Today, we drink water droplets that have been many places before we swallow.
We are not drinking virgin-pure water, unless we manage to capture a fragment of a just-arrived comet that landed in our drinking cup and somehow survived the impact. When the earth formed 4.5 billion years ago, the lighter elements were located further away from the sun, but many comets and asteroids collided with the earth and brought hydrogen and oxygen. In addition, volcanic eruptions contributed intermittent outgassings of water vapor from the earth's interior. Oceans may have been present on earth before the moon was formed, within the first 100 million years of earth's existence.1
For over 4 billion years, the original water in the atmosphere has fallen back to the surface as raindrops, drained to the oceans, evaporated again into the sky, and repeated the hydrologic cycle over and over and over and over again. Some water can be trapped in bedrock, interrupting the cycle. Perhaps the oldest water identified on earth comes from Precambrian rock in a zinc/copper mine in Ontario, Canada. It is a remnant of an ocean that covered Ontario over a billion years ago, and is exposed now only because miners have dug 1.5 miles deep into the ancient bedrock.2
In your cup of water could be an H2O molecule that once eroded the ancient Appalachian Mountains over 200 million years ago, or was slurped up from a mud puddle by a dinosaur wandering through the Culpeper Basin 100 million years ago, or was briefly incorporated in Pennsylvania glaciers that melted away 18,000 years ago.
Once life evolved on earth, some of those water droplets have been taken up by plant roots and then evaporated from leaves. Through "transpiration," water is released as vapor from pores in the leaves (stomata) back into the air. Other water molecules that may be swirling in your cup of coffee may have been swallowed by animals and excreted back into the environment. Since humans developed urban centers in Virginia, especially in the last 200 years, some of those water droplets have been cycled through human bodies, flushed into sewers and septic tanks, and re-entered the groundwater or streams to be recycled again.
So why aren't the water droplets that we drink today contaminated from all the past experiences? After all, the H2O molecules in our glass of drinking water have traveled through the air, ground, streams, and oceans over the billions of years since the earth formed. The water has absorbed various particles in the journey - and odds are excellent that the same H2O molecules in every cup of water that we drink have previously traveled through the intestines of fish, deer, ducks, and maybe even a few humans.
Unless you live at the headwaters of a stream on a watershed divide, you live downstream. Odds are good that something, and someone, absorbed and then excreted the water that you are drinking - and did so within the last two weeks. Between animals in the woods and people in various forms of communities, our H2O molecules go from mouth to toilet to mouth to toilet to mouth, getting recycled over and over.
|If you live in Blacksburg, then the water you drink from the New River has been used in North Carolina and in Virginia communities upstream. If you're in Virginia Beach, drinking water out of the Roanoke River, your water could have been processed through various types of intestines in Salem, Roanoke, Altavista, Brookneal, Martinsville, Danville, South Boston, Hailfax...
During a trip from mountain to ocean, water droplets in streams can get clean naturally naturally - after traveling some distance. Inorganic contaminants (dirt particles, in particular) settle out when a stream slows down in eddies behind rocks. Settling also occurs when the gradient of a stream decreases and water travels slowly, when it enters a lake or reaches the relatively-flat Coastal Plain.
When water droplets are exposed to ultraviolet rays of the sun, or high levels of oxygen after falling over a rock, the DNA of bacteria and viruses is degraded and most biological contaminants are removed during the trip. Plants consume nutrients, and even add oxygen back into the water. H2O molecules absorbed by a plant root will be transported to the leaves and evaporated back into the atmosphere. "Transpiration" shifts H2O molecules from liquid to vapor form, and sterilizes the water in the process... though transpiration removes water from streams, and releases it as water vapor in the atmosphere.
Water pollution is a modern phenomenon in Virginia. Virginia has areas of heavy metal concentration, but contamination of surface drinking water sources in Virginia by ore deposits is uncommon. Near Virginia's richest mineral deposit, the uranium ore body in Pittsylvania County, the water quality of nearby wells is drinkable.
Native American population levels were low, and water contamination by their human wastes were not a major health issue (except perhaps right at a summer village site). Today, however, humans are concentrated in such density that natural processes can not clean our wastewater before the next community downstream plans to use it for drinking water. In addition, urbanizing counties in Northern Virginia and Tidewater are exacerbating "natural" pollution, by removing massive amounts of natural habitat.
New River, downstream from Eggleston
(on the way to being used in West Virginia
and all the way to New Orleans...)
