How Do Water Well Systems Begin?
Safe, adequate water well systems begin with a good well. True, you can improve water chemistry with many different types of treatment and easily disinfect the water when there are contamination concerns. And it may even possible to boost the output of a low producing well.
But when designing water well systems, it’s really true that “an ounce of prevention is worth a pound of cure.”
The very best way to prevent future water system problems is to base installations on sanitary wells having plenty of capacity and taking the time to plan out the many aspects of an excellent water well system.
There are two possible sources for private water systems:
1) Surface water, found on the surface of the earth in the form of ponds, lakes, streams and rivers etc.
2) Ground water or underground water, found in saturated strata at various steps below the surface of the earth. Of all the fresh water in the world, 3% is in all of the lakes, rivers and streams, while 97% is underground.
How the water cycle operates
Both sources receive their water supply is rain or snow. As it falls to the earth, some of this water collects to form lakes, streams, etc. Some of that operates to return directly to the atmosphere; some is used by growing plants and trees. The rest seeps downward through the earth until it accumulates in porous material at some subsurface level and becomes ground water.
The groundwater isn’t static. It is constantly moving slowly through subsurface strata. Some of it reappears as surface water at some low one point – perhaps a swamp, the bed of the stream, the edge of a lake or maybe a spring.
Surface water is continuously evaporating into the air. It is this action that produces the clouds from which rain and snow fall. As a result water is constantly changing from moisture in the air to rainfall, to surface water, to groundwater, back to surface water, and ultimately back to atmospheric moisture.
This continuous process is known as the hydrologic cycle or water cycle.
Surface water can pose problems for many water wells
Surface water sources require consideration of additional factors, not usually associated with groundwater. The risk of contamination is great. Surface water should be used only when groundwater sources are not available; otherwise only for irrigation, crop watering and the like-not for human or animal consumption if possibly avoidable. Surface water is typically more acidic with a lower pH than ground water. A private household water well system is generally better off when it relies on a stable groundwater source. This water is found in underground strata layers no one as water-bearing formations.
The surface layer in most areas is topsoil. Water passes through it easily. Next, there may be a layer of clay or hardpan. Either material is so tightly packed that resists water flow. Beneath this stratum, or in place of that, there may be more porous or permeable material. Finally comes the water bearing formation, often called the groundwater reservoir.
Water-bearing formations and the water table
There are two basic types of water bearing formations. One is sand, or a mixture of sand and gravel. The other is solid rock, interlaced with crevices or fissures. In the case of a sand-and-gravel formation, the space between individual particles is filled with water. In a rock formation, the water is found in the fissures are cracks.
The water table is a more-or-less continuous surface, below which the formation is saturated with water. Depending on the area, water table depth can vary from a few feet to hundreds of feet. It tends to follow the contours of the land, sloping downward from hilly areas to low points. Obviously, a water well must be deep enough to penetrate below the water table. I’ll explain in future posts that it is usually best to go a good distance below the actual water table.
Water table and artesian wells
In some places, more than one water bearing formation is found under the surface. There might, for example, be a gravel-and-sand formation directly above a rock formation. When the well is drilled down only to the first such formation, where the water table is exposed to atmospheric pressure it is known as a water table well.
Sometimes, a well will be drilled to a lower formation where the water is under pressure because it is confined by and impermeable overlaying layer and at higher elevation this is known as an artesian well in some cases the pressure is great enough in such formations to force the water up to the surface when tapped by a well.
My next post I will discuss the basic types of wells, the cost, problem and trouble shooting water well systems.