Public input is essential to the success of the new building planned at Gainesville’s Riverside Drive water treatment plant, City Council members said Thursday. Council members gave that opinion to public utilities officials after seeing a presentation at the council work session. A resolution to replace, upgrade and move the plant’s chemical systems to a new building is expected to be on the agenda for next week’s meeting, but several members said they don’t want to spend $700,000 on a building design residents dislike.