Trump inspected the first Boeing 787-10 when it rolled of the line in Charleston.
https://www.usatoday.com/story/travel/flights/todayinthesky/2017/02/17/trump-boeing-unveils-newest-biggest-dreamliner-yet-787/98056802/
The water tanks are installed on the main cabin deck during testing and evaluation to simulate passenger weight.
The tanks are removed and replaced with passenger seats prior to delivery.