The Environmental Impact of Data Centers

At the last meeting of the Potomac Watershed Roundtable Julie Bolthouse, Director of Land Use, at the Piedmont Environmental Council gave a presentation titled "The Environmental Impact of Data Centers.” The Piedmont Environmental Council (PEC) has extensively documented the environmental impact from data centers, in Virginia, which hosts the world's largest concentration of data centers in the world. I would like to present a few highlights from her talk.

Data Centers are no longer the office parks of the last century that employed lots of people (remember AOL, now long gone). They are now hyperscale behemoths which employ only a handful of people for landscape, security, and a few operators. According to PEC research, the expansion of the data center industry poses significant risks to energy grids, water resources, air quality, and local ecosystems.

This is especially true in Virginia which has three times the mega watts (MW) and square feet of data centers than anywhere else in the nation. Currently, there are about 70 million square feet of data centers now operating in Virginia; however, there are 285 million square feet of data centers that are approved or in the pipeline.

Along with the massive increase in square footage of data centers, is skyrocketing energy demand. In 2025 data centers used 24 Gigawatts (GW) of electricity in Virginia by 2030 data centers are forecast to use 57 GW in Virginia. A gigawatt (GW) is equivalent to the energy generated by a nuclear reactor or gas plant. Dominion Energy of Virginia has received 70 GW of load request and have 48 GW in contracts for power-21 GW of this is in the final stages of contract.

Due to the demand strain, Dominion Energy is providing incremental load. For example, when Dominion Energy receives a request for 300 MW of power, they start the customer with 25 MW and Dominion Energy vamps them up over time.

This all seems wildly out of control and unplanned be each locality only looks at land use. The locality does not look at the power demand or where the power lines will go. More concerning is that the cost of transmission lines and generation is spread amongst all power customers. The old model allocated costs assuming that residential growth is what was driving the growth in power demand, and large customers like data centers receive discounted rates. Of the transmission projects on Dominion Energy’s books:

• $2.4 billion for transmission lines that will provide power only for data centers
• $3.3 billion for transmission lines that will server data centers and other customers
• $1.8 billion for transmission lines that will serve others

Data centers are also impacting the air quality in our region. Data centers rely on massive diesel backup generators for outages. In Loudoun County alone, permits exist for over 4,000 generators with a combined capacity of 11 gigawatts. In all of Virginia there are 10,000 Tier II permitted diesel generators. In Sterling alone, there are 2,000 older Tier II diesel generators. . A PEC-commissioned study found that on-site power emissions could result in up to $99 million annually in health-related damages due to premature mortality and respiratory diseases. This is mostly from PM 2.5 micrograms/m3.

New power plants proposal are also impacting air quality. PJM is modeling that Virginia is going to triple their power generation and that is going to come primarily from gas turbines with data centers installing on-site gas turbines. DEQ recently changed their rules to allow data centers to essentially use their back up generators as peaker plants to avoid tanking down the grid.

Finally, water. Depending on the cooling system, a single data center can consume 3–5 million gallons of water daily, 60%-80% of this water use is consumptive. Julie warns that this usage stresses local watersheds and the Potomac river, especially during drought conditions which we have been experiencing the past few years. In Loudoun, the reclaimed water from the wastewater treatment plant is maxed out at 697 million gallons/day (90% of this is going to data centers). So the Loudoun County data centers draw an additional 952 million gallons of potable water to cool the data centers. While data centers represent only 1-2% of the water drawn from the Potomac River on average, in summer, data centers are 9-12% of the consumptive use of the Potomac River.

The wastewater from data centers contains high levels of salinity and total dissolved solids, corrosion inhibitors, biocides, chlorine, phosphates and other additives. The wastewater treatment plants can’t effectively remove all these contaminants.

