Dark greywater questions

Hi Art-
Welcome to the forums! So glad you could make it!

It is my understanding that you have said that water from laundry washing machines can be used as a source for greywater. (Don't you have a DVD out about Laundry to Lawn or something like that?) I further understand that water from tubs and showers can be put into a greywater system. Now both of these are potential sources for removal of feces (e.g. small amounts stuck to human bottom, dirty cloth diapers in which not too long ago I was up to my armpits, etc.). I used to wash soiled cloth diapers in the washing machine. So, I have a few questions for you regarding so called dark greywater, i.e. greywater that has potential to be considered as blackwater.

--At what point does greywater become considered dark greywater? Similarly, at what point does dark greywater become blackwater? I'm curious both from a legal standpoint and from a more practical standpoint. For example, if I were to wash in the tub just after having defecated (but having wiped thoroughly), I would assume that is considered still greywater. Correct? However, if I am going to be washing lots of cloth diapers do I need to consider it blackwater? Are there certain things (e.g. coliform, etc.) that we need to test the water? If so, what concentrations are considered the range for each category? Or perhaps, is it more of a non-precise continuum; you'll know it when you smell it?

--Does contamination of a greywater source last indefinitely if the source of blackwater is removed? For example, in the case of cleaning the dirty cloth diapers in my washing machine, do they permanently contaminate my washing machine or can I safely say that after x number of washing other non-blackwater rated material it would be safe to say it is a greywater source? Would I need to disinfect the washing machine?

Thanks for all your help in understanding these questions (and all the other ones on the forum too)! I am pretty sure that I can safely say that we are all overjoyed to have you out here sharing your knowledge on this matter!

Matt,

(thought I already posted on this one, too...hmm.)
(Don't you have a DVD out about Laundry to Lawn or something like that?)
Laundry to Landscape
Laundry to lawn= common error x2 (one having a lawn, two irrigating it with greywater)

--At what point does greywater become considered dark greywater? Similarly, at what point does dark greywater become blackwater? I'm curious both from a legal standpoint and from a more practical standpoint. For example, if I were to wash in the tub just after having defecated (but having wiped thoroughly), I would assume that is considered still greywater. Correct?
Yes.
...if I am going to be washing lots of cloth diapers do I need to consider it blackwater?
Legally, yes. Practically, your home and everyone in it is already covered in a light sheen of baby fecal matter, so the significance of the added exposure from having the laundry water under mulch out in the orchard = nil.

Are there certain things (e.g. coliform, etc.) that we need to test the water? If so, what concentrations are considered the range for each category? Or perhaps, is it more of a non-precise continuum; you'll know it when you smell it?

I don't think anyone has really pinned this down quantitatively, either legally or practically. Having done thousands of fecal/ coliform bacteria tests, I think testing greywater for most people would be a waste of time and money, because there is a tremendous amount of noise, it raises almost as many questions as it answers and it takes a lot of data for an accurate mental model to emerge from the fog. (If you want to do this for drinking water, wild natural waters or blackwater though, see Water Quality Testing: How to Do Water Tests Simply, Inexpensively and Accurately

Speaking of accurate mental models, anyone interested in this topic must read this page we wrote on conversion factors between MPN/ 100ml and buttwipes per swimming hole, bathtub, etc.

--Does contamination of a greywater source last indefinitely if the source of blackwater is removed? For example, in the case of cleaning the dirty cloth diapers in my washing machine, do they permanently contaminate my washing machine or can I safely say that after x number of washing other non-blackwater rated material it would be safe to say it is a greywater source? Would I need to disinfect the washing machine?

The concentration of pathogens will dilute logarithmically with each clean washing. After say, two clean washes I reckon you'd be back to background noise of the fecal coliforms that are blowing through everywhere from dried dog feces and whatnot.
Only if you plan to convert the washer to a drinking water or beer making vessel would it make sense to disinfect it.

Thanks for all your help in understanding these questions (and all the other ones on the forum too)! I am pretty sure that I can safely say that we are all overjoyed to have you out here sharing your knowledge on this matter!

You're welcome--it's been a pleasure, and with that I'm signing off —

Art

Hey Art-

Thanks for all the information. I look forward to taking a look at the links. I'm pleased to know that my washer is not going to be harboring any germs after just a few washes.

Thanks again,
--matt

P.S. For those interested in more talk on greywater systems with respect to cloth diapers, please see this thread on permies: https://permies.com/t/32956/grey-water/Cloth-diapering-water