Petrol is a highly flammable, explosive and toxic substance. There are laws you must obey and rules you need to follow if you are storing it.
It's against the law to store more than 20 litres of petrol in two 10 litre metal containers, and 10 litres in two 5 litre plastic containers. All containers must be designed for the purpose and they must be marked petroleum and highly flammable.
Apart from what's in the fuel tank, you can only transport petrol in securely closed containers designed for the purpose and marked petroleum and highly flammable. Make sure they are secured in the boot when being transported.
Filling your tank from a container should only be carried out in the open air.
Store any containers in a garage or shed away from any other buildings. Don't keep it in the house. Make sure the area is well ventilated and away from any naked flame or live electrical equipment.
Check containers regularly for leaks. If you smell petrol fumes, ventilate the area and make sure nobody smokes or turns electrical switches on or off. The slightest spark could cause an explosion.