Houses are normally connected to local utilities, such as mains water, electricity and gas supply. In the countryside, not everyone is connected to mains gas, and some houses have gas tanks in their gardens. The vast majority of people are connected to the local sewage system (for waste water), but some people have their own septic tanks in their gardens to treat waste water. Houses that are connected to utilities have separate meters to show how much they consume. Representatives of these utility companies visit houses regularly to take meter readings – with which they can then bill their customers.