While there is no specific maximum contaminant level (MCL) for sand or particulates in drinking water, sediment or sand can carry chemical or microbial contaminants through the processes of absorption and adsorption. Many of these chemical and microbial contaminants can be harmful to public health. Additionally, particles in water, such as sand and sediment, can shield pathogenic organisms (pathogens) from exposure to disinfectants (commonly, chlorine). Disinfection is an important part of the water treatment process. The EPA has established specific MCLs for many chemicals and pathogens found in drinking water sources. Some MCLs depend on how the water source is treated. It is important to note however, that the Safe Drinking Water Act (SDWA) does establish a limit on the “cloudiness” of water leaving a water treatment facility, which is called turbidity. The turbidity itself is not the health concern, but rather it is used as a measure of the microbial safety of the water (pathogens associated with particles which can shield the pathogens from disinfectant). There are no stipulations on the particle size, however the way turbidity is measured in most meters, the higher the average particle size and concentration, the higher the turbidity reading will be.
The current regulation for turbidity (which is a primary drinking water standard) depends on the water treatment technique. For water systems that use conventional or direct filtration, at no time can turbidity (cloudiness of water) exceed 1.0 nephelometric turbidity unit (NTU), and samples for turbidity must be less than or equal to 0.3 NTU in at least 95 percent of the samples in any month. Systems that use filtration other than conventional or direct filtration must follow state-established limits, which must include turbidity at no time exceeding 5.0 NTU.
With regard to optimal turbidity measurements to best protect public health however, EPA recommends an “optimized” goal of 0.1 NTU for 95% of the individual filter samples in any month and never exceeding 0.3 NTU. Research has shown a substantial reduction in microbial pathogens by reducing turbidity from the current regulation of 0.3 NTU to 0.1 NTU.
A cursory literature search does not yield any specific information or data on health effects of consuming sand or sediment, aside from the effects caused by chemical or pathogenic contaminants that could be associated with the sand or sediment particles.