fails.
I have two ideas related to your question (based on the book, which i can't recommend highly enough):
1) Any kind of greywater system that involves pumps and/or filters is likely to keep requiring maintenance. If you are not mechanical or you don't like pulling hair out of a stinky gooey pump on a regular basis, you may want to avoid those systems. Ludwig points out that the organisms in topsoil or mulch are great at purifying greywater, while providing water to plants.
2) Before installing your greywater system, ask yourself what your needs and motivations are. If you really will be in places that have no other source of potable water (middle of the Sahara, perhaps? The Space Station?) then the expense of installation and maintenance would be worth it. But if you are in the US you can probably get other potable water much more easily. The filtration unit you're imagining might turn out to be more bulk to carry in your RV than to occasionally carry water tanks in the RV when you happen to be going to places with no potable water nearby.
There are lots of small and simple camping water filters that will make slightly dodgy but clear-looking water safe, if you camp near a stream, for example.
Works at a residential alternative high school in the Himalayas SECMOL.org . "Back home" is Cape Cod, E Coast USA.
Seems to me you could do this with a three step process:
Constructed wetlands to remove the bulk solids and most of the BOD, slow sand filter to remove the rest of the BOD as well as most pathogens, and then a ceramic micro-filter system.
While relatively economical, and mostly renewable, this system would be quite large, probably too large for an RV.
Mechanical filtering to remove solids, followed by Reverse Osmosis, or distillation might be workable. However, both distillation RO generally produce waste streams of water that are often larger than the processed streams. These could be fed back into the greywater, but eventually undesired contaminants will build up and you have to flush the system and start over.
My opinions are barely worth the paper they are written on here, but hopefully they can spark some new ideas, or at least a different train of thought
Michael cox posted this in one of my threads. I think it applies here. Its a start to finish wood fired distiller using sticks and mud(clay). Once you understand the concept, it can be built many ways, or buy an off the shelf unit.
I suggest you look at the practicality of it.
Cost of components is one aspect, and room on the RV for another.
You may be better to fit a tank you can fill or top up when ever you get fuel.
As for rainfall collection look at having an awning on the side with a gutter. Then look at 'Benefits of rainfall collection" here somewhere under homesteading I think.
John Daley Bendigo, Australia
The Enemy of progress is the hope of a perfect plan