Local governments often pass zoning laws which control what buildings can be built on a lot and what they can be used for. For example, certain areas are zoned for residential buildings such as houses. Other areas can be commercially, agriculturally, or industrially zoned. Sometimes zoning laws establish other restrictions, such as a minimum lot area and/or frontage length for building a house or other building, maximum building size, or minimum setbacks from a lot boundary for building a structure. This is in addition to building codes which must be met. Also, minimum lot sizes and separations must be met when wells and septic systems are used. In urban areas, sewers and water lines often provide service to households. There may also be restrictions based on covenants established by private parties such as the real estate developer. There may be easements for utilities to run water, sewage, electric power, or telephone lines through a lot.