The Key Environmental Impacts 

In summary Julie highlights several critical areas where data centers affect the environment:

• Energy Consumption & Grid Strain: This demand from data centers has led Dominion Energy to delay the retirement of coal plants and expand natural gas infrastructure to maintain reliability, threatening state climate and decarbonization goals.
• Water Usage: Depending on the cooling system, a single data center can consume 3–5 million gallons of water daily. This growing water use stresses local watersheds and the Potomac River, especially during drought conditions.
• Air Quality & Public Health: Data centers rely on massive diesel backup generators for outages. These generators increase the small particulate matter in our air.
• The data center buildout converts thousands of acres of agricultural land and forests into impervious surfaces, leading to increased stormwater runoff and pollution in local waterways.
• Local Community Impacts: Proximity to residential areas brings persistent noise pollution from industrial cooling fans and light pollution from 24/7 facility operations.

Prince William County Prefers Concentrated Development

Based on recent approvals and rezonings it is clear that the Prince William Board of Supervisors and Planning Department prefer concentrated development for Prince William County. They rationalize that they can use building techniques to protect the Occoquan Watershed as a substitute for maintaining open wooded areas. This rationalization is based on the belief that concentrated development paired with advanced technological mitigation can manage environmental impacts better than the "status quo" of rural development. I do not believe that they are right.  

The Board and Planning staff have argued that large-scale development allows for "unprecedented levels of environmental protection" that would not occur if the land remained privately owned and developed at lower densities. This is true, but it has served to protect the Occoquan Watershed for all of Northern Virginia.

Supporters, including Supervisor Kenny Boddye, argue that developers can implement specialized stormwater management systems that filter sediment and pollutants more effectively than the natural runoff from a privately owned 5-acre lot. There is no research for this argument either for or against.

Proponents also suggest that low-density rural development is less protected because the county has limited authority to regulate what chemicals (like fertilizers) private homeowners use or to prevent them from clear-cutting their own property. However, there are no restrictions on what chemicals hundreds of individual homeowners can use either. Small lot communities are notorious for their intense fertilization and management of the appearance of the community.

Though high-density approvals often come with proffered conservation easements that legally preserve a portion of the forest in perpetuity, there may be limited benefit to the watershed. The "edge effect" changes the soil moisture and temperature. This kills off sensitive native plants and allows hardy invasives to take over the ground layer. Within a decade, the small area forest has no "recruitment"—meaning no young native trees are growing to replace the old ones and it dies. The proffers contain no allowance for maintaining the forest.  In the Occoquan Watershed, a 50-acre contiguous forest is exponentially more valuable than five 10-acre "preserved" patches surrounded by pavement. The latter will almost certainly succumb to the "choke" within 15 years.

County staff have noted that while wooded areas help with traditional pollutants, "modern" concerns like increasing salinity (from road salt) are regional issues that require infrastructure-based management strategies rather than just land preservation. However, Extensive research, primarily led by the Occoquan Watershed Monitoring Laboratory (OWML) and published in journals like Nature, confirms a direct link between population growth and rising sodium levels in the Occoquan Reservoir. Average sodium concentrations at the dam have nearly tripled since the 1980s, now frequently exceeding health advisory limits. 

Research shows that for every 100 additional people per km², impervious cover in the watershed increases by 3%. This expansion leads to higher road salt application, with salt spikes occurring even as regional snowfall has decreased by 40% over the last century. In addition, approximately 64% of salt ions in the reservoir originate from the population via reclaimed water. You have more people and you have more salt. Also, research by Bhide et al. (2021) found that roughly 32% of the sodium mass in finished drinking water comes from the treatment plant itself due to chemicals (like sodium hydroxide) added to buffer pH and prevent pipe corrosion. 

The Planning Department's approach often involves "condensing development down" to specific areas, which they believe allows for larger contiguous blocks of undisturbed forest to be saved through cluster development provisions. However, the Planning Department has presented the arguments for the same density of housing on a clustered development for increasing the density of housing by 28 times. The Maple Grove plan for 279 houses naturally creates more total asphalt and roof area than 9 houses that could have been developed on that site by right. The "less impact" argument isn't about the total amount of impact, but about the intensity of impact per person. 

