Many bulk storage tanks do not yet have independent overfill protection, and a common problem at brownfield sites is that there are no nozzles available for adding a high level alarm sensor. Mechanical modifications like adding tank openings may be prohibited due to cost and time constraints - especially if requiring an additional still-pipe, e.g. for a floating roof tank. Advancements in radar technology has created a 2-in-1 radar gauge that elegantly solves this problem. 2-in-1 radar level gauges can be used simultaneously for automatic tank gauging and independent safety level measurement, while using only one tank opening. The transmitter housing contains two separate radar level units that are galvanically separated and fully independent. This new solution has been verified by independent accredited third parties to be compliant with both IEC 61511 and API 2350, and the Rosemont 5900S 2-in-1 Radar Level Gauge is SIL3 and SIL2 certified according to the IEC 61508 standard.