AbstractHot tub lung (HTL) is a pulmonary disease where a hypersensitivity pneumonitis is caused by exposure and inhalation of aerosolized non‐tuberculous mycobacteria (NTM) traditionally from hot water steam. HTL can affect both immunocompromised and healthy individuals, and diagnosis is dependent on high clinical suspicion in conjunction with high‐resolution computed tomography (HRCT) and microbiological evidence. We present, to our knowledge, the only case of HTL occurring from an indoor swimming pool affecting five members of a family, in which one member was not a resident of the household.