The man behind a scheme targeting the eradication of all pests from New Zealand insists it can be done.

Zero Invasive Predators CEO Al Bramley has designed a fenceless barrier system which is maintaining a pest-free peninsula in the Marlborough Sounds.

His aim is to expand the area to eventually take up the entire country in around 40 years time.

Mr Bramley says it's a big ask, but it's possible.

"Everyone thought it was a pipe dream to remove rats from offshore islands. We've now done islands up to 11,000 hectares, those are big islands. It's now time to bring that technology to the mainland."

Al Bramley says creating the barrier is the easy part, but keeping an area pest-free is harder.

He says behind the barrier is a detection system to find invaders or any leakage.

The dairy industry, together with philanthropy organisation NEXT Foundation, and the Department of Conservation are collectively pitching $20 million to the project.