The game's appeal is the same as its risk: games run to 11, sides change fast, and the next match starts before the last one cools down. Two hours of doubles on a fall morning — cool air, active court — loses real fluid through sweat and breath, and the sideline culture of "one more game" skips the water stop. The measured rule is the interval standard from sports science: a few ounces every side change and a full bottle between games, treating the rotation as the break schedule rather than waiting for the session to end. The post-match beer or sports drink is fine as a reward; the water before and between games is the fluid that matters.
| Food | Oxalate (mg) | Serving | Rating |
|---|---|---|---|
| Water, still | 0 mg | 1 bottle | Safe |
| Coconut water | 14 mg | 1 cup | Safe |
| Banana | 6 mg | 1 medium | Safe |
| Orange slices | 2 mg | 1 wedge | Safe |
| Pretzels | 4 mg | 1 oz | Safe |
The court-side classics are stone-friendly with portions in mind: a banana at 6 mg and orange slices at 2 mg are the low-oxalate refuel, and coconut water at 14 mg per cup still sits Safe while adding potassium. The electrolyte drink question is the one the trials answered — a 2009 crossover study found a sports drink raised urinary sodium but left calcium unchanged, no net stone-risk change. The measured habit is water as the base, the banana or orange at the sideline, and the electrolyte drink reserved for the long sessions where it earns its place.
Three habits cover most of the upside. Hydrate on the rotation, not the finish — a few ounces every side change keeps the urine volume steady through a two-hour session. Keep the sideline fuel low-oxalate: banana and orange slices are the classic and the measured amounts sit Safe. And let the session length set the drink plan — under an hour, water is enough; the longer doubles marathon earns an electrolyte drink, not the other way around.
See how oxalate values are measured and verified on our data methodology page.