In fact, it depends on the ...

In fact, it depends on the thickness strata of groundwater containing formations.

The planning and calculation of a water supply well, are the strata of water influx the basis of all calculations. If these interchangeable deposits occur to an increased degree (eg, all 0.20m medium sand "with water", then 0.50m clay (without water) etc.) and are not powerful enough or even less than 1.0m thick, and not more than 5m thickness throughout the whole vertical profile, then you go, even with a drilled bore, with the drill diameter rather in the width, than in the depth !! 

In some areas, bore diameters of 1000mm and larger are achieved, even in municipal water supply, worldwide. If this still does not prove sufficient for the calculated required water production, then it makes sense to create a shaft- or a dug-well. There are some cities where e.g. then also horizontal filter wells are built. These are manhole wells with a width of more than 2.5m and then horzotal well filter tubes are drilled into the water horizons ...

 

Another example is the typical dugwell on islands, closed to the beach. There, you won't succes if you don't respect the strata of sweet water...drilled wells won't succed, you have to look for width.

I hope, its clear enough :-)

For any kind of questions or further help, do not hesitate to contact me.   

 

So far good luck,

 

Ulf