Which type of homes may have elevated indoor radon levels due to radon in water transport?

The correct answer is derived from the nature of radon transport and its presence in groundwater. Homes served by private, drilled wells can experience elevated indoor radon levels because radon can dissolve in groundwater sourced from underground rock formations that contain uranium, the parent material of radon. When water from these wells is used in daily activities like showering or cooking, it can release radon gas into the indoor air, potentially increasing radon levels inside the home.

Homes served by municipal water supply typically undergo treatment processes that can reduce radon content before the water reaches consumers. Basements may influence radon levels due to soil gas intrusion but do not specifically relate to water transport of radon. Meanwhile, homes located in urban areas might not have elevated levels of radon from water unless they particularly rely on private wells, which is not common in urban settings. Therefore, homes served by private, drilled wells are particularly vulnerable to issues associated with radon in water transport.