Invercargill's new hydroslides lost more than $11,000 in the first 15 weeks due to closures and discounts.

But that's a drop in the ocean compared to what Covid-19 lockdown is costing the council overall - as much as $750,000 a month.

Splash Palace opened the three new water slides back on April 19.

They've been a hit with the public, with about 1,300 people sliding down them on average each week, to August 3.

Advertisement: Reading Cinema

Financially, however, they've yet to provide the return expected, after being dogged by teething issues.

The slides cost $81,795 to run in that 15-week period, which includes the costs of staffing, electricity, chemicals, depreciation and loan repayments on the $3.2 million build cost.

They generated $70,554 in revenue.

One of the main issues has been the closure of the two body slides and then the raft slide.

Advertisement: Freedom Companion Driving

The two body slides, measuring 69m and 79m and coloured green and blue, were closed for a week from June 28, so contractors could grind and build up a number of joints to align them for better slide experience.

That led to a 60% discount for customers. The contactors also spotted a defect on one of the structural columns of the 101-metre red and yellow raft slide, which had shifted a couple of millimetres at the top.

When they told the Aquatic Services Manager, a week later on July 8, the slide was closed within minutes and has remained closed since. Repair work should, however, be completed by the end of this month.

"This issue has not impacted in the safe operation of the other two body slides, but the impact of closing the most popular ride has understandably had an impact on participation numbers using the slide and likely also wider visitation to the facility as well as an impact upon expected revenue," a report to the council's infrastructure committee reads.

Advertisement: First in Windsor

"During the two weeks of the July school holidays alone it was estimated that due to the closure of the raft slide there was a potential loss of revenue of $24,637."

The closure led to a 30% discount, while all slides were discounted 60% during the first four weeks as an opening offer. All in all, they were discounted 50% over the 15 weeks.

It's not all bad news for the hydroslides, however.

Without discounts and closures, in the first 15 weeks they would have taken a revenue of $136,829.

Advertisement: Factory 2 Hair & Home

That's a $55k profit, although the report writer notes there could have been fewer users without the discounts.

There's no information in the report on who picks up the bill for the repairs.

It does reveal, however, that the closure of all facilities during alert levels 3 and 4 is costing Invercargill City Council between $500,000 and $750,000 a month in lost revenue.