It's not really grey water since it isn't used. It's the fresh water that you want to redirect to some kind of storage?

You don't need any special faucet. Just have the plumbing (hot only) branch off right before your shower faucet with a valve on it that you open to draw the hot water up to that point. Then you close the valve and start your shower.

This additional valve will direct the water where ever you want.

The only trick is how will you know when the hot water has arrived?

Personally, it seems like more effort than it's worth.

Maybe look into the hot water recirculation pumps where the water in the pipes is constantly hot. It's a bit of a waste of energy to save a bit of water. Depends on what's more important to you.

Or look at on-demand water heaters right next to the shower.

Yes it is fresh water, I just need something to control the flow. I am not planning to store the water. Will be using drip irrigation for the plants so it will not be in 1 place and it will get distributed.

Thank you for the comment, will check with my GC on the possibility.

I found this product from green smart but looks like the product is still not ready and it is being designed, I have sent an email to the company if they have it.

https://www.youtube.com/watch?time_continue=5&v=OYSdgJYlp8g

So you'd be directing the water directly onto plants? I hope you don't run the hot water too long before you switch to the shower. I can't imagine that plants would do well with hot scalding water poured on them. :)

The video you linked is grey water, because it's redirecting the drain to somewhere else. You're talking about redirecting the fresh water before it comes out of the shower and goes down the drain.

Eventually someday I want to use my shower water also but I am not sure if there are products in the market which are safe . So trying for a system which will be scalable to support drought if there is a need, as CA has had drought in the recent years and water bill is high.

The water will not be going on the plants instead will be going to the roots of fruit trees. Or we may collect it in a bin and connect it to drip irrigation system. We do not plan to store the water too long.

You are wanting to over complicate things that do not need over complicating. Put a 5 gallon bucket in the shower. You might get 3 gallons in it, and that's if you have to wait longer than 2 minutes. Which you won't. Then hand dip it out to water whatever.

It is easy to say to use a bucket, I have been doing it but it is harder to do it every day. My kitchen under sink water filter wastes 3 times the water what we consume for drinking and cooking. I get 1 to 1.5 buckets of 5 gallon for a family of 4. We drilled a hole from the wall and collect the water in the bucket in the yard. Then when I see it is full I try to hand distribute it. Doing the same for shower is not easy as you have to take the bucket on hardwood or carpet area. I need something to send the water out to the yard and I should be able to control the direction, if I am assuming chemicals then I will avoid the flow to yard - it can go to shower-> sewer or shower ->yard. With kitchen filter there was no confusion as there are no chemicals so it was easy to do. Now with shower system we are struggling to see how to build a control system so that we can choose when the water should go and when it should not go.

Then you are essentially already doing what I suggested for your shower with your kitchen sink. Redirect to storage outside.

Here's a quick sketch:

Tee off the hot water supply at the red mark. Put a valve at the blue circle. Run the pipe (black) outside to dump into a rain barrel or something.

You'll have to just learn by trial and error how long you need to open the blue valve before hot water is available so that you can shut it off and start your shower.

If you are looking for some automated item that detects when the hot water has arrived and automatically turns on the shower, then I have no idea if something like that would exist.

Could you use a tub diverter sort of like the one in the diagram? Would it have to be teed off the hot and not the mixed flow? Usually you'd only be running hot anyway at that point.

If you do vintage-style exposed plumbing in that area, you can just feel the pipes to know when it's hot.

Thank you Greg and Fiori for your inputs , will share your suggestion to my GC and hubby and see,

Green smart also responded back that they are selling that product, Will wait for pricing details from them.

If you can get a system going, please report back. I think there are systems for gray water reuse, and if everything else fails, perhaps you could do that and add the warm-up water to the gray.

Lugging a bucket full of water through the house isn't actually a good option!

Lose the reverse osmosis water system. It wastes way too much water. A standard treatment system will likely be more than sufficient and waste almost no water.

Green smart responded and the price tag for the valve and the controller used in the video is in the range of 200-300,since it is not sold by distributor so the price may change once the sales model changes. They will share the data specification sheet and we will have to see how we can map that to our project.

https://www.youtube.com/watch?time_continue=5&v=OYSdgJYlp8g

Once my hubby decides on which way to go, I will share the details.

The price tag for the Green smart valve and controller may only be 200-300 but then you probably have all kinds of code issues about storing and using the grey water. I'm not experienced with that, so I can't tell you what the regulations are, but it would be much different than diverting the fresh water. Presumably much more expensive.

But, if you set up a grey water reuse system, you'd be using all of your shower water and not just the initial runoff while you are waiting for the hot water to appear. So you'd have more 'free' water for irrigation.

Not exactly what you are asking for - but something to consider: Are you aware of the shower thermal shutoff valves that shut off the shower once it heats up.

Once it's warmed up, then you pull on a cable to turn the shower on again.

Another idea is to replace the plumbing with Pex. My upstairs shower with pex has hot water within a few seconds. Very little waste.

The downstairs shower with a shorter copper run takes considerably longer for hot.

In Europe there are so many more types of water conservation things maybe check out some of theirs to use. Get a new water purifier that does not waste water and really unless you get a really good way of saving the water this whole thing really makes no sense. Gray water storage to me is an awesome way to save water but needs to be installed by someone that knoes what the heck they are doing. The easiest way to solve your issue is on demand hot water next to the bathroom near the shower.If you really want to save the water there is a cool system that actually uses that water to flush your toilets.

Any reason you cant use a recirculation pump with your shower? They're easy to plumb (relatively) and the hot water side is recirculated back to the tank until it gets hot at the shower. No wasted water.

So far only washer dryer water is what is qualified as gray water by the city website. They may slowly add other system, washer gray water system is permitted without any permits. We want to build so that in future we can use it once they define the rules for shower.

weedmeister- I discussed with my GC and he also proposed the same that I should use recirculation pump so that there is no wastage at all. Most probably we are leaning towards it.

BTW...we ran into a issue with master bed room and the work is paused until structural engineer reviews it. Hence this is on back burner for couple of weeks. Once my hubby makes the final decision will update the post.