SEPTIC TANK STUDIES 



17 



Table 9. — Results of Fermentation Tests From Table 7. Expressed 

 AS Percentages of Number of Tests Made. 



*False positive tests produced by bacteria not of the coliform group. 



Note: South tank, normal 24 hours retention; middle tank, 12 hours retention; north tank, 8 

 hours retention. Controls were soils from the same area that had not received sewage effluent. 



Table 10. — Analysis of Positive Coliform Tests of Table 8, Expressed 

 as Percentages of Number of Coliform Cultures Recovered. 



Note: South tank, normal 24 hours retention; middle tank, 12 hours retention; north tank, 8 

 hours retention. Controls were soils from the same area that had not received sewage effluent. 



