Hundreds of businesses affected by the ruptured Maui pipeline had their gas supplies restored on Sunday.
Vector, which operates the pipeline, says overnight tests confirmed the pipe has been repaired and it was reopened on Sunday morning.
The tests included x-rays of the damaged section.
A crack in the pipe in northern Taranaki was found last week causing thousands of businesses in the upper North Island to be cut off from the gas supply on Tuesday.
The pipe was repressurised on Sunday morning and Vector says gas supplies were restored to the remaining 500 affected customers.
Vector says the section of pipe where the crack was discovered will be monitored over the next couple of weeks to ensure there are no future leaks.
Acting Minister of Energy and Resources Hekia Parata says there will be an incident report and a formal industry-led review, as required by regulations.
Vector chief executive Simon Mackenzie says the review particularly needs to look at contingency plans.
He says the focus until now has been on getting the pipeline running again but there are always lessons to be learnt.
The review will also consider the merits of building another pipeline.
But Mr Mackenzie says building a duplicate would involve a huge economic trade-off, and cost.
Many manufacturers were forced to shut production because of the broken pipe, leading to shortages in supermarkets including of dairy, bread and beer products.
Fonterra was among the worst affected companies, temporarily closing 15 of its milk processing plants and leaving farmers no choice but to dump fresh milk.