In his 41 years with Metropolitan, he made revolutionary changes in the field's understanding of how disinfection by-products occur, are formed and how they can be controlled in drinking water.

[1] He made groundbreaking advances in understanding the watershed sources of pharmaceuticals and personal care products (PPCPs)[2] and wastewater impacts on drinking-water supplies.

[7] In his early career at Metropolitan he developed key advances in the control of tastes and odors in drinking water including analytical methods,[8] sensory analysis[9] and determining sources[10] and treatment of off-flavors.

As Principal Environmental Specialist, Krasner was responsible for the technical direction of DBP research at Metropolitan, as well as studies on the control of other micropollutants of health, regulatory, and aesthetic significance.

He was involved in the design of experimental plans for natural organic matter (NOM), DBP, and PPCP research studies, project management, and interpretation of findings.

Some of his projects included: He made professional contributions to many institutions, including: American Water Works Association (1977 – present), AWWA Research Foundation (now Water Research Foundation, WRF) and American Chemical Society (1975 – present).