That is what a recirculating hot water system solves. It keeps the water at the faucet or shower hot, if it cools down it recirculates it through the heater until the water is hot again. No water is wasted and it is always hot when you turn on the shower or faucet.

Any good plumber can install it as an after market upgrade. I expect it is less expensive to do it at build time, but either will work.

Running the shower for one minute uses about 2.5 gallons of water and costs about 2 cents, including the sewer charge. I agree that it is wasted water, but the cost is very minimal.

A container? I could fill half a tub of water waiting for the hot water if I didn't have our Watts hot water recirculating pump.That may be a bit of hyperbole.

We have our Watts on a timer too and our hall bathroom and kitchen are connected to the Watts pump. Our timer turns the pump on at 6:00 am and turns off at 10:00 pm. Those are the two water sources farthest from the hot water heater in the garage. Must say though, if you want cold water to drink from the tap, you will wait to clear the line of the hot water.

From what I’ve read this still isn’t for a on demand. Thanks

A check valve (cross over valve) is installed under the master bath sink. A timer is on the recirculating pump can be set in 15 min increments. Amazon.comThe hot water travels thru hot line loops thru to the cold and returns back on cold one to tankless heater. When shower or sink faucet is operated the check valve prevents back flow of cold water to hot water pipe.

A recirculator may save some water cost, but I wonder how much energy you use keeping the circulating water hot because you will lose heat to the ground and air that surrounds the pipes as the water circulates. Cost wise, I'll bet it's a wash in the end.

Elementary, my dear watson
 

The troglodyte

Water
 

I turn on the shower, then undress and lay out clothes. It is hot when I get in.

I brush my teeth with cold water. I can wash my face with cold, or wash my face in the kitchen sink.

I guess accept water down the drain before it gets hot in the shower. The water goes into the sewer, then to the sewage treatment plant, then either goes into the ocean or becomes non-drinking water, e.g., waters crops, etc.

My water bill has not been that much lower when I travel for a month and so do not use the shower or sink.

Everyone can decide what is "worth it" to them - For me, it would be a nice luxury to have hot water very quickly after turning on bathroom taps. However, I do not think it would be worth my spending hundreds of dollars.

Wasted water?
 

How is the water “wasted” if it returns to the Earth’s ecosystem? It isn’t shunted off into outer space. The only waste is the minimal utility fee. That said, waiting is a pain.

This pump works with tankless water heaters. Amazon.com
The warranty on the tankless water heater is reduced if you use a recirculating pump.

What do you need?
 

My wife is in a wheelchair, and I wash her back with hot towels every morning, it's more to relax her muscle than to clean. I used to run the water forever just to get it warm enough. Now I have a large bowl I sit it in the microwave for 5 minutes, I put in the towels and snap on the lid. The towels stay really hot for 15 minutes or more. So, depending on how much water you need this could be a solution.

That's what I do. 2 gallons per shower. Dump it on my robellini. Lol bathrob optional.

Instant How Water
 

Yes, there is a product on the market called Hot Water Lobster.
Hot Water Lobster Intant Hot Water Valve Home Page
It's an instant hot water valve.

I live looonnnggg showers
 

The on demand tankless water heaters save energy/gas at the waste of a little water. Hauling large buckets or tubs of “cold water” isn’t worth my time or within my capabilities.

I step into the shower a little early to get a refreshing cold shower- they say it helps with cardiovascular issues, mental clarity and motivation. Then sit on my shower bench for a very long shower- could be 20-30 minutes enjoying the hot water and the massaging shower spray. I meditate on how grateful to God I am that I have a continuous hot water heater so I can enjoy long showers even when my dishwasher and washing machine are going!!!

And there are soooooo many more dire problems in the world - I am glad i view the water heater as a GREAT THING and provides me moments of peace away from the craziness!!!

Life is too short to stress about the little things - and life is soooooooo wonderful here in The Villages.