Despite these arguments, several major environmental and regulatory bodies have disputed the idea that these techniques can substitute for natural wooded areas. Fairfax Water & the NVRC have warned that runoff from new high-density sites could negatively affect drinking water for the nearly million residents that rely on the Occoquan Reservoir for their water supply.

Environmental groups note that large-scale development like the could lead to of tons of additional sediment flowing into the reservoir watershed annually and the Chesapeake Bay. Civic associations and community groups argue that approving high-density projects like Hoadly Square within the Occoquan Reservoir Protection Area (ORPA) "chips away" at the protection district right after its adoption.

Stormwater BMP’s -What you need to know

Last Friday the Potomac Watershed Roundtable met in Frying Pan Park in Fairfax, VA. One of the speakers was Allie Wagner, a Water Resource Planner at the Northern Virginia Regional Commission (NVRC). Allie was there to introduce us to the “Stormwater Best Management Practice (BMP) Maintenance Guidebook.” Recently updated and released. This guidebook is intended to be a  comprehensive resource developed by the Northern Virginia Regional Commission (NVRC) to help private property owners, homeowners' associations (HOAs), and business operators manage and maintain stormwater systems effectively.

The primary purpose of the guidebook is to reduce stormwater pollution—the leading cause of degraded local waterways—by ensuring that BMPs like rain gardens and detention ponds are properly maintained. According to the NVRC, property owner awareness of maintenance responsibilities varies, with owners of "resale" homes often unaware of their obligations compared to HOAs or businesses. Owners are typically responsible for maintaining specific features like rain gardens (ensuring 72-hour drainage), permeable pavers (sediment removal), and clearing vegetation from dry/wet ponds.

The guidebook attempts to provide practical, non-regulatory guidance and includes an introduction to how these systems function and why maintenance is critical. Guidance on how to identify problems, such as clogged pipes, erosion, or standing water.  Tools for budgeting routine and non-routine maintenance expenses. And contact information for local government agencies across Northern Virginia's member jurisdictions

The guidebook contains 14 Detailed BMP Fact Sheets for the most common BMP’s including:

• Dry Ponds (Extended Detention) and Wet Ponds (Retention).
• Rain Gardens (Bioretention Facilities) and Vegetated Swales.
• Permeable Pavement, Sand Filters, and Infiltration Trenches.
• Green Roofs and Rain Barrels.

an example from NVRC

According to NVRC, unmaintained BMPs can fail, leading to:         

• Increased discharge of nutrients, sediment, and toxins into the Potomac River and Chesapeake Bay.
• Potential flooding or erosion on-site.
• Possible violations of local ordinances or maintenance agreements with local governments.

Above and below are examples of two practices. You can find the guide and complete sheets for these practice at this link.

The Heat Island Effect from Data Centers

 (PDF) The data heat island effect: quantifying the impact of AI data centers in a warming world

Marinoni, Andrea et al, The data heat island effect: quantifying the impact of AI data centers in a warming world, March 2026, DOI:10.48550/arXiv.2603.20897 License CC BY-NC-ND 4.0

The article below is excerpted from the papers cited above. 

The urban heat island (UHI) effect plays a key role in the impact of anthropogenic activities on climate change and global warming. In a recent paper Andrea Marinoni at the University of Cambridge and their colleagues saw that the amount of energy needed to run a data center had been steadily increasing and was likely to “explode” in the coming years, so they wanted to quantify the impact.

From humble origins as rudimentary storage facilities to their current status as the lifeblood of the Internet and the Cloud, data centers have become foundational pillars supporting our digital lives.  Yet, their energy footprints and building structures are having an impact on climate change.

The researchers utilized 20 years of satellite measurements of land surface temperatures and cross-referenced the data against the locations of more than 8,400 AI data centers. To eliminate the possibility of impact from the urban heat island effect and recognizing that surface temperature could be affected by other factors, the researchers eliminated data centers in or near urban locations (like Loudoun County) and instead focused their investigation on only on data centers away from populated areas.

