157 is a little better than average TDS which is around 250 nationwide.
Its certainly not something I would put in my reef tanks but depending on hwta the 157 is made up of its probably fine for drinking. Thats the problem with TDS, its a measurement of everything electrically conductive in the water so does not speciate or identify anything in particular. It could be calcium and magnesium or it could be phosphates, silicates, nitrates, copper, iron or any number of other things.

The beauty of a RO/DI system is it removes everything and is not selective so a reading of 0 TDS means you eliminated it all and are starting with fresh pure water again.