The Environmental Protection Agency (EPA) requires water suppliers to develop and implement a cross-connection control program. Part of a successful program includes surveying water customers in their distribution system to identify and eliminate potential or actual cross-connections that could allow contaminants to flow back into the drinking water from unsafe sources/connections such as fire protection sprinkler systems, boilers, lawn sprinklers and swimming pools.
Sometimes, this survey will be sent regardless of if the water supplier has current inventory of your assembly(s).