The newest Hearth & Horizon story, The Water That Boils Down, turns on one fact: nitrate is a salt, so boiling removes water and leaves it behind. A well at 68 mg/L, boiled until a fifth is gone, reads 68 / 0.8 = 85 mg/L. A formula-fed baby of 3.8 kg drinks about 150 mL per kg a day, 0.57 L, which is 39 mg of nitrate from the well, 48 mg from boiled well water, 28 mg at the 50 mg/L limit and 3 mg from shop water at 5 mg/L.
Boiling is still right for germs. The fix in the story is infant-labelled bottled water for the baby, a laboratory sample for the well, and later a tap filter or a deeper well. A test strip is rough, so the story's assistant will not say the baby is safe or in danger, and it names the warning signs (blue-grey lips, sleepiness, fast breathing) and 112. It is fiction, written by an AI, and not medical advice. Text only, since the audio folder is over its size cap.