The measurements don't even have to be exact.

There was a program that taught women in developing countries to make oral rehydration solution for their children - the result was decreasing deaths due to cholera by an order of magnitude. Many of these women didn't have tools for measuring the ingredients, and the program didn't distribute them - requiring such tools would restrict the spread of the program.

The heuristic is a liter of water, a handful of sugar and a generous pinch of salt. The result may not be exactly the optimal concentration, but it's essentially always close enough to have the desired effect. This heuristic has saved millions (probably tens of millions) of lives.

Right. The formula is for rapid absorption. If you are a little off you will still absorb it eventually. This is a big deal in the ultra running world. You will inevitably dehydrate or get to a bad place unless you learn some electrolyte blend that works well for you. Plain water can work for a short time but most runners will suffer in their later hours (10+).

Thank you for that, I wish more articles would use SI units of measurement.

1l water, 25g sugar, 2.5g salt (approx)

> Thank you for that, I wish more articles would use SI units of measurement.

As someone who only uses traditional units, I wish that more articles would use them. Perhaps a good compromise between us would be for articles to use both!

Recipe ratios in metric: 1 liter water 31 ml sugar 2-1/2 ml salt

Wouldn’t it make more sense to measure the sugar and salts in grams, rather than milliliters?

In fact I think teaspoons are reasonable for those if it's something you'd prepare at home. Faster to measure with a teaspoon than using a scale or measuring cup, I'd think.

I never liked spoon based measurements as the spoon size varies. There’s also the never ending question of level vs heaping.

With those things it doesn't have to be exact. I can imagine how much 6 teaspoons or 2 tablespoons are. But I can't really do anything with 25g without a scale.

I was curious because I sometimes estimate recipe ingredients so I and compared my intuitive notion of a teaspoon and tablespoon to their measured amounts using table salt and found it to be off by a larger margin than I expected.

Different types of salt and sugar have different densities too.

A flat tap is 5 ml isn't it?