Prior to the arrival of European colonists, wildlife (deer, geese, mice, frogs, fish, etc.) in natural areas would rarely be concentrated enough to create sufficient waste to affect water quality. Predators ensured the animals stayed separated from each other, or moved on. As water ran down natural streams, exposure to sunlight/oxygen soon killed most harmful bacteria and viruses excreted by wildlife. However, today many once-natural areas have been developed as farms and subdivisions.
This transformation of habitat has crowded wildlife unnaturally into narrow strips of vegetation remaining along stream banks. In some cases, geese and deer populations have skyrocketed as subdivisions and office parks have provided new habitat. When concentrated unnaturally, wildlife waste can become a high percentage of the E. coli bacterial contamination found in some stream segments. Some analyses of Total Maximum Daily Loads (TMDL's) of pollution that Virginia streams can absorb have identified places where bacteria coming from wildlife (especially geese) reduce the water quality below acceptable levels, and cause a stream segment to be classified as "impaired" under the Clean Water Act.
It is no longer safe to drink untreated water from any surface source in Virginia. The days when water could be piped directly from a river or a spring to houses, without concern about quality, are gone. Some individual houses still trust their spring or creek, but water systems that serve communities - even trailer parks in rural areas of the state - must treat the water so it meets minimum Federal Safe Drinking Water Act standards.
Many Virginians do not drink treated water. About 500,000 households (37% of the total in Virginia) are serviced by private wells.3 Most private well owners are residents who live away from urbanized areas serviced by a public water system. Residents who drill individual wells to supply water for individual homes rarely include any system to purify water with chlorine, or flouridate the groundwater to protect teeth. Water from individual wells may go through a water softener to remove iron, or to remove calcium and replace it with sodium (creating "soft" water). Replacing calcium ions with sodium ions - provided by the salt that residents put into the water conditioner - helps soap lather, and minimizes the buildup of calcium scale that can clog pipes.
Under the 1974 Safe Water Drinking Act, the Environmental Protection Agency is the Federal agency with responsibility for protecting public water systems. By EPA's definition, public water systems "provide water for human consumption through pipes or other constructed conveyances to at least 15 service connections or serves an average of at least 25 people for at least 60 days a year."
In Virginia, EPA does not approve new waterworks operators or oversee public water systems directly. Instead, the Virginia Department of Health has primary responsibility for compliance with the Safe Water Drinking Act requirements. The state agency maintains a database of over 2,500 public water systems, including 50 alone in Fairfax County (such as the "Transient Non-Community Water Systems" well that provides groundwater to 1,300 visitors at Great Falls Park, and similar wells for drinking water at Gunston Hall and Mason Neck State Park).4
Drinking water treatment plants process raw water taken from wells, rivers, or reservoirs, then process that water in a purification plant. After treatment, the plant will pump water clean enough for humans to drink through a network of pipes to customers.
The quality of the raw water affects the processing required to meet the Safe Drinking Water Act standards, and stay below the Maximum Contaminant Levels (MCL's) established by EPA. When a community's drinking water system uses clean water from the headwaters of a stream, the cost to treat that water and meet state/Federal requirements are lower. "Source water protection" efforts are designed to keep pollution out of water supplies, so the treatment of the water can be minimized. Roanoke has, at times, blocked recreational use of the Carvin Cove reservoir watershed in order to prevent pollution from eroding soil or boat motors. New York City has established the classic example of source water protection, buying property in the Adirondack Mountains to maintain a relatively-pure water supply. By blocking pollution from getting into the water in the first place, New York has avoided the cost of constructing expensive water treatment plants.
When a community's drinking water system uses clean water from the headwaters of a stream, the cost to treat that water and meet requirements are lower. Richmond is downstream of Lynchburg and other communities on the James River. The raw material that will end up in Richmond's drinking water system will require more treatment, compared to the treatment required to process raw water for a community located near the headwaters of the James River (such as Monterey, in Highland County).
Virginia counties who meet the requirements of the state's Chesapeake Bay regulations typically focus on protecting the large, perennial streams that have water flowing in them all year. Developers may be allowed to destroy smaller, intermittent streams, placing them in pipes and filling the stream channel with sediment or pavement. However, the pollution that gets into small streams will inevitably wash down the channel, ending up at the intake of any drinking water plant downstream.
EPA analyzed the Source Protection Areas, the area upstream from a drinking water source or intake that contributes surface water flow to the drinking water intake during a 24-hour period. The agency determined that 58% of the total miles of streams in the US that provide water for public drinking water systems are "intermittent, ephemeral, or headwater streams."5 (Intermittent streams are streams containing water for only part of the year. Ephemeral streams flow only in response to precipitation events.)
