For a more rigorous test of the accuracy of our DLPNO-CCSD(T) implementation, we consider some of the larger systems for which canonical CCSD(T) results are available: conformers of (H 2 O) 16 and (H 2 O) 17 , in the aug-cc-pVTZ basis, from the work of Xantheas and coworkers. In their work, they computed canonical CCSD(T) reference values using supercomputing resources at the massive ORNL Leadership Computing Facility. They used the CRAY XT5 partition, containing a total of 18,684 compute nodes and 224,208 processing cores with more than 300 TB of memory. In contrast, all of our computations were run on a single computing node with 32 CPU cores and 450 GB of RAM. and the other contributions are treated with MP2. We will refer to that as "3b:mb" as shorthand.