Book sale convener Don Gilbertson said the downpour was too much for the internal gutters of the building at 39 Taupo Quay and, when they arrived yesterday, some of the boxes of books were sitting in water.
Mr Gilbertson said only the bottom two books in the boxes were wet and they managed to save all the top books.
Boxes of puzzles that were in plastic bags were saved and would dry out.
They were, however, thankful to Ross Mitchell-Anyon for his "civic mind". He had let Rotary use the building for the past two years for the sale.
Flyers were put out to the general public, and the books had started to trickle in over the past year.
From December onwards there was a big push for more.
St John also gave books left over from their annual book sale and Rotary gave a donation in return.
Mr Gilberston said the Wanganui Rotarians raised funds for a number of projects locally.
They supported two students to get to the summer science schools at Auckland University.
"It costs $1500 for each student for the two weeks."
Funds also helped Wanganui families who hosted overseas exchange students, students to attend the Rotary Youth Leadership Awards and students to get to Outward Bound.
They had planted 1.5km of trees around Springvale Park; along the Carlton Ave extension, the London/Parsons streets perimeter, and heritage fruit trees near the former St George's School.
Mr Gilberston said the Rotary polio scheme worldwide had almost eliminated polio with only two cases reported last year in India.
The Rotary Club Wanganui book sale, 39 Taupo Quay, Saturday 9am-4pm, Sunday 10am-3pm.
