Frequently Asked Questions

Groundwater Basics

Water Quality Concerns


Groundwater Basics

  • What is groundwater?
    • It is slow-moving water that passes through the tiny spaces in soils and gravels, the fractures in rock layers, or through channels and caverns in limestone or dolomite. The spaces where groundwater moves are called "aquifers."
  • Who uses groundwater?
    • Groundwater is such a part of our lives that we take it for granted. Some people don't know that the water they are consuming is derived from groundwater.
  • Where does my well water come from? What are the groundwater and geological characteristics of the different parts of Virginia?
    • Groundwater moves laterally to pumping wells. The "recharge area" for a well depends on how deep the well is and in what types of rock or sediment it is located. Throughout Virginia's five major physiographic provinces, shallow dug or bored wells are not much deeper than the water table and usually obtain water that infiltrated relatively nearby, typically less than a mile. Recharge areas for deeper wells are more variable. Recharge to wells drilled into rocks in the Piedmont and Blue Ridge also is fairly localized. Wells drilled into rocks in the Valley and Ridge sometimes intercept water that has traveled as far as several miles, particularly in limestone areas with large cave systems. In the Coastal Plain, wells drilled into deep sand layers can intercept water that traveled several tens of miles, from recharge areas that may be several counties away.
  • What is in my well water and how did it get there?
    • Several chemical constituents called "major ions" originate from the mineral grains in the rock or sediment with which groundwater is in contact, and usually make up the bulk of the dissolved material. In Virginia, especially in limestone areas of the Valley and Ridge, "hard" water can have high concentrations of certain major ions that can cause scaling of plumbing fixtures and other problems. Other "minor" elements also originate from the minerals that groundwater contacts, but are at lower concentrations because they do not dissolve easily or are less abundant in the minerals.
    • Nevertheless, some problems commonly result from certain minor elements. Large amounts of iron in the rock in some areas, particularly the Piedmont and Blue Ridge, result in iron "staining." Sulfide in groundwater in parts of the Valley and Ridge where coal or natural gas is present produces an obnoxious odor.  Water treatment systems are advertised in the yellow pages; these systems can often improve the overall quality of your tap water.
    • Groundwater also can be contaminated by human activities. Bacteria from septic systems, and nitrate from both septic systems and fertilizer applications, are among the most common contaminants. The potability, suitability for drinking, of a private well is the responsibility of the homeowner.  Homeowners should be diligent in maintaining their well, the area around their well, and in servicing their on-site sewage disposal system.  Poor well construction, where surface water can infiltrate the well casing, is often noted as a cause of localized well problems.  Homeowners should keep files on their well construction, maintenance issues, location of possible sources of contamination, water analysis, etc.  Sampling and analysis of private wells is the responsibility of the homeowner.  Laboratories can be found in the phone book or on the internet under "Laboratories Testing".
  • How are surface water and groundwater connected?
    • Most groundwater comes from precipitation that falls on "recharge areas" or from the flowing water in rivers and streams. (Pollutants that it encounters on the way can be carried into the aquifer.) Most groundwater doesn't just stay underground until a well is dug, though. On average, about 30 percent of stream flow is from groundwater; it may reach 100 percent during droughts. Streams, lakes, springs, and wetlands continuously receive groundwater discharge. (Source: Protecting Virginia's Ground Water ™1997 Virginia Water Resources Research Center)
  • How can development be planned to protect the groundwater supply?
    • For existing water supply wells, the groundwater flow system that provides water to the wells needs to be understood in sufficient detail to identify the recharge areas. Boundaries of flow systems, which often encompass considerably more than the immediate vicinity of the wells, need to be determined to delineate the area through which groundwater flows before reaching the wells. Activities that are potential contaminant sources need to be managed in recharge areas, and practices that reduce the potential for contaminant release need to be adopted. For proposed water supply wells, the ability of the flow system to yield more water beyond the existing demand needs to be determined. Conservation measures may be needed to expand the supply. Proposed well site locations need to be evaluated for (1) possible interference with existing water supply wells and surface water systems, and (2) existing potential sources of contaminants to the proposed wells. For both existing and proposed wells, the element of time needs to be considered; groundwater travel times are generally from years to decades, and planning for groundwater protection is necessarily long term. Ultimately, limits on the extent and manner of development need to be planned.
  • Can a city's, county's, or town's comprehensive plan be a useful tool for groundwater protection?
    • The comprehensive plan is a logical starting point for groundwater protection since it provides the foundation for all programs and land use management tools at the local level. It sets forth goals and policies to guide future land use and development policies of a community. In the event that a community's groundwater protection program is ever challenged, one of the best defenses will be a well formulated comprehensive plan which provides the basis and rationale for the challenged action.
