: Data warehousing is the process of constructing of data. A data warehouse is constructed by integrating data from multiple heterogeneous sources that support analytical reporting, structured and/or ad hoc queries, and decision making. There is one key obstacle to the rapid development and implementation of quality data warehouses specifically that of warehouse data quality issues at various stages of data warehousing. Specifically, problems arise in populating a warehouse with quality data. The problems arise in populating a warehouse with quality data.Morever the period of time many researchers have contributed to the data quality issues, but yet we didn’t identify the causes of data quality problems at all the phases of data warehousing Viz. 1) data sources, 2) data integration &amp; data profiling, 3) Data staging and ETL, 4) data warehouse modelling &amp; schema design. The purpose of the paper is to identify the reasons for data deficiencies, non-availability or reach ability problems at all the above mentioned stages of data warehousing and to give some classification of these causes as well as solution for improving data quality through Statistical Process Control (SPC), Quality engineering management.