Do you have any idea where your main water supply shutoff is located? Many homeowners do not, and this is a problem. Why is that? Well, imagine that you have a broken water pipe somewhere in your home. You try to stop the water, but it just keeps gushing out, so you go looking for a shutoff valve, only to realize there is none nearby.
At this point, you would need to turn off the main water supply until you can fix this leak, but if you don’t know where it is, you are looking at some very expensive water damage to your home.
This is why you want to be aware of where the main water supply shutoff valve is located. To find it, you want to start looking where the water enters your home. Your water heater is a good starting point, and from there you should be able to trace the water back to its source. You might find a valve there that can be used to shut off water to your home, but in some cases, there might be a hatch in your front yard under which there is a valve. To operate this, you most likely will need a meter key.