Evidence of septic system failure determined by a bacterial biochemical fingerprinting method

Abstract

Aims: To provide evidence of septic system failure by comparing two faecal indicator bacteria, enterococci and Escherichia coli, from defective septic tanks and adjacent creeks. Methods and Results: A biochemical fingerprinting method was used to type and compare enterococci and E. coli strains from 39 septic tanks with creek water samples. Phenotypic diversity of enterococci (0AE5 ± 0AE3) and E. coli (0AE5 ± 0AE3) in septic tanks were significantly lower than those found in water samples (0AE8 ± 0AE1, P < 0AE0001 for enterococci and 0AE9 ± 0AE1, P < 0AE0001 for E. coli). Among 1072 enterococci isolates tested from septic tanks, 203 biochemical phenotypes (BPTs) were found of which 98 BPTs from 33 septic tanks were identical to several water samples. Similarly, among 621 E. coli isolates tested from septic tanks, 159 BPTs were found of which 53 BPTs from 26 septic tanks were also identical to water samples. The number of the latter bacteria was significantly (P ¼ 0AE01) higher in water samples collected from downstream compared with that of upstream in the study area. A high similarity between the populations of both indicator bacteria was also found between defective septic tanks and downstream water samples further indicating the contamination of both creeks by defective septic systems. Conclusions: Biochemical fingerprinting of faecal indicator bacteria is a useful and rapid method to provide direct evidence for septic system failure. Combination of both faecal indicator bacteria (enterococci and E. coli) provides a better judgement of the performance of a septic system. Significance and Impact of the Study: This study is the first to provide direct evidence of septic system failure by identifying the presence of specific bacterial types in septic tanks and surface waters. Based on our findings, we suggest that the performance evaluation of a septic system should be accompanied by direct analysis of faecal indicator bacteria.

Bacterial Flora of Koi (Anabas testudineus) Harvested from Ponds and Their Antibiogram

“…Free roaming animals and pets especially dogs also contribute to faecal contamination of surface water. Septic system failure, run-off from roads, parking lots and yards can carry animal wastes into natural water and ponds (Ahmed et al, 2005). Birds can also be a significant source of bacteria.…”

Prevalence and Persistence of Escherichia coli Strains with Uropathogenic Virulence Characteristics in Sewage Treatment Plants

“…The prevalence of E. coli in receiving waterways can be due to an array of sources, including domestic and/or wild animals, malfunctioning septic systems, industrial outlets, combined sewer overflows, and wastewater effluents, as well as ineffectively controlled treatment stages and, to an extent, the persistence of bacteria after disinfection (1). The net outcome of the STP treatment process is recycled water with a reduced number of bacteria and, ideally, no pathogens (15).…”

Domestic wells have high probability of pumping septic tank leachate

“…The MCLG-value (Maximum Contaminant Level Goal) of the US EPA for total coliforms and microbial contaminants like Cryptosporidium is less than one per liter (US EPA, 2003b). Particularly in improperly operated drainfields, pathogens can be released in high concentrations (e.g., Alhajjar et al, 1988;Nicosia et al, 2001;Lowe et al, 2003;Ahmed et al, 2005). Even if only a small fraction of the domestic well water originates from septic leachate, such capture is almost certain to carry pathogens, pathogen indicators or low concentration of organic micropollutants such as PhaCs, personal care products, and endocrine-disrupting chemicals, some of which can be transported over long distances (Carrara et al, 2008;Swartz et al, 2006;Godfrey et al, 2007;Rudel et al, 1998;Osenbrück et al, 2007).…”