Facts About Groundwater

Learn some basic facts about groundwater, and a DIY Spring Box project.

Facts about groundwater

Groundwater, the source of drinking water for about half of North America's population, loses many of its contaminants on the the way down to the underground aquifers.

Photo by Fotolia/Tamas Zsebok

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With solid and easy-to-understand advice, Country & Cottage Water Systems (Cottage Life Books, 2010) is perfect for anyone who needs help comprehending the mysteries of rural water systems. From wells to outhouses, Max Burns, has the DIY projects and illustrations needed to bring the clean water in and send the waste out. With this excerpt from “Water Sources: Assessing your options,” learn some basic facts about groundwater and building a DIY spring box.

You can purchase this book from the GRIT store: Country & Cottage Water Systems

Facts About Groundwater That You Should Know

While it's true that systems drawing from groundwater sources rather than surface water sources are more reliable and don't require the same level of seasonal cold-weather preparations, the principal motivator for choosing groundwater as a source for drinking water remains concern over water quality. Simply put, groundwater is less susceptible to contamination.

Groundwater, hidden away in underground aquifers, is the source of drinking water for about half the population of North America. Aquifers can be pockets of porous earth that hold water much as a sponge does, or fractures and under-ground caverns in rock. Aquifers can be isolated tankards or an interconnected series of reservoirs that can extend for miles. Some aquifers lie just a few feet below the surface, with their water levels being topped up every time it rains. Rainwater being naturally soft and acidic, and therefore slightly corrosive, absorbs soluble minerals from the rock and becomes harder as it percolates through earth. Simultaneously, microorganisms and many harmful chemicals accumulated from the atmosphere and initial contact with the earth's surface are gradually left behind as the water continues to filter downward. This tendency for water to swap contaminants with earth usually increases in proportion to the depths it must travel before joining up with a suitable aquifer, so deeper is considered better from a quality standpoint. And the deeper the aquifer, the more likely its contents will be unaffected by rainwater and whatever else is happening on the surface. In fact, it's quite possible for acquifers to lie undisturbed for millennia. Either way, it's this natural cleansing process and relative isolation that makes groundwater a safer and more consistent source of potable water than surface water. That said, once polluted, groundwater will likely remain that way for a very long time. How does it get polluted? Usually via some connection to the surface, such as a spring or a well.

When the weight of the earth above an aquifer exerts a force on the water within it that is greater than atmospheric pressure, that water will rise whenever a connection is made, whether that connection is naturally occurring or one constructed by us. Normally, this simply brings the height of the water closer to the surface but if the pressure is great enough, water will pour out that connection's exit as if someone left the tap running. We call this an artesian spring or flowing (or artesian) well.

Spring Water

Spring water has the reputation of being the cat's meow, but in reality, it can be closer to some of the other things a cat emits. While it's true that water loses many of its worldly contaminants en route to finding an aquifer, if the return trip to the surface is unprotected there's little to stop contaminants from rejoining the flow. A well has a lining or casing to help protect it; a spring has nothing. Therefore spring water almost invariably must be treated to ensure it's safe for drinking.

There are two types of springs: gravity-fed springs, which are most often found flowing from a hillside; and artesian springs, which are fed by an aquifer under pressure. Artesian springs are less likely to stop running during dry spells and are less prone to pollution (but not immune to it).

DIY Spring Box

Contamination at the surface - from animals stopping by to take a drink and maybe drop off a contribution - can be curtailed by building a spring box. This "box" is essentially a cistern or dug well sitting at the mouth of the spring, complete with lid. But rather than being fed by surface water, it's fed by the spring. Therefore, it shares many of the same construction criteria, though you'll want to check with local  authorities regarding any additional restrictions in your jurisdiction. Well tiles, 3' (1 m) in diameter, make for an economical spring box, one reason I chose them to box the artesian spring on my own property. Be forewarned, these tiles are extremely heavy - even Waldo, my aged backhoe, had trouble lifting them into place. Those without backhoes should have a good cache of friends to call upon come time to manoeuvre the tiles into place. (The main advantage to the backhoe, of course, is that it doesn't come with accompanying advice.)

In common with the dug well, a spring box will usually have an intake line running through the wall of the box to a pump, but with or without this luxury, it will need a screened overflow - a pipe terminating away from the area surrounding the spring - to reduce soil erosion near the box. Drainage ditches dug uphill of the spring to divert surface runoff away from the area will also reduce the potential for pollution.

Read more: Begin your education in rural water solutions with DIY Water Storage.

Reprinted with permission from Country & Cottage Water Systems by Max Burns and published by Cottage Life Books, 2010. Buy this book from our store: Country & Cottage Water Systems.