A young Auckland family is the second winner of Lotto's $25 million jackpot Powerball - after initially thinking they'd only won $25,000.

When the enormity of the win sank in they celebrated with pizzas.

The winner said they saw an email in their inbox from Lotto NZ but "didn't think much of it".

"I was checking my emails in the lounge on Sunday morning and saw I had one from MyLotto Customer Support saying I'd won a prize. I logged on to the app on the iPad to check my ticket," the winner said today in a statement.

"I watched as the numbers were circled on my ticket one by one. Then some quite large numbers popped up across the top. I must have shouted pretty loud when I saw them as my Dad came running in."

The winner's father said he heard the shriek and went to check it out.

"I got to the lounge – and just heard 'Dad, I think I've won $25,000.' When I peered at the ticket, I saw there few more numbers than that," he laughed.

The winner then told her mum the news. "I thought something terrible had happened, as there were lots of tears. I just kept saying 'what's wrong, what's wrong?' said the winner's Mum.

"I'm a millionaire!", she said through tears.

The family celebrated their mega-win with pizzas and say they are still in shock.

"It's still hard to believe - things like this don't happen to people like us."

The ticket was purchased online via MyLotto and the winner said the purchase was prompted by the large jackpot at stake.

"When I saw it was $50 million and had to be won, I knew we had to grab a ticket."

The winner said they want to pay off the mortgage and other bits and pieces, but wanted to think long-term.

"The main thing for us is setting up this money so many generations benefit – our children, their children and so on. It can do so much for our family's future.

The winner said they wanted to invest the money wisely, and not let it get to their heads.

"I was brought up with good morals and values and it's important to us that our children are raised the same way.

"Although this money is an amazing opportunity and can change our lives massively, I still want our children to understand the value of a dollar."