EPI Plastics managing director Norman Woods said the effect was "immediate" as orders for 5-, 10- and 20-litre jerry cans flooded in "within an hour" of the quake on Tuesday last week.
Each container took about 100 seconds to make and the factory was producing more than 1700 a day. It had also attracted new clients.
"We are struggling to keep up with demand," Mr Woods said.
The factory usually operates for 10 hours daily, five days a week. It now runs 24 hours a day, seven days a week, and an employee who was made redundant six months ago has been re-employed.
Mr Woods expected the production increase of "at least 100%" to continue for another month or more.
Although the reason behind the increase in business was "sad", Mr Woods could not help but look on the positive side.
"Like most businesses, we struggle with overdrafts and loans etc, which will be gone for us by next week."
Dunedin-based Quality Bakers had boosted its production almost 50% to meet the needs of Christchurch residents.
Managing director Roger Gray said the bakery was working around the clock, compared with a normal 16-hour day split into two shifts.
"We have been able to shift production from Christchurch to Dunedin as well as Nelson."
The increased production meant 130,000 loaves, buns and other bread products had been baked and sent north in the past week.
Quality Bakers' donations to those affected by the quake and those helping afterwards included 3000 loaves of bread, 300 pallets of pies and pizza and eight pallets of biscuits and cakes, along with 24 pallets of pies and pizzas to the Salvation Army; 2500 loaves to make sandwiches for rescue and Civil Defence workers; about 600 loaves to feed the Student Volunteer Army; 1000 loaves to the Rangiora Earthquake Express, which provided meals to families in the worst-affected suburbs; and 100 loaves to the Hohepa Trust, which cares for the disabled.
