Why do technologists send off water samples to a lab to be measured instead of performing the tests themselves

Question

Why do technologists send off water samples to a lab to be measured instead of performing the tests themselves

Answer 1

Because a lab can carry out tests under more controlled conditions than can be done in the field.

Answer 2

A lot of these tests use very expensive and specialized equipment.  Most small labs (or sampling companies) don't have the advanced equipment required for some of these tests, so they send them off to a specialized lab that has the appropriate equipment.

Another reason is that the technologists may not have proper training in the water sampling techniques.  The big labs with special equipment will have trained technicians that can conduct the tests.