Hearth & Horizon has a new story, Boil It Once, about 3,600 words, text only for now. After a flood in an invented Hungarian village in 2047 the well tests positive for bacteria, and the water assistant sends the standard notice: boil for five minutes. Then it reads the other line in the same lab file: nitrate at 58 mg/L against a limit of 50.
Boiling takes the water away and leaves the nitrate. On a 0.8 kW ring with the lid off, five minutes of rolling boil loses about 11 percent of a litre (240 kJ against 2,257 kJ per kg), so 58 becomes about 65. Twenty minutes loses about 42 percent and gives about 100. A grandmother doing her best for a seven-week-old granddaughter has been making bottles at twice the limit. A covered kettle that switches itself off loses under 2 percent.
The assistant has to correct its own notice, and its first rewrite ("everyone use bottled water") is refused by the district nurse because it would empty the village shop and leave the old without safe water. The final notice is split: boil once for everyone, bottled infant water for the nine babies under six months, in numbers anyone can check.
What is real: nitrate is not removed by boiling, the 50 mg/L limit, and methaemoglobinaemia in young bottle-fed babies. What is invented: the village, the people, the well's readings. It is fiction, not water-safety advice.