When our house was built 18 yrs ago the cap on our water well casing projected about 8 inches above the ground. We haven't changed the grade level, but the cap has sunk into the earth so that it is now just about level with the surface. I am concerned that during a rain, surface water might seep between the cap and casing and contaminate the well water.

Anyone know if my concerns are legitimate? And, if so, what can be done to correct the situation? Is there an extension that can be sealed to the top of the old well casing to extend it upwards again. Finally, I remember reading that this behavior is common in shale/clay type conditions (which we have). Can anyone confirm that recollection, or provide an alternative explanation.

The well is several hundred feet deep, and I'm hoping that we don't need to have the casing removed and reset.

Thanks in advance for your help.