Hi all…information on fungi in drinking water distribution systems continues to be scarce.  As far as I am aware, there are no guidelines or regulations anywhere and it remains unclear as to whether or not their presence is necessarily indicative of a risk to human health. In a recent study (below) the authors report that 75% of the samples in two Columbian drinking water network and individual household plumbing aqueous and biofilm samples were positive for fungi. Some of the cultures isolated produced mycotoxins which were identified to be cytotoxic and genotoxic. They also found that the fungi produced volatile organic compounds (phenols, alcohols, alkenes, monoterpenes, aldehydes and alkanes) which can contribute to taste/odour or react with chlorine to form DBPs. Both treatment plants were conventional (i.e. flocculation, settling, filtration, and hypochlorite sodium chlorination-free chlorine ranged from 0.5 and 1.5 mg Cl/L in the distribution system).

I coincidentally came across another about to be published paper in the Journal of Water and Health entitled “Domestic shower hose biofilms contain fungal species capable of causing opportunistic infection” which is described as the “first detailed analysis of fungal populations in shower systems and revealed the presence of sequences related to Exophiala mesophila, Fusarium fujikuroi and Malassezia restricta. These organisms can be associated with the environment and healthy skin, but also with infection in compromised and immuno-competent hosts.”) http://jwh.iwaponline.com/content/early/2016/04/06/wh.2016.297

It seems more research into the topic is warranted.

Bill

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Fungi in biofilms of drinking water network: occurrence, diversity and mycotoxins approach

  1. Hurtado-McCormick, L. Sanchez, J. Martínez, C. Calderón, D. Calvo, D. Narvaez, M. Lemus, H. Groot and M. Rodríguez Susa

Water Science & Technology: Water Supply

http://ws.iwaponline.com/content/early/2016/02/24/ws.2016.024

http://ws.iwaponline.com/content/ppiwawstws/early/2016/02/24/ws.2016.024.full.pdf

ABSTRACT

“Results showed that 75% of the analyzed samples in drinking water network were positive for fungi, into a range of 1–3,000 CFU/mL. Identification resulted in 9 species of fungi and 4 species of yeasts: Bjerkandera, Penicillium, Paraconiothyrium, Paecilomyces, Debaryomyces, Rhodotorula and Cryptococcus. Although yeasts showed higher traceability than filamentous fungi, the fungal genus Penicillium had relevance by both traceability (6 species) and by its role in mycotoxins generation. From VOC mycotoxins extracts analysis from P. ochrochloron and P Purpurogenum water – M9 culture, six groups were identified: phenols, alcohols, alkenes, monoterpenes, aldehydes and alkanes, being phenols the predominant group (2,4-bis (1,1-dimethyl) phenol 40–88%). P. ochrochloron water culture and M9 culture, reported signals of toxicity: the first one as genotoxic for 0.5 y 1 mg/mL mycotoxin extract and the second one as cytotoxic. M9 media promoted a higher number of compounds in both species and a decrease in phenols predominance in P. ochrochloron but not in P. Purpurogenum. Results showed Penicillium and Debaryomyces as prevalent filamentous fungi and yeast in assessed networks, suggesting that those could be indicators of fungi and yeast presence in drinking water systems.”