The goal was to quantify the land surface temperature increase caused by the establishment of an AI hyperscaler in a location, determine the region of influence of this increase; and estimate the population affected by the temperature increase.

from Marinoni, Andrea et al

They found that the average land surface temperature increase across the data centers was 2.07°C in the months after an AI data center started operation. The land surface temperature increase minimum and maximum were 0.3 °C and 9.1 °C, respectively. The 95th percentile of the land surface temperature increase after the AI data centers began operations is between 1.5°C and 2.4°C.

In addition, the researchers found that the impact of land surface temperature increase impacted a very large area and reached up to 10 km distance from the AI hyperscaler facilities. The data heat island effect seems to reduce its intensity to 30% within 7 km around the data centers. It was pointed out in 2023 by Kilgore et al that "Data centers account for 2.5% to 3.7% of global GHG emissions," which exceeds the greenhouse gas emissions from the aviation industry recorded at 2.4%. 

from Marinoni, Andrea et al

The increasing demand for AI-based services, processes and operations is leading to the proliferation of data centers worldwide that are extremely power hungry. This study shows a rather remarkable impact of the AI data centers on their local regions, which was found to be consistent across data centers worldwide and extends for several kilometers around the AI hyperscalers. The consistency, scale and extent of these effects lead the researchers to suggest that data centers are creating local climate zones - that they call the data heat island effect - is real, significant, and may have a non-trivial impact on global warming and climate transformation.

The data heat island effect could have a significant impact on the on planet since  the trends of data center energy consumption are expected to show a steep growth in the foreseeable future. The data heat island effect could become an additional factor in the changing climate, hence having a robust impact on communities at local, regional, and international level.

Review of Interventions to preserve Groundwater

 Global cases of groundwater recovery after interventions | Science

How communities are reversing groundwater depletion: lessons from 67 global success stories | UC Santa Barbara - Bren School of Environmental Science & Management

Global groundwater depletion is accelerating, but is not inevitable | The Current

Scott Jasechko, Global cases of groundwater recovery after interventions. Science 391,1218-1228(2026).DOI:10.1126/science.adu1370

The article below is excerpted from the article cited above and the UC Santa Barbara press releases linked above.

Groundwater supplies about 50% of the drinking water for the people on our planet. In addition, groundwater also supplies 40% of the irrigation water that feeds the people. Groundwater is essential. However, we are using groundwater at an unsustainable rate-faster than it is being recharged. The result is that mankind is depleting groundwater reserves at an accelerating rate.

In 2024 Scott Jasechko, an associate professor in the university’s Bren School of Environmental Science & Management, and his team at UC Santa Barbara compiled the largest assessment of historical assessment of historical groundwater levels around the world, spanning nearly 1,700 aquifers and 300 million water level measurement. That work presented a picture of dwindling groundwater resources and accelerating declines. But it also found that there are places where groundwater levels have stabilized or recovered. Groundwater declines of the 1980s and ’90s reversed in 16% of the aquifer systems the authors had historical data for. 

That finding served as the basis for the current study which looks at the success stores to understand the strategies that achieved them and might be applicable in other areas. Groundwater is the savings account for our fresh water resources. It is replenished by deposits from rain, snowmelt and surface infiltration. Communities can spend a lot of money building infrastructure to hold water above ground. But if you have the right geology, you can store vast quantities of water underground, which is much cheaper, less disruptive and less dangerous than building dams. The stored groundwater also supports the region’s ecology. Groundwater recharge can store six times more water per dollar than surface reservoirs.

