One commenter, Marvin Jones, wrote: "I'm guessing the councillors will draw straws as to which one will wade in during a storm to open it manually."
Another, Zylph Gold, suggested a gate shaped like a duck's beak that released stormwater but was forced shut by waves.
Larry Dalimore said the "massive structure" was working well as a city attraction. "We have a drain underneath with obvious problems because it's built at high-tide level and located in the middle of a beach," he said. "The real interest is how will it be protected and how the backflow gate will work. Can someone at Napier City Council explain?"
Mr Dalton said that he was reluctant to enter the discussion "because of the number of pathetic and irrational anti-NCC comments", but "in the hope that some are genuinely interested in progress in our city, here are some facts".
"The pipe under the viewing platform is not yet connected to the Napier stormwater system. Therefore it has no outflow to assist in clearing the pipe," he said.
"With any such outfall into the sea, there is a degree of experimentation to achieve the final and long-term solution. One possible solution is a right-angled exit pipe heading north. We will fine tune the final exit point and end up with one that works."
Council CEO Wayne Jack told Hawke's Bay Today the outfall pipe was designed to operate with the end gate closed.
"The end gate is intended to provide access for periodic maintenance and does not need to be lifted with every rainfall event," he said.
"The outfall operates by discharging storm flow via openings on the sides of the culvert, located at a level that will enable gravity discharge in significant storm events.
"To build a longer outfall structure at this time would have been prohibitively expensive due to the challenging nature of the site and significant associated construction costs and would have provided no additional operational benefit."
He said it was "a difficult environment" and any design would face similar challenges, complicated further by low ground levels inland.
The viewing platform cost $716,000 and the outflow pipe $684,000, from a $2.4 million budget central business district stormwater upgrade.
Many took to social media to voice disappointment that it was not a pier extending into the ocean.