Efficacy of locally-available cleaning methods in removing biofilms from taps and surfaces of household water storage containers

Abstract

Biofilms are aggregates of microorganisms attached to surfaces that can (re)contaminate water by releasing microorganisms. We grew E. coli biofilms on household taps and on storage container coupons, and cleaned them with locally-available agents (bleach, boiled water, soapy water, vinegar) and methods (flowing, scrubbing, or soaking taps; soaking and wiping container coupons). After cleaning, we enumerated surface E. coli and imaged biofilms using epifluorescence microscopy. Biofilms were removed from taps when: soaking assembled for five minutes (bleach, boiled water); and, scrubbing and soaking unassembled for five minutes (bleach, boiled water, vinegar). Only soaking methods removed E. coli from container coupons. To remove biofilms, we recommend soaking assembled taps in boiled water for five minutes. No recommendation for cleaning containers emerged as soaking storage containers is impractical. Results are consistent with biofilm research, and highlight the need for technical research to develop realistic cleaning recommendations for water storage containers in households.

Household Disinfection Interventions to Prevent Cholera Transmission: Facilitators, Barriers, Training, and Evidence Needs

“… 32 We recommended using 0.2% and 0.05% chlorine solutions, which are different than the concentrations used during previous work 15 , 22 but are recommended by the CDC 24 and UNICEF 31 and are easy to prepare using a household chlorine solution. 33 After HDK use, in almost all households, there were still some contaminated surfaces. This is consistent with residual contamination observed after household spraying by programs without systematic spraying procedures.…”

Survival and growth of Vibrio cholerae and Escherichia coli in treated groundwater consumed in northern Cameroon

“…Overall, concentration of E. coli increased slightly in all microcosms except in CTW and FWW where it decreased during water storage. Residual chlorine in tap water would have inhibited the growth of E. coli during water storage (LeChevallier 2003;Vital 2010;String et al 2020). According to Mary et al (2001), the survival of allochthonous bacteria such as E. coli in filtered water could be reduced by the presence of "ultramicrocells" of autochthonous bacterial microflora, due to nutrient competition exerted by bacteriolytic enzymes of membrane vesicles produced by native microflora.…”

Drinking water quality and the SDGs

“…The links between water service continuity and quality are well-established yet studies in this collection demonstrate that monitoring hours of service can be difficult 11 and note the risks of considering water quality and quantity in isolation 12 . String et al investigated methods for cleaning household storage containers but did not identify a practical method for removing biofilms 13 illustrating the challenges these households faceand filling a gap in the biofilms literature which has largely focused on piped water systems. Naser et al highlight specific concerns associated with the growing use of rainwater in Bangladesh which go beyond ensuring that it is free from contamination and consider the implications of mineral deficiencies for cardiovascular diseases 14 .…”