Groundwater recovery can benefit economies and ecosystems. The benefits of groundwater recovery can include (i) halting land subsidence, (ii) slowing seawater intrusion, (iii) reducing drought vulnerability, (iv) restoring groundwater-dependent ecosystems, and (v) improving groundwater accessibility halting land subsidence,

However, there are also downsides to groundwater recovery. In some cases, recovering groundwater levels have introduced new challenges, such as (i) intensified flood hazards, (ii) compromised building stability, (iii) heightened liquefaction risks, (iv) degraded agricultural soils, and (v) increased pollution exposure

Right now, groundwater is being overdrawn. We can address these by enacting policies and creating infrastructure to reduce the demand on groundwater. Alternative water sources can offset groundwater demand or even be used to recharge the groundwater aquifer. The current study tries to organize 67 unique combination of factors to identify trends. They found two-thirds of the cases involved interventions from multiple categories, but finally broke the strategies into three categories.

Alternative water supplies

81% of the groundwater success stories included an alternative water source that helped offset groundwater demands. Professor Jasechko suspects part of this strategy’s appeal is that it requires the least behavioral change, the communities did not have to reduce total water use. But accessing alternative supplies is often expensive and can end up displacing the issue to another location.

Policy and market interventions

In contrast, policy changes benefit from low overhead and energy costs. They also most directly target the behaviors that led to drawdown in the first place. However, they often have major impacts on local economies that have relied on groundwater use for a long time.

Artificial groundwater recharge

Groundwater recharge can eliminate the need to reduce pumping, but the water needs to come from somewhere, and getting it into the aquifer requires energy. In addition, it potentially introduces contaminants into the aquifer.

Dr. Jasechko summarized his findings among the 67 cases of groundwater recovery reviewed into 10 themes. These include (i) the prevalence of cases involving multiple interventions, (ii) the high number of cases involving alternative water sources, (iii) reductions in pumping in some cases, (iv) the importance of sound implementation and enforcement strategies, (v) the possibility for groundwater recovery to begin shortly after some interventions, (vi) the potential upsides to gradual policy implementation, (vii) spatial variability in groundwater recovery trends, (viii) the impermanence of groundwater recovery, (ix) the importance of considering groundwater quality, and (x) direct and indirect impacts of climate variability on groundwater levels.

Jasechko et al

First, two-thirds of the groundwater recovery cases involve two or more of the three types of interventions (i.e., alternative water supplies, policy or market changes, and artificial recharge). Most (81%) groundwater recovery cases involve access to alternative water sources to offset groundwater demands. These alternative water sources can be from nearby surface water,  from recycled municipal water, from interbasin surface water transfers, or from reductions in upstream river diversions to enable more river water to reach a depleted aquifer farther downstream.

Groundwater recovery often coincides with reduced groundwater withdrawals. In some cases, groundwater withdrawals declined after policy . In other cases, groundwater withdrawals declined after the shutdown or relocation of industries or the reduction in irrigated acreage as cultivated lands were urbanized.

The magnitude of groundwater recovery can vary widely within a given area. Further, groundwater recovery is not always ubiquitous, with some monitoring wells recording groundwater storage increases but others capturing continued declines. Ground subsidence from excessive groundwater withdrawal was not reversed, it was only slowed or stalled.

Groundwater-level trends in shallower unconfined aquifers were found to differ from deeper confined aquifers because shallower and deeper aquifers often have different storage coefficients and different rates of groundwater recharge and groundwater withdrawals. The examples discussed in the paper (especially the detail provided on Be

This study is not a guarantee that any particular intervention will work elsewhere. It does not perform causal inference, but it provides what Dr. Jasechko calls a "menu of options" for resource managers, backed by documented outcomes from real-world cases across six continents. Dr. Jasechko’s collaborator, UC Santa Barbara professor Debra Perrone, is now working to build a comprehensive database of all locations where interventions have been attempted, including those that failed, which would enable more systematic analysis of what works and why.

Test Your Well Annually

Private wells are not regulated under the Safe Drinking Water Act; the homeowner is entirely responsible for monitoring water safety.  Many pollutants that can impact your health, such as Nitrates and E. coli, have no taste, smell, or color. An annual water test acts as a "health check-up" for your well, helping to identify problems early. The U.S. Environmental Protection Agency, the CDC, the Virginia Department of Health and various other organizations recommend annual testing, but most homeowners do not. There is no requirement in Virginia. I test my well every year, and the Virginia Household Water Quality Program run annually by the Extension Office is one of the cheapest ways to get it done.  Judging by the number of people who participate in the clinic each year (a hundred or so out of 16,000 of well owners in Prince William County) most people do not test their well regularly. You should.

