Greywater toilet flush systems

[Andy Dingley]

I'm considering converting an outside toilet into a downstairs toilet, making it accessible from inside the house.

More drastically, I'm also considering a greywater flush system for it. this would be fed by the shower / bathroom on the floor above. For simplicity, the upstairs toilet would remain with a potable water flush.

I'm interested in systems such as the Ecoplay

that take an "active" approach to managing their input greywater. This also uses two tanks to process it, one as a reception and separation process ("too light" and "too heavy" fractions are both discarded) and another for storage. If the bathful isn't used quickly, it's also discarded. There's reversion to a potable supply, if all other sources fail.

Naturally for this ng., I want to build my own...

Any advice to offer?

Thanks

[meow2222]

only some discussion of a much simler system

[Rod]

Interesting. Given different circumstances, I too might have been interested enough to consider trying something.

I read the link - and was surprised about the Spanish hairdressing chain. I couldn't help wondering what would happen to hair dye being pushed through this system. Would it get floated or sunk out (can't see why it should)? Or would you be flushing coloured water with the potential to dye loos and, given splashback, bums (you're worth it)?

Does this sort of system require care with choice of bath/shower cleaning products? I can imagine paste cleaners causing clag ups. And as for caustic soda, sulphamic acid and the other nasties sometimes mentioned here.... :-)

But I think my main question is how much does this (the commercial vesion - not your diy one) actually save in an ordinary family home? In cost terms, I'd bet you can get an awful lot of water for the cost of the system itself - especially if you include installation. The amount of water saved then has to be balanced against the materials, electricity, etc. that it takes to fit and run.

[andrew]

This sounds similar to the Bywater process that wa developed for water purification in developing nations.

AJH

[Andy Dingley]

system

so much "simpler", more "completely different source".

The first big question with all of this is what to use as the source - rainwater or greywater. The Ecoplay system targets greywater because it's intended for high-density use (and possibly low-density use) where there just isn't the rainwater available. AIUI, rainwater systems need more storage volumee, for longer, and this makes them more troublesome than the shower greywater systems.

[Mary Fisher]

We looked into this. It was horrifically expensive :-(

So we bought a dual flush which uses minimal water. All rain water from house, sheds, garages and greenhouse roofs are collected in butts to water the vegetables. Bath and shower water is wasted, sadly.

It will be interesting to know what and how you do it.

Have you considered a compost toilet instead of a water flush for your second toilet? We have but it won't happen yet.

Mary

[Andy Dingley]

Was that an Ecoplay? And how much is "horrifying" ?

Not beyond the "That's impractical" stage. Nice idea, but it's rarely practical except on new build.

It's also likely that the current outside toilet will become the main toilet in terms of volume. Although the Ecoplay can use a pump to supply a toilet above the main storage, I'm thinking that wouldn't actually be justifiable (pump plus extra pipe run). The nice thing about fitting greywater to the outside one is that most of the plumbing is already coincidentally in place.

[meow2222]

If the eco system turns out to be too expensive, there is an ubersimple option, the japanese approach. The hand basin drains directly into the bog cistern, so when you wash after use the grey water gets reused. Keep the mains fill but adjust it to a slow fill and you'd use mostly grey, but mains fill always happens regardless of sink use.

The main point of such a setup is trivial install cost, making payback possible.

NT

[Andy Dingley]

The numbers just don't work out with that system. Our bigger problem isn't to force "all water to be used twice", it's to reduce the amount of primary potable water going into flushing. The handwash volume just isn't enough to make a useful dent in the flush demand.

So long as we don't run short and have to revert to using the potable supply for flushing, we don't care too much about "conservation" of the grey. That's the key point behind realising that a "short-term storage only" approach (with simplifications for treatment needed and possible yukk factor) might be "wasteful" if it throws this carefully hoarded water away every couple of days, but it's actually the more efficient system when considered overall.

This doesn't mean that routing the basin waste to the cistern isn't a good idea, just that it's not as good as trapping the bath or shower waste.

[Mary Fisher]

I don't think it was. It was over £600. I could find the info.

It can be ...

I didn't realise that it was an outside installation. That could complicate - or ease - things.

I'm confident that you'll find the optimum solution for your situation!

Mary

>

[Mary Fisher]

Payback is NOT the only consideration!

[Mike Tomlinson]

In article , Andy Dingley writes

As an experiment last year, I collected grey water from a bath drainpipe and stored it in two linked water butts to use for watering the garden. It worked okay - a surprising amount of water was collected, even though only the shower is used - but the grey water began to stink after a short time. You would either have to use the water very regularly, or treat it in some way.

I gave up on the experiment when I moved house, but took the butts with me to use for another project.

It'd be interesting to hear how you get on.

[John Stumbles]

Maybe you could combine it with the turf roof idea and have a phragmites reed bed on the roof of the WC cleaning up the water as it goes into the cistern? ;-)

[meow2222]

yes obviously. Its just a no cost small gain.

NT

[David Hansen]

On Fri, 30 May 2008 07:27:45 +0100 someone who may be Mike Tomlinson wrote this:-

One approach is to use the grey water directly to water vegetable beds. Provided the grey water is introduced into the beds via irrigation pipes under the top of the soil there is no smell and no problem eating the vegetables.

Rainwater is probably the best way of flushing toilets in an existing building with limited space around it. It can also be used for the washing machine and watering the vegetables if they need it. Combined these will dramatically reduce the use of mains water and reduce the amount of water sent to the sewerage system.

With a new building or some land around the water can be managed in more advanced ways. One example is to use rainwater exclusively. Collect it from the roof and filter it to provide water for sinks, bathing and do on. Send it through a UV filter as well for drinking water. When it has been through the basin/shower filter it in a plant bed (some of the plants being edible). Then use this water to flush the toilet and water the plants if necessary. Then take this water to a greenhouse and use it to water the plants. All the water will be taken up by the plants, there will be no water emerging from the greenhouse. One can see such a system in operation by visiting and the guide they publish explains it in some detail.