In Fairfax and Loudoun counties, the percentage was equivalent - 56%. In Prince William, the percentage was 77%. Evidently EPA lumped the residents in the cities of Manassas/Manassas Park with the county of Prince William, and Lake Manassas relies upon even more intermittent, ephemeral, or headwater streams than the Ocoquan Reservoir.
Even a small community can severely pollute a small river, creating a headache for the drinking water plants downstream. Bassett is a factory town that was "encouraged" by the state to clean up the wastewater dumped into the Smith River. Henry County created a Public Service Authority in part to finance the cleanup. The communities downstream of Bassett are the beneficiaries of the pollution control - as are the fish, wildlife, and recreationists who use that stretch of the Smith River.
Martinsville gets its drinking water from the headwaters of Jones Creek, while Henry County draws its water from Smith River three miles below Philpott Lake. Both avoid extracting water from below Bassett. Philpott Lake serves as a giant settling basin, so it too enhances water quality downstream of the dam. (The Smith River below Philpott Lake is a top fishing destination for brown trout.)
Typically, raw water is purified into drinking water in several steps. Early in the process, settling basins are used to stop the flow of the raw water, allowing sediments to settle out. Alum is added the cause the many tiny particles suspended in the water to "flocculate," bunching together until the clustered particles are so heavy they drop to the bottom of the settling tank. The water is then exposed to chlorine or high levels of ultraviolet light radiation to sterilize the water. Some communities (such as the City of Chesapeake) use reverse osmosis systems to purify water.
Drinking water plants pump their final product from the plant to the customers. Drinking water distribution systems include water towers, in part to store water for peak demands but also in large part to maintain pressure in the system. After pumping water up into the tanks, gravity will push the drinking water through the pipes to customers - even after hurricanes, when electricity might be out.
Since all of Virginia experiences freezing temperatures at least occasionally, the pipes are underground - unlike the electricity distribution network, where the maze of overhead wires exposes clearly the geographic pattern of a few centralized sources providing electricity to many individual customers.
There is an economy of scale in creating safe-to-drink water, comparable to the economics of producing electricity. Drinking water treatment plants mimic natural processes to strip contamination from raw water. Making water safe to drink involves using settling tanks, chemicals and ultraviolet light, to accelerate the decontamination that occurs naturally over longer distance/time.
The treatment process in drinking water treatment plants is very similar to not only natural processes, but also to how sewage is treated in wastewater treatment plants. Solids are removed, chemicals are added/UV light used to kill protozoa and disrupt the DNA of bacteria/viruses, and the final product is inspected before being released. Water that leaves a public drinking water plant is pure enough for human consumption. Once it enters the pipes, there is a risk of contamination. In rare cases, cracks in the drinking water pipes (created by settling, or tree roots) may allow contaminated groundwater to get into the drinking water distribution system. Most often, however, contamination is introduced at the very end of the distribution process, especially in residences with lead or copper pipes.
When the drinking water gets to our houses, we may percolate it through coffee grounds, mix it with frozen lemonade, or drink the water straight. However, we also use drinking water to cook pasta for 8 minutes at a roiling boil. We use drinking water to take showers, clean laundry, flush away waste in toilets, and water lawns. In many Virginia communities, we use drinking water to supply hydrants for fighting fires. As little as 5-10% of the "drinking" water produced by the Fairfax County drinking water plant on Route 123 near Lorton will actually be swallowed by humans.
Different utilities charge different fees for the water that they sell - and some water companies are for-profit businesses. A comparison produced by the Fairfax Water utility in 2010 showed that Fairfax Water charged the lowest rate of any utility in Northern Virginia.6
In 2010, the Virginia-American Water Company charged its customers in Prince William County 160% higher rates than Fairfax Water charged its customers in southern Fairfax County - though the two utilities were selling exactly the same water. Fairfax Water produced and shipped processed drinking water across the Occoquan River to the Virginia-American Water Company, which then distributed that water in Dale City. Fairfax Water sold the same water, primarily from the Frederick P. Griffith Water Treatment Plant, in southern Fairfax County.
Why the difference in rates? The Virginia-American Water Company is a for-profit, investor-owned utility - a private company - while Fairfax Water is a non-profit public utility. The State Corporation Commission must approve rates set by private utilities, so the private company does not have total freedom in setting its fees to customers. It justifies the higher rates in part by claiming its costs for maintaining infrastructure and billing systems are different from the costs in Fairfax County.