 Last Wednesday morning following the instructions from the Extension Office, I collected water samples from my kitchen sink and put the sample bottles in the refrigerator. Then after having coffee and feeding the pets, I drove the samples (in an insulated lunch pack on ice) to the Extension Office in Manassas. Once a year the Virginia Cooperative Extension in Prince William County holds a well water testing clinic where water samples are tested for: iron, manganese, nitrate, lead, arsenic, fluoride, sulfate, pH, total dissolved solids, hardness, sodium, copper, total coliform bacteria and E. Coli bacteria all for the low cost of $70. Though you missed the clinic this year, you can email    and get your name added to the notification list. Trish Westenbroek is doing an excellent job of coordinating the program and sending out reminders, so email PWestenbroek@pwcgov.org  and ask to be put on the list and you will get a notification next winter to sign up.

While the U.S. Environmental Protection Agency (EPA) regulates public water systems, the responsibility for ensuring the safety and consistent supply of water from a private well belongs to the well owner-in this case me. These responsibilities should include knowing the well’s history and planning for equipment replacement, testing the water quality annually (or more often as needed), and having the well system and its components inspected regularly by a well driller licensed well-service company. 

In Virginia installation of private wells is regulated by the Department of Health, responsible for approving the location of a well, inspecting the well after construction to verify proper grouting and adequate water yield, maintaining records of the well driller’s log, verifying the most basic potability of water by requiring at a minimum bacterial testing after completion. Then you are on your own to do what you deem best.

If your home has a drinking water well that is contaminated, it could significantly impact your health and the value of the property. When you buy a home lenders require that a well be tested for coliform bacteria contamination, nothing more. For many homeowners this was the only time their well was ever tested. Total coliform bacteria is always present in manure and sewage, but is also present in soil and vegetation and surface water. The presence of coliform bacteria can mean that surface water is getting into the well either directly through a failing casing or grouting or improper construction or well cap or by other means. Absence of coliform bacteria only means that water is not contaminated by septic and surface runoff, but the water might be contaminated from other sources.

Due to its protected location underground, most groundwater tends to be clean and free from pollution. Typically, the deeper the well the less likely is it to be contaminated; however, there are a number of threats to drinking water: improperly disposed of chemicals (pesticides and oil poured down the drain of a home with a septic system); animal wastes; pesticides; human wastes (that nearby septic system); wastes buried underground or leaking fuel tank; and naturally-occurring substances can all contaminate drinking water and make it unsuitable for drinking or make the water unpleasant to drink. Homes built on former disposal sites- farm dumps, landfills or former military operations are particularly susceptible to contamination. Former agricultural properties should be tested for pesticides, fuels and solvents because farmers often have fuel tanks and repaired farm equipment with solvents that were improperly disposed of over the years. Hopefully, all those tests were done before you bought the home (I know I did).

 The nightmare scenario is what happened in Sterling, Virginia. The short story is that for twenty- or thirty-years homeowners in that community in Loudoun County were drinking water contaminated with TCE and its degradation products. The homes had been built on an old landfill and back in 1988 the Loudoun County Department of Health and the EPA had found traces of TCE, its degradation products and pesticides in three residential wells, but because the contamination was below the regulated maximum contaminant level (MCL) no further investigation was carried out. Apparently, the oddity of finding a solvent in groundwater in a residential community did not immediately prompt further investigation. The water was within safe limits and thus was fine.

However, the water in the neighborhood was not fine. In 2005, 68 more wells (in the community) were tested by the Health Department. “Forty-five wells tested positive for TCE; 17 of these wells contained concentration of TCE above the maximum contaminant level (MCL) of 5 micrograms per liter (mcg/L) while 28 wells contained TCE, but below the MCL.”  The site was declared a CERCLA (Superfund) site in 2008. Between 1988 and 2005 no testing was done on the individual homeowner wells. The water was consumed by the young and old and the homes were bought and sold. If your home had been declared within a Superfund site, it is very likely that the value of the home would be impacted.

