Ask the flist: Greywater DIY?

[andygates]

Has anyone got any wisdom to offer with regard to installing a small domestic greywater system?

With the walls off my bathroom, I can see almost all the pipework.  There's plenty of space back there.  I'd quite like to intercept the sink waste and use it for toilet flushing.  The pump and overflows I can probably manage.  How about treatment? 

Comments

[ravenbait.livejournal.com]

Um.

If you want me to design something for you I'll need a lot more information.

[andygates.livejournal.com]

Here's some:

Washing machine does on average 2 loads a week. One washing-up bowl of water with icky bits per day, a couple of bathroom sinks. Shower every other day. Something like six toilet flushes a day. That's the water volumes involved.

The kitchen wastes join the bathroom waste on the way out. There's very little head on the pipes, it's all on a (gently sloping) level which, alas, is about .5m below the toilet cistern intake.

So, is it even worth the faff?

[ravenbait.livejournal.com]

Depends on what you think is faff.

Do you have a hippo in your cistern?

Washing up bowl shouldn't count as greywater because of the icky bits. What do you want to do with the water? I need to calculate salt concentrations and I'm concerned by the icky bits. Could you separate the solids?

[andygates.livejournal.com]

I have a brick in my cistern.

Faff? Installation faff is not a problem; servicing stinky filters every week would be. I'm only thinking of using it to flush the loo.

Removing the ick from the kitchen water would be prone to occasional errors, so to speak.

[ravenbait.livejournal.com]

It makes a difference in terms of solids filtering, that's all. It should be possible, although, counter-intuitively, it's easier with larger volumes because the dilution is greater. Let me do some sums and get back to you. You might need to put a small reed bed next to your wormery if it's too concentrated.

[ravenbait.livejournal.com]

Just for the record, you'd need to deal with a certain amount of contaminants to put it back in the cistern because some bacterial components will multiply to the point of significance just while you're at work. Most systems use a biological filter and that's very salt sensitive.

Are you in a rush or can you give me time to calculate? I might have a few more questions for you if the latter.

[andygates.livejournal.com]

No rush. But to be clear, I'm only thinking of using the waste water for flushing so it would go into the sewage. The garden's well provided for from my rain water butt ;)

Heh, I said "butt".

[gedhrel.livejournal.com]

Could you do the calculations in public? I'm curious to know what you're working out. We're looking to sort out the bathroom this year - as Andy says, it's a source of lots of grey water. Cheers,