    • Virginia law requires that local governments prepare comprehensive plans and update them at least once every five years. Provisions were added to the code in 1988 and 1990 to indicate that jurisdictions shall study matters such as groundwater and geology in preparing their plan and may subsequently adopt provisions to protect the groundwater resource. These provisions apply both to private wells serving individual households and businesses, and to various types of public wells.
    • Area-wide planning studies for public wells might examine land use types and densities in relation to groundwater vulnerability, and result in designating areas where conservation and protective measures are needed. This evaluation process can help localities to understand the nature of any potential threats to their drinking water supply, and provide an impetus for establishing goals to protect these valuable resources.
    • Site specific studies around individual wells can provide the basis for planning and goal setting on a site by site basis. In some cases, the individual results may suggest that the community revisit its development concepts and policies in order to address recurrent issues or problems.
    • Localities that fall under the Chesapeake Bay Preservation Act are already familiar with using comprehensive plans to evaluate development patterns and their impact on water quality protection. In order to comply with the Act, Chesapeake Bay jurisdictions must prepare comprehensive plans which identify the relationships between water quality protection and other land use considerations. The Chesapeake Bay Local Assistance Department's Local Assistance Manual includes a section on wellhead and groundwater protection and provides useful guidance for all localities regardless of location.
  • Can a locality's Capital Improvements Program (CIP) play a role in groundwater protection?
    • Often included as an element in a comprehensive plan, a capital improvements program - or CIP - provides a schedule for financing, constructing, repairing, or replacing major public facilities needed by a locality. Section 15.2-2239 of the Code of Virginia permits a locality to prepare a capital improvements program based upon its comprehensive plan, but does not make it mandatory. It states that:
    • Capital improvements planning is an important component of a groundwater protection program, given the role that local government infrastructure plays in fostering development. In planning areas for future development, local governments must ensure that there will be adequate potable water supplies. If groundwater is to be relied on as the primary source of drinking water, this means considering the need for and the location of new wellfields. In addition, furnishing infrastructure to a region, or not doing so, can act as a means of locating future development in areas away from wellheads in order to lower vulnerability to groundwater contamination. The CIP also plays a role in contingency planning. In the event that a public well needed to be phased out, replacement supplies - either from surface or groundwater sources - would need to be identified, planned and linked to a source of funding.
  • My community has zoning and subdivision regulations--can these be used as groundwater protection tools?
    • The ability of a locality to control land uses through zoning can provide a strong basis for a successful groundwater protection program. Along with the part of the code dealing with the comprehensive plan, Section 15.2-2283 of Virginia's zoning law was also amended to incorporate language allowing localities to include "reasonable" zoning provisions to protect groundwater.  The applicable language is shown in bold here. Wellhead protection is a prime example of the type of program envisioned when the state enabling laws were expanded. While the term "reasonable" is not defined in the statute, it can be assumed that a reasonableness standard applies to all zoning and, therefore, that groundwater protection measures must be no less reasonable than other zoning measures.
    • Zoning can be used as a tool to protect wellhead areas from contamination in a number of ways, depending on the level of development surrounding the wellfields. It is most effective for directing future development in a planned fashion - it is much less effective once an area is developed. This is a good reason to take a preventive and anticipatory approach in dealing with wellhead areas.
    • If a wellhead area is currently undeveloped, the most direct approach for protecting it would be to zone the wellhead area for uses compatible with groundwater protection. Other uses, such as certain commercial or industrial activities, could be directed to other locations where the groundwater and surface water resources may be less vulnerable.
    • In addition, there are several specific types of zoning controls that are especially applicable for wellhead protection, although others may be appropriate as well. The techniques that will be discussed here are: overlay zones, density restrictions and cluster development, conditional zoning and special permits, and subdivision requirements.
  • Are there other tools that can be used for groundwater protection?
    • Yes, these include conservation easements, purchase of development rights, water conservation, household/farm/business hazardous waste collection, "Best Management Practices" (BMPs), and cost share approaches.
    • Innovative public education programs on groundwater topics can develop interest in groundwater. These can cover the role of groundwater in meeting public needs, methods for preventing groundwater contamination, and helpful actions for residents, property owners, and business managers to take.

    Water Quality Concerns

    • Where can I find more information about groundwater quality?
    There are many sources of contaminants in the environment, both natural and manmade.  The manmade contaminants, often associated with land use management decisions, are the focus of many regulatory and non regulatory programs at the Federal, State, and Local level.  The following links are provided, in no particular order, to enlighten the general public on some of these contaminant sources and the programs that address them.
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Virginia Department of
Environmental Quality
P.O. Box 1105
Richmond, VA 23218
(804) 698-4000


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