“So pressure is more of an issue over there, though we all know about the circumstance where you’re in the shower and someone turns another tap on in the house and this changes the pressure which changes the temperature so you freeze or boil.”

John is working on a pressure-equalising valve which he believes is the best kept plumbing secret in Australasia. It automatically adjusts both hot and cold pressures instantaneously.

“The pressures may go up or down, but as long as they go up or down together there won’t be a problem with the temperature,” he says.

“It’s a potential solution for problems in sports centres, aged care homes, hotels and motels.”

Greens have also spent about six years developing a special cartridge which is going to be introduced on the world market early next year.

“We have licensed a German company to develop it because of the size of the project,” says John.

“The cartridge will be unique in that it will allow Greens to factory-set the maximum temperature that can ever come out of this tap.

“It doesn’t matter what the temperature is set at within the premises, the water will not come out of the valve at a temperature hotter than the setting on the tap. If the cold water fails, the valve will automatically shut the hot water down.”

Such a safety device would have worldwide potential, and on the 20th anniversary of Greens Tapware setting up in Australia, it is easy to see how big ideas will keep them going for many years to come.