A rapid infiltration land wastewater application site, composed of unconsolidated silty sand and gravel, which has been in continuous operation for over 30 years was examined for the accumulation and/or migration of a tracer virus (coliphage f2), indigenous enteroviruses, and enteric indicator bacteria in the soils and underlying groundwater. Tracer f2 penetrated into groundwater together with the front of percolating primary effluent and was not observed to concentrate on the upper soil layers. The tracer virus concentration in a 60-foot (about 18.3-m)-deep observation well directly beneath the wastewater application area began to increase within 48 h after application to the soil. The tracer level in this well stabilized after 72 h at a level of approximately 47% of the average applied concentration. Indigenous enteroviruses and tracer f2 were sporadically detected in the groundwater at horizontal distances of 600 feet (about 183 m) from the application zone. Laboratory soil adsorption studies confirmed the poor virus adsorption observed at the site. This was especially true on surface soils when contained in wastewater. Enteric indicator bacteria were readily concentrated on the soil surface by filtration on the soil surface mat. However, during tracer f2 virus tests, comparison studies with fecal Streptococcus revealed that bacteria capable of penetrating the surface were able to migrate into the groundwater. They were detected at the same locations as tracer and enteric viruses. Land application has been used as a wastewater disposal method for many years. Wastewater can be applied by spray irrigation, overland flow, or rapid infiltration. Treatment effectiveness is a function of the physical, chemical, and biological properties of the soil as well as wastewater application practices. There are several major advantages to wastewater disposal by land application, including relatively low system capital and operating costs, unsophisticated facility requirements, the value of the nutrients imparted to the land, and recharge of groundwater by infiltrationpercolation. Unfortunately, there are several potential problem areas which need more definition. For example, the actual effectiveness of land application of wastewater in removing enteric microorganisms is not fully understood. A number of studies have attempted to evaluate the enteric microbial removal potential of soils. McGauhey and Krone (9) summarized existing information and concluded that coliforms and other bacteria move only a few feet in an unsaturated zone and several hundred feet in a saturated zone. These investigators indicated that bacteria behave like other particulates in soil and are removed by straining, sedimentation, entrapment, and adsorption, and are influenced adversely by antagonistic environmental factors. They concluded that soil systems are quite efficient in removing bacteria and hypothesized that viruses can be removed with equal effectiveness, principally by adsorption. Driver and co-workers (4) reviewed previous studies and supp...

Caliciviruses are disseminated by the fecal-oral route and are found in contaminated surface and ground waters. The US Environmental Protection Agency (EPA) is interested in preventing calicivirus contamination in treated waters used for consumption, and these viruses are on the EPA's "contaminant candidate list" for regulatory consideration in drinking waters. These viruses also present a health threat for recreation and shellfish-growing waters. However, before EPA can make regulatory decisions regarding caliciviruses, significant information and technology needs must be established, including analytical methods for sampling, identifying, and quantifying the viruses; applicability of surrogates to determine their presence; efficacy of water and wastewater treatment or disinfection; waterborne occurrence levels and distribution; dose response; and the viruses' effect(s) on health. Future drinking-water regulations may need to ensure that treatments are adequate to remove caliciviruses from source waters. For recreation and shellfish-growing waters, surrogate indicators and health criteria may need to be based upon establishing risks of exposure to caliciviruses.

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A number of approaches offer promise for addressing the limitations of current antibody‐based detection methods. This report was prepared by the Working Group on Waterborne Cryptosporidiosis (Technical Task Force E, Developmental Status of Environmental Sampling, Water Testing, and Surrogate Indicators). Methods for detecting Cryptosporidium oocysts in water have centered around microscopic examination of fluorescent antibody‐stained concentrates from large‐volume water samples. The limitations of these antibody‐based methods include the need for experienced analysts, lengthy analytical time, expense, lack of specificity, erratic efficiency, low precision, and difficulty in determining viability. A number of methods, assays, and procedures that have the potential for ameliorating some of these limitations are currently being evaluated. How successful such processes will be remains to be demonstrated by the scientific community.

The U.S. Army is evaluating recycle of field shower water as a conservation practice in arid regions and is seeking to define appropriate technologies and health criteria. Shower wastewaters at a military installation have been characterized in terms of physical, chemical and microbiological parameters. Two treatment technologies have been investigated. Microfiltration cartridges with a nominal pore size of 0.2 µm achieved consistent removals of 75±15% of total organic carbon (TOC) and better than 99% of turbidity from synthetic shower water containing 50 to 100 mg/L of TOC as soap. An alternative treatment technology utilized powdered activated carbon and coagulation/flocculation/sedimentation followed by diatomaceous earth filtration. A TOC reduction of 70±15% was achieved in three separate studies, although at a cost of 1 g/L or more of powdered activated carbon. Revised quality criteria for recycled shower water have been developed with guidance from the National Research Council. Parameters which can practically be measured in the field are primarily associated with microbiological safety. Therefore, the safety of recycled shower water with respect to chemical contamination must depend on design considerations.