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Six-month Safe Storage Evaluation



Water for ME

Water for ME worked with community members to build a well in Gros Morne, Haiti in 2015

Water for ME is a non-profit organization established to aid in the research, design, implementation and funding of clean water systems, particularly in Colombia, Haiti and Honduras. The organization helps to provide a structure for meeting water needs while creating a collaborative framework for researchers, teachers and students to study and improve water quality.

In association with the University of Maine at Orono and the Newton-San Juan del Sur Sister City Project, Water for ME researchers undertook a six-month safe storage evaluation of the MadiDrop in support of safe water initiatives in the community of San Juan del Sur, Nicaragua. The San Juan del Sur project has championed the effective use of biosand filters in homes in the region, but contamination of water storage buckets continues to be a problem in these communities. The study is part of the broader goal of addressing the United Nations Millennium Development Goals of sustainable access to safe drinking water by developing solutions for safe water storage.

MadiDrop Lab Testing

The MadiDrop six-month laboratory study addressed the contamination issue in storage buckets using a combination of water spiked with E. coli and Kenduskeag Stream water or Stillwater River water, both known to contain varying levels of microbial contamination. Research was conducted under the direction of Dr. Barbara Stewart, an adjunct faculty member of the Chemistry Department of the University of Maine and teacher at Bangor High School, and Catherine Hopper, an instructor in the Department of Molecular and Biomedical Sciences at the University of Maine.

Testing conditions included pre and post levels of E. coli, total coliforms, turbidity, temperature, pH, and conductivity. M-Drops were tested in effluent from four working biosand filters as well as in samples spiked with varying levels of E. coli in DI water and in local river water.


Results from the E. coli spikes and silver ion concentrations showed the M-Drop performed to specifications. Microbiological analysis was performed on both source, biosand pre-filtration and treated water using Standard Methods’ most probable number (MPN) method for the simultaneous detection of total coliforms and E. Coli. Sample processing and analysis were performed in accordance with IDEXX and Colilert procedures.

All M-Drop-treated samples were tested at 1, 7 and 14 days of stagnation. In all cases, ionic silver concentrations were below 100 µg/l.

Across multiple experiments and water conditions, tests for total coliform and E.coli showed total disinfection at 24 hours, demonstrating significant reductions in total coliform and inactivation of E.coli. In general, results for total coliforms and E.coli at 24 hours showed:

Source Water: Too Numerous to Count (TNTC)

M-Drop treated source water: <1 CFU/100ml (non-detectable) M-Drop treated EC spiked: <1 CFU/100ml (non-detectable)

Tests from water storage containers taken at Days 7, 14 and 62 showed zero regrowth of total coliform or E.coli. in any of the water conditions, demonstrating the effectiveness of the M-Drop as a safe storage solution.

Water for ME is preparing to work with implementers in Nicaragua to introduce M-Drops to communities in the region.