# A thought on plumbing, water wasted

1. Jul 19, 2011

### Newai

Waiting for the water to warm up means letting the shower/sink faucet run for a while, especially in this apartment building. So, how about a valve just above the tank that sends that water in the line back into a reservoir, which can be released back into the tank?

2. Jul 19, 2011

### zoobyshoe

Good idea.

3. Jul 19, 2011

### Staff: Mentor

That's typically done in apartment buildings - it kinda has to be since otherwise it would take forever to get hot water. It requires a pump though, and for houses the energy loss of the pump and heat loss in the pipes that are always hot would cancel out the  saved in water.

4. Jul 19, 2011

### lincs-b

This is a good idea.
People always talk about reusing grey water from baths and showers. I always thought it would be a good idea to channel it to a water butt outside of my house. When I did some research I found that the water could only be stored for about a day without treating it so I don't think it is such a good idea after all.

5. Jul 19, 2011

### Newai

A pump for what? I mean using a valve right above the tank to release the water already in the line from the tank to the faucet/shower head back into a reservoir that could return the water back into the tank.

6. Jul 19, 2011

### Chi Meson

Last edited: Jul 19, 2011
7. Jul 19, 2011

### Newai

But that's a pump that requires electricity. My suggestion is strictly mechanical/nonelectrical.

8. Jul 19, 2011

### Newai

I thought that was water intended for the toilet. Given how often most places will have the toilet used, you shouldn't need to store it for more than a day.

9. Jul 19, 2011

### Chi Meson

Well, that's simply not going to work. The water in the tank is about 60 psi greater than atmospheric pressure. That's the reason it comes out when you open the faucet. A difference in pressure is needed to cause water to flow. If you let the faucet run until the water got hot, then that water is now at ATM, and it can't funnel back into the tank without be pressurized.

I can't tell if this is the system I heard of before, but the real water to save is the hot water that is in your pipes after you turn off the faucet. At this point the pump pushes that hot water back into the tank. Since this hot water is pushed by the equally pressured cold water, very little force/energy is needed to do this pumping.

Much more energy is saved by not letting that heat leak into your house walls, compare to the energy used by the pump.

10. Jul 19, 2011

### Newai

Hmm. Okay, thanks for clearing that up.

11. Jul 19, 2011

### Staff: Mentor

Domestic water systems don't have air in them so you can't just "release" the water and let it fall. The entire system is always pressurized, otherwise water wouldn't flow up the pipes in the first place.

12. Jul 19, 2011

### Staff: Mentor

The downside of not having a dedicated return is that now your cold water pipes contain warm water.

13. Jul 19, 2011

### lincs-b

It can be used for gardening as well, my idea was for it to collect in a rain butt type container out side of the house. There would be no need for a pump then.
So much water gets wasted by burst pipes any idea would have to save a household money rather than being concerned with saving a small amount of water.

14. Jul 19, 2011

### Chi Meson

The original system that I heard of about 2 years ago did have a 3rd pipe to allow the "pre-runoff" to go back to the tank. When the temp reached about 5 degrees of the expected "hot" temp, the water would flow from the faucet, and when the faucet was turned off, cold water pushed the hot back to the tank.

I considered installing this system, but I already have a rather efficient short-run to most of my taps, and I installed a 4-gallon "point-of-use" mini-tank in my kitchen.

In general, I highly recommend the POU heaters, both tankless and minitank, for your far-reaching faucets.