An investigation conducted by the agency found that the woman had not recently been exposed to fresh water but had performed the nasal irrigation using non-boiled water from the RV's potable water faucet "on several occasions" before her illness.
The potable water tank, the investigation found, was filled before the woman bought the RV three months ago and could have contained contaminated water. The investigation also concluded that the municipal water system, which was connected to the potable water system and bypassed the tank, could have caused the contamination.
A bit misleading to put so definitely "tap water" in the headline when this was 3 month old RV water.