WHO and UNICEF jointly have developed official guidelines for the manufacture of oral rehydration solution and the oral rehydration salts used to make it (both often abbreviated as ORS).
They also describe acceptable alternative preparations, depending on material availability.
Commercial preparations are available as either pre-prepared fluids or packets of oral rehydration salts ready for mixing with water.

The formula for the WHO oral rehydration solution (also known as low-osmolar ORS or reduced-osmolarity ORS) is 2.6 grams (0.092 oz) salt (NaCl), 2.9 grams (0.10 oz) trisodium citrate dihydrate (C
₆H
₅Na
₃O
₇⋅2H
₂O), 1.5 grams (0.053 oz) potassium chloride (KCl), 13.5 grams (0.48 oz) anhydrous glucose (C
₆H
₁₂O
₆) per litre of fluid.
This is 44 mmol salt, 10 mmol trisodium citrate dihydrate, 20 mmol potassium chloride, and 75 mmol anhydrous glucose per litre.
This would have a total osmolarity of (44×2 + 10×4 + 20×2 + 75) = 243 mOsm/L.
A basic oral rehydration therapy solution can also be prepared when packets of oral rehydration salts are not available.
The molar ratio of sugar to salt should be 1:1 and the solution should not be hyperosmolar.
The Rehydration Project states, "Making the mixture a little diluted (with more than 1 litre of clean water) is not harmful."

The optimal fluid for preparing oral rehydration solution is clean water.
However, if this is not available, the usually available water should be used.
Oral rehydration solution should not  be withheld simply because the available water is potentially unsafe; rehydration takes precedence.

When oral rehydration salts packets and suitable teaspoons for measuring sugar and salt are not available, the WHO has recommended that homemade gruels, soups, etc.,
may be considered to help maintain hydration.
A Lancet review in 2013 emphasized the need for more research on appropriate home made fluids to prevent dehydration.
Sports drinks are not optimal oral rehydration solutions, but they can be used if optimal choices are not available.
They should not be withheld for lack of better options; again, rehydration takes precedence.
But they are not replacements for oral rehydration solutions in nonemergency situations.
WHO and UNICEF jointly have developed official guidelines for the manufacture of oral rehydration solution and the oral rehydration salts used to make it (both often abbreviated as ORS). They also describe acceptable alternative preparations, depending on material availability. Commercial preparations are available as either pre-prepared fluids or packets of oral rehydration salts ready for mixing with water.
The formula for the WHO oral rehydration solution (also known as low-osmolar ORS or reduced-osmolarity ORS) is 2.6 grams (0.092 oz) salt (NaCl), 2.9 grams (0.10 oz) trisodium citrate dihydrate (C
₆H
₅Na
₃O
₇⋅2H
₂O), 1.5 grams (0.053 oz) potassium chloride (KCl), 13.5 grams (0.48 oz) anhydrous glucose (C
₆H
₁₂O
₆) per litre of fluid. This is 44 mmol salt, 10 mmol trisodium citrate dihydrate, 20 mmol potassium chloride, and 75 mmol anhydrous glucose per litre. This would have a total osmolarity of (44×2 + 10×4 + 20×2 + 75) = 243 mOsm/L.
A basic oral rehydration therapy solution can also be prepared when packets of oral rehydration salts are not available. The molar ratio of sugar to salt should be 1:1 and the solution should not be hyperosmolar. The Rehydration Project states, "Making the mixture a little diluted (with more than 1 litre of clean water) is not harmful."
The optimal fluid for preparing oral rehydration solution is clean water. However, if this is not available, the usually available water should be used. Oral rehydration solution should not  be withheld simply because the available water is potentially unsafe; rehydration takes precedence.
When oral rehydration salts packets and suitable teaspoons for measuring sugar and salt are not available, the WHO has recommended that homemade gruels, soups, etc., may be considered to help maintain hydration. A Lancet review in 2013 emphasized the need for more research on appropriate home made fluids to prevent dehydration. Sports drinks are not optimal oral rehydration solutions, but they can be used if optimal choices are not available. They should not be withheld for lack of better options; again, rehydration takes precedence. But they are not replacements for oral rehydration solutions in nonemergency situations.
Oral rehydration therapy