Great Idea! I think the only problem is: where do we store that gray water? You need an extra container or so to store it temporaly, this means extra costs etc etc.

I've heard that Japan already has this figured out - the tank for the toilet holds the water. Instead of having a sink on the other side of the bathroom, they have a sink right above the toilet. The water that you use to wash your hands goes into filling the tank of the toilet, which is used for the next flush. Doesn't save a whole lot of water, but I suppose it adds up. Also, I'm not sure that people would want all that gray water hanging around in their toilet tank. I would think it'd get pretty nasty in there after soapy water has been sitting in it for a while.

But I like the idea - seems elegant.

Here's a follow-on idea. If people don't want gray water hanging around - why not use the hot water that's going down the plumbing to heat the floor? Use the heat from the shower to warm up the tile right outside the shower - who wouldn't want that?

The way you'd do it is have a cistern in the basement, which is pumped as needed to toilets (overflow going to the sewer),or a cistern in the attic (pumped from a collector in the basement), gravity feeding the toilets.

There are ways to naturally pre-clean the water so that recyvling it on the discussed manner isn't so bad.

You would still have to filter the gray water somehow. In Houston, a lot of the storm drains do not go to the municipal water system but are instead dumped directly in natural bodies of water.

This means dumping, say, motor oil on your driveway will put it right into Houston bays. If you were to dump the motor oil into the shower, it would go to the highly regulated filters of the municipal water system. If, say, shampoo were to runoff from everyone's gray watered lawns, would it hurt the watershed? Who knows. Is it still worth it? Maybe.

Would only work in dense urban areas, but why not have two water systems ? Toilet water goes to ABC processing plant, all other gray water goes to XYZ processing plant which doesn't need nearly the amount of refinement/cleaning then can be resent to toilet water intake

The simplest and cleanest source of graywater is the output from your washing machine, as long as you are not washing diapers or items used by people with infectious diseases. Store it in a tank and use it to flush the toilets. If you have more than you need for toilet flushes, and if you're using eco-safe detergents, you can use the surplus to water the yard, water indoor non-edible plants, or wash the car.

Water from the shower needs to be filtered to remove hair etc., and also bleached to sanitize it. Water from the washer has already gone through a lint filter, and the occasional load of laundry that uses bleach will keep the storage tank reasonably clean. (You can also add a tablespoon of bleach to every 15 gallons of graywater to keep it clean. However, graywater cannot be made drinkable without more extensive treatment.)

I'm in the process of building a semi-automatic integrated graywater system that will be user-installable and also viable for apartment dwellers; when it's ready I'll publish pictures and plans in a suitable forum.

Note: using any kind of graywater on edible plants is a potentially serious health hazard; if you plan to try it, do your research carefully, and test your graywater supply to be sure it's clean enough for the intended purpose.

I've thought about doing this, at least using greywater from the washing machine and the dishwasher to use in the toilets; plumbing a greywater drain wouldn't be a problem, I have access to a clean plastic 55 gallon drum that was used to contain detergent, so a storage tank isn't the problem- the problem is space, I have little room to spare inside my home.

i think this is a clever idea. it reminds me of the movie "waterworld" where kevin costner urinated into some sort of contraption and when it came out, it was drinkable water! i think this is highly possible, if extensive research is dedicated to it. water technology has greatly advanced in the past ten years with ozone treatment and even water as a source of energy for cars. You never know...this may be found in every household in the next 10 years.

Oh man... Does that mean when I let it loose into the toilet I risk having gray water splashing up into my...?

Diverting gray water to reuse seems to make sense until one takes into account that municiple sewage systems rely on a large flow of water to operate efficeintly.

Most cities have already separated the storm water system from the sanitary sewer system. The decreased flow requires that crews periodically "flush" the sanitary sewage pipes to ensure back-ups don't occur.

Using bath water to flush the toilet might work out OK but using it to water the lawn would only result in more water being used by the city crews

In San Jose, we reuse stormwater and maybe residential drainwater. It undergoes filtration similar to source water and is used mainly for business irrigation. Despite the methods used, officials warn against using it like potable water.

I suppose if enough new plumbing was provided, this could work. I don't see this happening in existing structures. In addition, tank water from your toilet (not bowl water) is recommended as a source of emergency water should the main be unusable.

Storm drains currently seem to be inefficient, otherwise why is there flooding? Can't engineers design better drainage systems so flooding will be eliminated?

Storm drainage systems are designed to handle the average high rainfall. To build them to handle the exceptionally large rainfall would make them much more costly. And municipalities are all in some sort of budget crunch these days.

So they don't design a system that will last 50 years to handle a downpour that statistically occurs every hundred years.

We could go a lot further once you filter and pump it but why...There is a simpler solution...catch the run off rain water from your roof to an intermediate storage tank to fill the toilets, the washing machine,water the lawn...etc. via gravity. No pumps needed, no fancy filters.

No it is not potable without filtering of course but very easy to do anda small rain can easily fill two or more 55 gallon storage tanks from theaverage homes run off via the gutters.

Catching the rain seems like a good idea until you have the summer we just got through. I didn't rain appreciably till the middle of October, with wells drying up all around. I am currently looking for a way to reuse bath/shower/sink waer to do laundry. I think the rain would work as an alternate but would still require filtering.

The problem with this is that when people put stuff into the drain they assume it's going away forever....so dirt, soap and other debis is going down the drain and, in your scenario, into your toilet or some other system for reuse. So the equipment that would "reuse" the water would have to be equiped to handle dirty-water.....currently most stuff in your household is not, most can barely handle "clean" water.