With nearly half its season already over, a US water park has been forced to delay the opening of the world’s tallest water slide for the third time.

Schlitterbahn Waterpark in Kansas City announced on Thursday that Verruckt, a 17-storey, 51-metre-tall water slide, would not open on Sunday as scheduled.

The park’s news release did not give a reason for the latest delay, although earlier this week two media preview days were cancelled because of problems with a conveyor system that hauls 45kg rafts to the top of the slide.

Verruckt, which means “insane” in German, was certified as the world’s tallest water slide in April by Guinness World Records.

The slide sends riders on four-person rafts plummeting at 96-112km/h

Its initial opening date was moved from May 23 to June 5 to allow for more testing, then pushed back again to June 29.

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Schlitterbahn spokeswoman Winter Prosapio said earlier this week that park officials would not hesitate to delay operation for as long it took to make sure the slide was safe.

“We’ll take embarrassment before putting someone in the slide when it is not ready,” she said.

In a news article linked to the news release announcing the latest delay, Schlitterbahn co-owner Jeff Henry told USA Today that he and senior designer John Schooley had based their calculations when designing the slide on roller coasters, but that did not translate well to a water slide such as Verruckt.

In early tests, rafts carrying sandbags flew off the slide, prompting engineers to tear down half of the ride and reconfigure some angles at a cost of $US1 million ($A1.08 million), Henry said.

He said testing was conducted after dark to avoid media helicopters that had been buzzing over the park after hours.