Look into micron filters or even submicron hollowtube filters. They’re washable and reusable, they filter out most suspended solids, some heavy metals, and even pathogens (most bacteria and parasites, even some viruses).
I don’t think they’d make grey water potable necessarily, but if you’re worried about bathwater contaminating your garden then combining these with switching to biodegradable soaps and solvents is probably enough.
Adding a charcoal filter stage might bind some stuff that the hollowtube misses. You can even run it through a UV chamber if you want another line of defense, but that’s a bit slower and might be redundant, especially if you’re just watering your garden.
There are also ceramic filters out there that are supposed to remove pretty much anything the hollowtube filters would miss, but they’re more expensive and the parts aren’t quite as reusable. Supposed to make pretty much anything potable though.
I’d have to do more research about dissolved particles, but I think some of the filters mentioned can catch some of it. Otherwise it would require distillation or reverse osmosis, both of which are slower and require more expensive equipment. Building a solar still is an option but it’s the slowest one.
MouldyCat@feddit.uk 2 days ago
I also looked at this recently as I thought that soap would be harmful to plants and/or microbes and the Royal Horticultural Society has done some investigation of their own into the use of greywater, and their advice is “plants can be watered with shower, bath, kitchen and washing machine water (from rinse cycles)”, finding that “soil and potting composts are effective at filtering out” the soap/detergent.
I’m just echoing what @Denjin@feddit.uk with the RHS link, and I didn’t read the articles he linked but it wouldn’t surprise me if the RHS guidance is the source of those.
HerbGrower@slrpnk.net 2 days ago
I wonder if I would need a pump or could connect a tube directly to the bathroom tap/shower outlet at the side of my house. It is only elevated slightly above the ground, it looks like the path is flat but there could be a slight gradient either way that I am unaware of. Kitchen outlet for the washing machine and kitchen sink is a bit higher. But I think the bathroom water is a cleaner source.
Either way its something to look into trying. Pipe probably doesn’t cost much to experiment with and can be removed when not needed. Worst thing that would happen is the shower fills up and you notice that pretty quickly, then just take it off.
MouldyCat@feddit.uk 2 days ago
pumps are cheap enough but they probably increase the chance of blockage due to hair and so on. if you could get it using just gravity it would prob be better from a minimum maintenance viewpoint.
HerbGrower@slrpnk.net 2 days ago
Yeah gravity would be less maintenance, just a tube at that point.
You can get pumps designed to go under the shower by the look of it but then you need to power it. Otherwise DIY options, might be some battery powered pumps that could work. Thought sump pumps perhaps but apparently those are rated for many many thousands of litres an hour. Maybe if I can find something smaller than that…