Thieves in the last three weeks have hit scores of city park bathrooms and made off with a valuable commodity: $10,000 worth of brass toilet flush valves.

City officials asked the public yesterday for help in finding the stolen parts, which police said could end up in a black market for construction parts or melted and sold for metal.

Construction materials and industrial supplies are sometimes stolen from job sites and new housing developments, police say, but rarely from public restrooms.

In addition to the valves, which cost taxpayers $100 apiece, police say the thieves made off with toilets, sinks and other items from 28 city parks located on the North Shore and in Central O'ahu.

City Parks and Recreation Director Lester Chang said repairs will be expensive.

Chang said the costs go beyond the value of the valves, because of the labor to replace them and the hidden cost of other work not being done because crews will be busy with repairing the toilets.

"The worst part of this is the inconvenience to the park users," he said.

Two detectives are on the case, police said. No suspects or leads have been identified.

"It's taxpayers' dollars and we take all crimes seriously," said police spokesman Capt. Frank Fujii.

Roughly three weeks ago, police began receiving reports of thefts from public restrooms in North Shore parks. Some bathrooms were fleeced clean, police said, while others were just missing the valves.

The industrial toilet flush valves cannot be used with standard residential toilets.

Construction workers and contractors have been known to loot the job sites of competitors but the theft of bathroom materials is unheard of, police said.

Park vandalism is usually an isolated incident, not a rash targeting the same piece of equipment.

Chang said the thief or thieves often work at night and usually remove all of the valves in a park restroom. Sometimes, up to a dozen disappear over a weekend, he said.

Chang said parks crews believe the thieves are likely selling the valves for the metal or stealing them for a building project.

"Who could guess why they'd want it?" he asked. "If we could have figured it out, we'd have solved it already."

Reach Peter Boylan at pboylan@honoluluadvertiser.com and Robbie Dingeman at rdingeman@honoluluadvertiser.com.