Last week I posted a description of our laundry-to-landscape greywater system. I talked about how I hooked up the washing machine to receive fresh water and drain the waste water. Today I want to talk about what I put *into* the machine. When you start using a greywater system you have to make a mental shift and start considering everything you put into it. Namely because everything you put into it is going to come out of it, in this case right onto your landscape (soil, trees, garden, whatever). There are three different products that people typically use in their washing machines: detergent, bleach (or bleach alternative), and fabric softener.
I will say right now that I think fabric softener is a horrible product that coats all of your washables with a terribly water-repellant coating that smells of chemical perfumes. Yes, your towels are luxuriously soft but they do not absorb water so you basically just smear the water around on your body and are left damp-skinned and laden with chemical residue. (Goodness, I hadn't realized just how strongly I felt about that.) So scratch the fabric softener. Let's move on to bleach and bleach alternatives.
Bleach and Bleach Alternatives
I have never used bleach on a regular basis but I do recognize that there are things that need an occasional bleaching for sanitary purposes. (Like my moldy shower curtain and all those old rags I used in the chick brooders that got chick poo all over them.) Because I don't want to send bleach water out into my yard I use a 5-gallon bucket to soak items that need sanitizing. Then I dump the dirty bleach water on my driveway where it evaporates before reaching any soils. Another alternative would be to dump the bleach water down the toilet where it would be sent to the septic system or sewer. (You don't want to send too much bleach water into an aerobic septic system but a small amount is okay.)
So we can't put fabric softener and bleach into greywater systems. What about laundry detergent? I have done a lot of reading about appropriate detergents for greywater systems and most sources point to just one product that is completely safe: Oasis Biocompatible Laundry Detergent.
Regular laundry detergents, even the biodegradable or "free" kinds, contain sodium. Sodium salts your soil, which is bad for plants. Many detergents also contain boron and/or chlorine and those are also bad for plants. The Oasis Biocompatible detergent is the only laundry detergent I've seen or heard about that doesn't contain sodium. The manufacturer claims that it breaks down into plant nutrients, namely potassium and sulfur.
The best source for Oasis detergent that I have found is iHerb. One gallon of detergent is currently $25.10 and if your order totals $40 or more you get free shipping and pay no sales tax. So I order two gallons for a total price of $50.20. I use 2 ounces per load of laundry (if you have a high-efficiency machine you can use just 1 ounce). That is 64 loads of laundry per gallon for a cost of 39 cents per load. (That is only 20 cents per load for those of you with HE washing machines!)
I should mention that I only recently started using the Oasis detergent, which means that I was using regular laundry detergent in my greywater system for about a year and a half. I did make sure to use detergents that were free of perfumes or dyes or bleach alternatives. Because I move my drain hose frequently and have a large area available to receive the drain water I was less concerned about salting the soil. Also, I was not watering any valuable plants or a vegetable garden. I did worry that I couldn't continue to use sodium-based detergents forever, though, so I made the switch to the sodium-free detergent.
In case you are wondering why I didn't just start using borax or washing soda instead of laundry detergent, it's because those chemicals harm the soil, too. Borax is sodium tetraborate decahydrate and washing soda is sodium carbonate (sodium again!). They are great options for a regular laundry system but not for greywater systems.
So here are my brief guidelines for safe greywater washing:
1) Use Oasis Biocompatible Laundry Detergent
2) If you have to bleach something, use a bucket
3) Don't use fabric softener
That's it! Happy washing!