I used a toilet once that was connected directly to the sink next to it. The sink had a faucet but no controls. When you flushed the toilet the water started coming out of the faucet in the sink so you could wash your hands, and then was routed from the sink's drain directly to refill the toilet's tank for the next flush. When the tank was full the sink shut off automatically.

It was genius! So simple and cheap yet effective. An interesting side effect is that after you flush the toilet the sink's faucet runs for quite a long time, which really makes you appreciate how much water is going in to each flush. Why don't all toilets work that way?

This sounds amazing. Was it just a proof of concept or an actual marketed product installed somewhere? Commercial or residential setting?

Something along this approach has been used in "modern" house hydraulics in the last few years here in Italy, though not common, as it is used only AFAIK in self standing houses (not apartments buildings).

In practice there is a reservoir where the "almost clean" waste water (i.e. what comes out of the bath sink, bidet and shower/bath tub) is accumulated.

Toilets are fed by a pump with water coming from this reservoir, in practice you use the same water two times.

It’s an actual product. My grandma in Australia has had one for 10 years.

I’m guessing it never took off because we don’t have that much of a water shortage in most places that washing hands is a luxury.

It was at a place called Cypress Valley outside of Austin, TX. https://www.cypressvalley.com

Note this was many years ago...

Pretty common in Japan, if I recall correctly.

Yep, used these myself multiple times.

They have used human feces in North Korea to fertilize their fields with the effect that people got worm parasites:

> https://www.cnbc.com/2017/11/16/body-of-north-korean-defecto...

Also, human feces can contain anti-biotics and other stuff that you shouldn’t be spreading over soil. There is a reason why hospital waste water gets special treatment before disposed of into the sewers.

I don’t think using human feces as fertilizers is a good idea.

It is, at least where I am coming from, well-known that raw human feces must not be used for fertilizing soil; However, composted (long enough / on high temperature) would break down the pathogens that are bad for humans.

See more on wikipedia about fertilization using human feces [1] and in general, applications of composting toilets [2].

[1]: https://en.wikipedia.org/wiki/Human_feces#Use_as_fertilizer

[2]: https://en.wikipedia.org/wiki/Composting_toilet#Applications

When my father was stationed (in the US Army) in South Korea in the early 1960s, human "nightsoil" was the primary fertilizer there as well. It's an obvious source of cheap fertilizer, even if it has some health drawbacks. Obviously the economic success of the South has allowed it to not do that anymore.

> Flushing toilets with potable water seems just very wrong, and a luxury I always thought western societies can afford only.

I assume the cost and potentially even environmental impact of reusing existing potable water infrastructure to provide water for toilet-flushing is much less than manufacturing, installing & maintaining separate local systems (to collect rainwater, etc) for this purpose.

Depends how much water costs; in the UK water is cheap compared to the cost of a plumber, but the UK is famously moist. I wouldn’t be surprised if plenty of more arid environments would find the cost going the other way, and preferring some combination of rainwater collection, greywater reuse, or non-water-based toilets.

You are absolutely right, however, as ben_w below also pointed out, while the economical / environmental impact might not be justifiable in our western bubble, it might be outside of it.

There are still places on this planet where clean drinking water is a scarcity, and therefore - along multiple other reasons - water-flush toilets and accompanying infrastructure cannot be (easily / justifiably) built.

However, as we can see there are different solutions to the problem itself (health-risk free, humanic way of taking a dump) without using up gallons of water.

My house has a non-potable water supply used for irrigation, and is in fact required by the town to. I know the same is true in some parts of Utah and probably other places. In such cases, also requiring toilets to be supplied by the non-pot line would be a trivial cost that would pay for itself eventually.

If you’ve already got it then it makes sense to use it, but this doesn’t remove the cost of building and maintaining separate infrastructure at all.

In some cases it might be worth it or necessary, in others I think the process of processing & delivering potable water could be made (or is already) so efficient that building & maintaining separate infrastructure for non-potable water would be a net negative both in terms of cost and environmental impact.

There are plenty of places around the world with western style toilets but flushed with rainwater or recycled washing machine/shower water instead. That seems like a fairly sustainable solution that already works?

Yes, those are better solutions, however still not really sustainable, and without incentives to build the accompanied infrastructure, it's never going to be sustainable; whereas solutions like the composting toilets are fairly easy to implement - FWIW ~ that's what we had before water flush toilets, isn't it?

Speaking of eastern europe, here is some anecdata. There are villages and towns in Romania that received EU funding for water and waste treatment. Naturally money have been embezzled and instead what they got was “drinking” water with traces of fecal matter (bacteria and the resulting chemicals). When confronted about it, the locals (not even those responsible for the issue), said that the water tastes real good and are “proud” of what their mayors did to the water system. They even said its healthier than city water because it’s “eco” and has less chemicals. No less than 892 communes benefit from the blessing of “real good” water (a commune usually covers a few villages, so you can imagine the scale of the issue). And yes, they voted the same people back in and are staunch defenders of their “performance”.

Source (in Romanian, published by an investigative reporter): https://recorder.ro/harta-apei-contaminate-din-satele-romani...

Hi there; although I can relate the (corruption-induced) negligent use of EU-money in Eastern Europe, as the guidelines [1] instruct, please avoid unrelated controversies and generic tangents while commenting.

[1]: https://news.ycombinator.com/newsguidelines.html