Water supply and Sanitation

Aquifer is a very broad term that has different meaning depending on the application. It is basically any saturated layer that conducts water. Depending on the site geology, it is typically associated with contiguous layer of saturated sand. However, it could be continuous factures in rock, or a more pervious layer of clay within less pervious clay. In most situations, if you know the approximate depth to groundwater, a PCPT is one of the easiest methods to evaluate the geology and the local conductivity, if dissipation is performed. Alternately, drill a hole, sample in intervals , find a more pervious geologic formation, install a test weel and do draw down testing.

One way is to use a 3-well method. Find or locate any 3 existing wells that are already in operation within or close to the area under consideration. It is important that these 3 wells will form a triangle arrangement. Do some sort of survey using a suitable instrument (or even use of GPS/GIS if available) to determine distances and elevations between and for each well. Consider to establish an elevation of each and record depth of water table. Depending on contours/topography and/or geology of the area within the 3 wells you can establish an imaginary plane for the water table to approximate the depth of the water table for a well.

Another way,...use trial and error. It may work simpler/easier or even harder than above depending on the geology of the area.

Get help from India's Panee BABAs(Water Diviners).

Only sensors are :A stick + some Mantra-s

They use those guys (local equivalent) here in Mexico. 100% right so far (he is 55).

Short of having geophysical testing done at the site (to define the depth of bedrock), you have a few options. First, you should ask any drillers in the area what they have experienced as the depth to the aquifers; also if there are hand dug wells nearby you should check the depth to water in them.The topography of the area gives some general insight into the likely depth to groundwater, since the aquifer(s) will generally follow (somewhat) the topography of the area. As a final option, you might consider drilling a pilot hole into the soil while looking at the types of clays, coarse sands and gravels occurring and the levels below surface at which they occur. Typically, water flowing through an aquifer flows to a stream/river/pond or lake and enters the water collection from below grade. For that reason, if you are elevated above such a stream you can get an approximate fix on the distance to the aquifer.

Aquifers act as both storage and conduits for water. I would suggest googling "Hydrology Cycle" or "Water Cycle". The water in an aquifer decreases primarily because it is flowing into streams, etc. The water n the aquifer is generally replenished by the rains, so the level will rise and fall slowly over time.