How Much Is Your Leaky Faucet Costing You?  On average, a 
leaking faucet will cost around $20 per month. A leaky toilet, 
another common example, is around $150 per month on average!

The United States Geological Survey has a comprehensive drip calculator designed to give you an estimate of how much water you are wasting annually due to plumbing leaks. So:

One gallon = 15,140 drips
One liter = 4,000 drips
Say you have a relatively slow-dripping faucet – a typical rate of 10 drips per minute – then you’re wasting three liters of water per day. That is 90 liters per month, or 347 gallons of water each year.

Now, a faster drip is, say, 21 liters of water each day. That amount wasted adds up to about 2,082 gallons of water each year. Or, 5 gallons every single day. That is a lot of water being wasted. That amount only takes into consideration a leaking faucet. What about a leaking shower head or pipe? You could be wasting thousands of gallons of water every year.