Can I use natural gas with a universal fixed-rate invoice for water heaters at a natural gas company?

No.

The universal fixed-rate invoice for water heaters cannot be used to open natural gas in natural gas companies. Because the water heater fixed invoice is an invoice used to purchase the water heater and has nothing to do with natural gas. Invoices or certificates related to natural gas are required to be connected to natural gas.

To open natural gas, applicants need to provide their ID cards and household registers, and fill in the "Resident Customer Information and Gas Ventilation Application Form".