Why is my water bill so expensive?

I used to live in Burbank, CA and my water bill was around $60 for 3 months of water service. Now, I moved to Santa Monica and it's $50 EVERY month. Why is it so much more expensive? Is it possible the water company is making a mistake? There's only 2 of us living in the Santa Monica apt as opposed to 3 in the Burbank apt, and neither of us are using particularly more water than we were in Burbank.