Here are two choices for making a home mix rehydration drink:

1. WITH SUGAR AND SALT

One liter of clean water
half of a level teaspoon of salt
8 level teaspoons of sugar
1/2 cup fruit juice, coconut water, or mashed ripe banana, if available

2. WITH POWDERED CEREAL AND SALT

(Powdered rice cereal is best. Or use finely ground corn, wheat flour, sorghum, or cooked and mashed potatoes.)

One liter of water
1/2 teaspoon salt
8 heaping teaspoons (or two handfuls) of powdered cereal
Boil for five to seven minutes to form a liquid gruel or water porridge. Cool the drink and give it to the child. Don't make ahead of time unless you have refrigeration, as it spoils easily.

For both solutions, give the dehydrated person sips of this drink every five minutes, day and night, until he or she begins to urinate normally. A large person needs 3 or more liters a day; a small child usually needs at least 1 liter a day or one glass for each watery stool. Keep giving the drink often in small sips, even if the person vomits. (Not all of the drink will be vomited.)

The book claims that these recipes are "more effective" than the Oral Rehydration Salts packages

I also received the Encyclopedia of Country Living, which is HUGE and has a tremendous amount of useful information, plus sources.

LEARN HEALTHCARE SKILLS NOW

May I suggest Red Cross "First Aid" courses -- usually, these are inexpensive or free. Also, if one is willing to put in about six months of intensive study, an EMT license can be acquired -- EMTs are skilled emergency care personnel (who, incidentally, earn a pretty good living, who can handle health care problems when a doctor or nurse can't be found. These skills are useful, no matter what happens.