What is the best temperature for a water heater both to save energy and with a young child in the house?

Anything much over 104F (40C) is probably too hot with a child in the house.
That is simply my opinion, Chances are you might be able to have it hotter without scalding but I know this temperature is safe.

It will mean you will have to not run the water in the shower while soaping up or lathering because you will be using almost straight “hot” water and you will use the “hot: stuff up before you are done if you leave it running. This change of habit will save you money on water/sewer and on the energy to heat the water.

Even with a toddler in the house, its never too early to set firm rules such as “Don’t turn on the bathtub by yourself” also teach your child, once they can reach the sink, how to adjust the water correctly. If they do get scalded, it will probably be the last time.

I guess I come from a family where my parents let me make me own mistakes. They also took my hand so close to a hot stove and would say “Hot! Don’t touch”

@Rememberme : It is my opinion that toddlers are not able to figure out water temperatures, and allowing a child to get scolded so that they will learn the water is hot is not an acceptable way to raise a child. Older children can make this distinction, but not babies or toddlers. The temperature of hot water is still hot, even when lowered, and children will still need supervision so they won’t get hurt.

Many come from families where parents let children make their “own mistakes,” such as your example with the stove. However, in my book, such parenting decisions are poor ones, and I hope that those who have been so treated will be able to see (and understand) what was done to them and not repeat these behaviors with their own vulnerable children. Our children deserve better.

@Skfinkel I want to make it clear that It is very important to supervise children. Of course safety should be a top priority. I would also make it clear that by scalding I do not mean burning. I mean scalding in the sense that it is too hot to touch for an extended period of time. I also do not mean for a child to draw their own bath at such a young age. A more likely scenario would be when a child can reach the sink and turns the water on hot (without anyone supervising) then the child may scold themselves. That is what I mean by the child making their own mistakes.

Don’t under estimate the intelligences of a toddler. That is a period of development where they are learning so much (even when you get a glazed over look in their eyes, they still downloading the world around them). Actually one good exercise for preschoolers is taking a large empty bowl, one small bowl of hot (but not too hot!) water, and one small bowl of icecube water. Then allowing the child to play with the water, mixing it together.

Sorry, I saw this in “Related”.

I just got a new electric hot water heater and it was preset to 120°, which appears to be the “We can’t be sued here!” temperature.

Not nearly warm enough for me, but apparently safe for all.
(I ended up at about 132° and it’s still a little warm.)