it's a water leak on the side of the meter that is yours. and wasted
water isn't free. if you're the homeowner you need to call a plumber.
if you're a tenant you need to notify the landlord to call a plumber.
call your water meter reading into the water company and ask how much
usage you have since the last reading. match your water bill to a
neighbor's. the difference in dollars will move you to call a plumber
promptly. if the usage is similar then you have caught the problem
early.

on the odd chance that you've encountered a subterranean alien source
of free heat we'll all be wanting your address for free samples.