Everything that is known about the groundwater in Prince William County is because a study of the groundwater was performed by the U.S. Geological Survey (USGS) in 1991 to study the extent of TCE contamination from the Superfund site in Manassas. They did not test every inch of the county nor look for other contaminants in the groundwater. Their study was designed to find the extent of the TCE contamination plume and where else the contamination might have spread because when you test groundwater and its flow it often surprises.

To be prudent and smart you need to test a well for likely sources of contamination. When I was working as an Environmental Engineer, the biggest challenge was to adequately research the history of a property and then test the soil and groundwater for contamination in the areas most likely to be contaminated. Testing is expensive, so it is virtually impossible to fully test soil and groundwater for everything, and it is very easy to miss the contamination if the study is not planned properly and you do not understand the specific geology. With substances like PFAS, the sensitivity of the tests has increased tremendously as has the knowledge that health can be impacted by extremely low levels of PFOS and PFOA- in the single digit parts per trillion.

When buying a home with a well, you do not have any of this information or resources available to you. Neighbors can be useful or just have no understanding of environmental and groundwater issues and tell you nonsense they’ve heard. If someone asked me about groundwater in my community or my opinion about any specific well, I would tell them, but they would not know my level of expertise. While there are some good historical records available for industrial and commercial properties there is very little information available for residential properties. The department of health often has some useful information about water quality in the county and septic systems but rarely has any water analysis data available. Though, it was a Department of Health employee who originally found the Prince William County TCE contamination.  

Your best option is to do a broad scan of the well water quality. There are screening packages available from U.S. EPA certified laboratories like  National Testing Laboratories that screen water wells for all the primary and secondary contaminants in the Safe Drinking Water Act. The WaterCheck with pesticides package from National Testing Laboratories is a broad stroke test, testing the water for 103 items including Bacteria (Total Coliform and E-Coli), 19 heavy metals and minerals including lead, iron, arsenic and copper (many which are naturally occurring, but can impact health); 6 other inorganic compounds including nitrates and nitrites (can indicate fertilizer residue or animal waste); 5 physical factors including pH, hardness, alkalinity; 4 Trihalomethanes (THMs) and 47 Volatile Organic Chemicals (VOCs) including Benzene, Methyl Tert-Butyl Ether (MTBE) and Trichloroethene (TCE). The pesticide option adds 20 pesticides, herbicides and PCBs.  This testing can be done for a few hundred dollars. I am still waiting to find an affordable and accurate PFAS screen and test, but I’m afraid I will need to wait for the knowledge about potential contaminants to the groundwater and testing to get there.  Prince William county has talked about doing a groundwater study for about a decade now and we’re still not there.   

I’ve done that kind of “full analysis” on my well a few times. These days I test my well annually in the annual water quality clinic sponsored by the Extension office. Groundwater quality is driven by geology, well construction and condition, nearby sources of groundwater contamination, and any water treatment devices and the condition and materials of construction of the household plumbing. Year to year, outside sources of groundwater contamination are not likely to change except with changes in land use. Thus, it is not necessary to test for industrial contaminants every year. To ensure my drinking water remains safe it is important to maintain my well (I replaced the cap six years ago when I replaced the pump), test it regularly and understand your system and geology. I do not have any water treatment in my house; I drink the water just as it is from the ground. If however, you have water treatment equipment in your home you might want to test the water before and after the treatment equipment each year to make sure you have the right equipment for your water and that it continues working properly.

Salt the Fingerprint of Mankind

Inland freshwater salinization historically was once thought to be a problem only in areas with arid and semi-arid climates, poor agricultural drainage practices, sodic soils and saline shallow groundwater. Certainly, when I was in school that is what we were taught. Today, inland freshwater salinization is on the rise across many cold and temperate regions of the United States.  

