Solids handling process design must address a variety of process flows including primary sludge, waste activated sludge, combined undigested sludge, thickened sludge, digester recirculation, and dewatering feed. Activated sludge and primary sludge over 1.5 percent solids and digested sludges over 2 percent solids have non-Newtonian hydraulic characteristics that are fundamentally different than clean water. In these cases, the designer must use alternate hydraulic calculation methods that reflect the non-Newtonian fluid behavior and laminar flow characteristics of sludges. As the many solids streams we manage at water recovery facilities can have highly variable characteristics, transporting the solids can present challenges and requires consideration of unique properties which are impacted by many variables included process configurations, controls and pumping. Therefore, it is critically important to establish criteria, guidelines, and hydraulic calculation requirements for sludge pumping applications and consider the potential for site-specific rheology. Rheology is the study of fluids that focuses on fluid behavior. Mapping the rheological properties of wastewater sludge can be used to inform hydraulic designs and retrofits where solids pumping systems are underperforming. The use of field or laboratory testing to identify site-specific sludge rheology characteristics can be used to ensure performance of solids pumping and handling systems. This presentation describes how evaluation of plant-specific rheology data can improve the approach for analyzing hydraulics of sludge pumping systems and for designing sludge pumping networks. Content includes examples of on-site rheology testing used to optimize sludge pump selection, evaluate fluid property and process design impacts on pump sizing, and troubleshoot failed systems. While methods described in this presentation may be applied to fats, oils, and grease (FOG), municipal scum, paper plant waste, neat polymer, dewatered cake, and other fluids, the focus is on hydraulics of municipal sludge with a solids content of 1.5 to 10 percent with typical pumping applications including primary sludge, waste activated sludge, combined undigested sludge, thickened sludge, digester recirculation, and dewatering feed.