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Description:This historic 1941 diagram, which had been digitally enhanced and colorized, illustrated a method of altering tank-type flush toilets, in order to prevent "back-siphoning". Back-siphoning is the sudden loss of pressure within a plumbing system that could allow dirty water to be sucked into the supply pipes, which would contaminate the water system's clean water supply. Such a phenomenon could involve just the plumbing in a single house, if it was on its own well, or it could occur inside a municipal water system.
The purpose of these images and the accompanying training was focused on protecting water supplies from bacterial contamination due to incorrect disposal of waste, such as sewage, in order to prevent water-borne diseases. The descriptive information accompanying this drawing referred to a governmental publication, which contained instructions describing how to correctly place and build such a device. The specific citation was, “Minnesota Department of Health, Division of Sanitation, Manual of Water Supply Sanitation, 1938, Section 8, p. 14”.
High Resolution: Click here for hi-resolution image (34.18 MB)
Content Providers(s):CDC/ Minnesota Department of Health, R.N. Barr Library; Librarians Melissa Rethlefsen and Marie Jones
Creation Date:1941
Photo Credit:
Links:Minnesota Health Department
Minnesota Health Department; R.N. Barr Library
CDC – Nat. Center for Infectious Diseases; Water-Related Diseases
CDC Organization
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Copyright Restrictions:None - This image is in the public domain and thus free of any copyright restrictions. As a matter of courtesy we request that the content provider be credited and notified in any public or private usage of this image.