Aucklanders are being warned against stockpiling petrol - a day after the Regional Fuel Tax kicked in.

The Environmental Protection Agency has been sent videos of people filling unapproved containers to the brim before prices rose 11.5 cents a litre.

EPA says people might not realise the risks they're introducing to their home and family.

Hazardous Substances Group general manager Dr Fiona Thomson-Carter says petrol can easily catch fire or explode - and you can also get sick from breathing in petrol fumes

Legally people can store up to 50 litres of petrol at home in pre-approved containers which are tested and certified.