Before any new water source protection is developed or maintenance is planned on an existing source, it is important to conduct a sanitary survey. A sanitary survey is an evaluation of the physical environment to identify possible health hazards and sources of environmental contamination. It will reveal the potential risks to the health of people that may arise from the proposed water source. The risks may be negligible or they may need to be controlled with specific correction activities. This sanitary survey will be part of the baseline information for the water source development and should include the nature of the water-bearing layer, the hydraulic gradient (i.e. the variations in underground water pressure that affect the natural flow of water), topography, vegetation, potential sources of contamination, and the adequacy of the yield particularly for dry seasons.