Web warehouse provides high availability and efficiency by utilizing materialized webviews, which should be refreshed in time to keep freshness. During the refreshing, the consistency between a webview and its base data, which is formally named single view consistency (abbreviated as SVC), must be guaranteed. Since the base data changes in a web warehousing environment do not propagate from data sources to the information consumers, which is far different from the case in the traditional data warehouses, we must pursue new maintenance methods. In this paper we first introduce the definition for SVC, and then we present an algorithm RCA to keep SVC as well as an effective base data change detection method SAA. We illustrate that RCA and SAA can guarantee SVC and they are effective in the web environment.