Inland freshwater salinization is particularly notable in the densely populated Northeast and Mid-Atlantic like here in Northern Virginia, and agricultural Midwest regions of the country. It turns out that salt is the fingerprint of mankind. We have disrupted the Earth's natural salt cycle in every activity from the first seeds of agriculture to modern high-tech living. The presence of mankind is marked by salt- the fundamental change in the chemistry of the world’s inland waters and soils.

The first mark of this fingerprint appeared in ancient Mesopotamia, the Cradle of Civilization. To feed growing populations, the Sumerian people of Mesopotamia (Modern day Iraq) engineered massive irrigation systems for their arid lands.  They used flood irrigation and this over-irrigation of their caused the water table to rise, wicking naturally occurring underground salts to the surface via capillary action.

 As water evaporated, it left behind a salt crust. Between 2100 BC and 1700 BC, soil salinity forced a shift from wheat to the more salt-tolerant barley, eventually leading to agricultural collapse and the migration of 60% of the population. This pattern repeated itself across other civilizations across the globe.

As humanity expanded, and our population grew, so did the  ways that the salt footprint that traveled with our communities grew- through intensified land use and waste disposal.  In regions like Australia, clearing deep-rooted native trees for shallow-rooted crops stopped the natural drawdown of groundwater, allowing saline water tables to rise and drown the soil in salt. The land application of manure and modern fertilizers adds significant salt ions (like potassium and chloride) to the soil, which eventually leach into groundwater and rivers.

Mankind has a taste for salt.  Wastewater from growing urban centers carries concentrated salts from our diets.  This "fingerprint" is becoming even more indelible as we more widely adapt potable water reuse—recycling wastewater directly back into our taps. While recycling is a necessity to supplement supply for regions becoming more water scares or increasing population, it creates a salt loop that is difficult and expensive to break. Because traditional wastewater treatment cannot remove salts every time we use water, we add salt—from our diets, soaps, and water softeners. When that water is recycled and sent back to homes, those salt levels naturally rise for each cycle. To strip this salt out, cities must use Reverse Osmosis (RO). However, RO is energy-intensive and produces a highly concentrated "brine" waste that is difficult to dispose of without harming local ecosystems.

The scientists at the Occoquan Watershed Laboratory believe that the sodium in UOSA’s wastewater comes from a variety of sources -watershed deicers, water treatment processes (both household and Fairfax Water), household products, commercial and industrial discharges, drinking water treatment, and wastewater treatment. On the basis of data provided by UOSA they estimate that 46.5% of the daily sodium mass load in UOSA’s reclaimed water is from chemicals used in water and wastewater treatment (for pH adjustment, chlorination, dichlorination and odor control), a single permitted discharge from the Micron Semiconductor facility and human excretion (our diets are salty). That still leaves 53.5% of the salt, and its source remains unknown.  

The salt levels are also rising in the rivers and streams that provide water to our region. In the modern era, the salt fingerprint has become more complex, involving a "chemical cocktail" of salts used for safety and comfort. For example, there is salt in soaps, cleaners, and water treatment chemicals.  To ensure winter safety, millions of tons of chloride-based salts are spread on roads annually. This salt doesn't just disappear; it migrates into lakes and streams, where it can persist for decades.  

In many regions, household water softeners are the largest source of chloride to wastewater treatment plants, and also to the groundwater. In Prince William County water softeners in homes connected to public water supply are not tracked. However, the VA Tech tracks water softeners used by well owners. In Prince William there about 16,000 private wells and over 40% are estimated to have water softeners. Each one of these water softeners discharges 800-1,000 pounds of salt.  This salt is discharged directly into freshwater ecosystems.

Globally, human-caused salinization affects an estimated 2.5billion acres of soil—an area the size of the United States. It isn't just a local agricultural nuisance; it is a chronic environmental "syndrome" that mobilizes other toxins like lead and mercury, threatens drinking water, and permanently alters the chemistry of our planet's freshwater.