As input to the ongoing discussions about how to meet and overcome the spreading risks of Ebola, here are some summary thoughts about the water-related components of U.S. efforts. Specifics about the operations and effectiveness of water treatment or supply technologies, or the medical and health implications of their use must be verified by the designers/makers of the technology along with medical experts from the US Centers for Disease Control (CDC), World Health Organization (WHO), West African health and water officials, and related institutions. 1. Water Supply Needs and Usage
Any medical facility, hospital, field station, isolation unit must have a supply of fresh water that is adequate in flow volume and quality. This requirement, and the need to develop such a reliable supply in advance of facility construction or placement, is as or more vital than the need for reliable electricity, although as noted below, these two resource needs are also related and connected. Volume of Water Needed
Few studies have assessed average water use by hospitals; fewer have done this assessment for emergency field isolation units or rural medical units. Larger hospitals are reported to use between 40 to 350 gallons per patient per day (150 to 1300 liters per person per day), but only about 60% of this is used for medical procedures and sanitary purposes. Another source identifies typical urban hospital hot water demand at around 35 gallons per person per day (160 liters per person per day).
While these data suggest that emergency minimum water supply volumes on the order of 150 to 200 liters per person per day might be sufficient, it should be a top priority to inquire of current medical facilities in Liberia, Guinea, and other affected areas of West Africa for specific data and insights on their current level of water use as well as the end uses of that water (washing, sanitation, sterilization of equipment, cooking, etc.). Water Sources
Water sources can include rainwater, surface water from rivers, surface water from lakes and ponds, groundwater/aquifers, remote delivery via tanker, pipeline, or municipal system. The availability of these options is highly locally specific, and no general recommendation can be made without knowledge of the site to be chosen for a treatment facility. It is thus vital that early and fast assessments be conducted of available water sources (including both quantity and quality). Given the high variability of the hydrology and climate in West Africa, a reliable source of safe, clean groundwater may prove to be the best option, but will require a geophysical assessment and an experienced water well drilling team, together with sufficient engineering expertise to install the necessary pumping and treatment infrastructure. Quality
It is essential that the quality of at least part of the water supply be potable, as defined by World Health Organization, European Commission, or U.S. Environmental Protection Administration standards. (Any one of these standards would be sufficient.) Water protected to a “potable” standard will greatly reduce the risk of additional water-related diseases, which would vastly worsen the health outcome of both working staff and patients. This will require either a guaranteed source of water that is safe, or an on-site treatment system that can purify water of any available source to a specified, desired quality. An on-site system is preferable because of the greater certainty (compared to depending on natural purity of a potentially unreliable or variable source), but it has higher operational complexity and costs.
A key point: water use in an emergency field hospital can be split into both potable/high quality and non-potable needs. If non-potable water is available, and there are substantial water-use requirements that do NOT require potable water, the system required to produce potable water can be smaller, less energy intensive, and less costly. In such a “dual-system” case, however, care must be taken to ensure that potable and non-potable needs and supplies are kept separate and isolated to prevent cross-contamination risks. Energy-Water Nexus Issues
Both reliable energy and water are vitally important resources for any emergency medical facility. As part of the need to supply water, however, there are also significant energy needs for:
- Water-supply delivery (via pumping of groundwater, pipeline operation, or tanker delivery)
- Water treatment is often energy-intensive, depending on the methods used (boiling, membrane operation, ozone or ultraviolet disinfection, etc.)
The Table below shows the energy requirements for various water-treatment technologies. In planning the total energy system needs for any facility, these water-related energy demands must be taken into account, along with the backup water storage needed to provide treated water in the event of energy outages.