Introducing: TankVac

Warren Agnew has more than 10 patents for his inventions including the TankVac.


Like many good Kiwi No 8 wire stories, Warren Agnew came up with his latest invention while trying to solve a problem.

One morning, his late wife Lois asked why doesn’t the water tank overflow come from the base, where the old water and leaf material sit, instead of the freshwater from the top. Within an hour, Warren had a simple system working with a 40 gallon drum.

He quickly patented the idea and started a 12-year journey to perfect the system. It included becoming a director of research for the Todd Corporation. This gave him access to Waikato University engineering to help create the design and Auckland University of Technology microbiologist to test the water quality.

The end result is the TankVac, which works by sucking up the materials that accumulate at the bottom of the tank and siphoning them out through a water overflow without the need for power. Warren says this makes the water safer to drink, reduces filter servicing and professional tank cleaning.

It’s one of many inventions and about 10 patents held by Warren, including Gotcha Traps and Black Trakka pest control systems.

The Scotts Landing resident says he has come up with many ideas sitting on his deck staring at his view.

It’s impressive for someone who only started inventing later in life, after a full career as a teacher at primary schools including Warkworth, Matakana and Kaipara Flats.

He doesn’t call himself a scientist, although he studied chemistry and physics at university.

“I tend to just look at problems and try and solve them.”

He credits his creativity to his love of orchestral music. He also has an interest in water quality, including being a founding member of Friends of the Mahurangi River.