Wells abstracting groundwater are often susceptible to screen slot (chemical) clogging and well bore (mechanical) clogging. Well clogging can cause a decrease of a well—s specific capacity over time and may threaten its reliability. Both types of clogging can be easily diagnosed during operation with the help of entrance resistance—the difference in head between the abstraction well and the observation well in its gravel pack. An increase in entrance resistance over time indicates screen slot clogging. The increasing resistance is caused by accumulation of chemical precipitates in the screen slots and adjacent gravel pack. Well bore clogging, however, does not show an increase in entrance resistance. Both types of clogging can be easily prevented, or at least mitigated, by two opposing methods of well operation: continuous abstraction for wells susceptible to screen slot clogging, and discontinuous abstraction (alternating operation with idle periods) for wells susceptible to well bore clogging.

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Wellfield "Tull en 't Waal" (water utility Vitens Midden Nederland) suffers extensively from wellbore (or mechanical) clogging. To prevent this type of clogging, wells have been operated intermittently since August 2005 using a carrousel well operation schedule. Since the introduction of this schedule, wellbore clogging has become minimal.