Just found from the Internet as reference:
One of two things is happening; either you are observing ordinary water seepage or you are observing "spotting'.
In the case of ordinary water seepage, water from rain lands on the ground and soaks into the ground. The roof gutters may be clogged or may be dumping water very close to the exterior wall of the house. The ground may be sloping toward the house, which traps water and guarantees that it will soak into the soil immediately adjacent to the house.
The earth surrounding the basement walls absorbs all the water like a sponge until it can't hold any more, at which point gravity pulls it through the sponge, out the bottom and into the joint between the basement wall and the basement floor of your house. a trickle of water streams into the crack at this joint and onto the basement floor, but you can't see it, because it is covered by carpet. The water then travels horizontally until it finds the lowest point in the basement floor, and forms a puddle there. The water accumulates at that point until you discover a wet spot in the carpet. You can discover whether this is happening by temporarily lifting the carpet around the edges and seeing if there is a trickle of water coming in.
The other option is called "spotting". In this case, everything is the same except that the water, instead of coming through the joint between the basement wall and the floor, goes under the floor until it finds the path of least resistance somewhere in the middle of the floor, such as a crack or pinhole, and the water is forced up by the pressure of the surrounding wet soil.
In either case, the cure is the same.
1.) clean all the gutters and make sure the water coming from them is discharging at least six feet away from the house.
2.) systematically adjust the incline of the soil around the house so that it is sloping approximately one inch per foot downhill away from the house. The soil must be compacted and have a high clay content. If clay is not available, use a layer of plastic and cover it with mulch.
3.) wait about six months or until you receive several big rains. You should notice a dramatic lessening of the symptoms. You are more than likely to find the problem totally cured.
4.) Do not call basement waterproofing companies or install a sump pump. Such systems are best suited to water appearing in a basement which is not associated with rain events, such as an underground spring. In my opinion, installing sump pumps for a rain-associated water seepage condition is a waste of money.