My Well Check Up

My well in its safety enclosure next to the driveway

After a series of calls from people whose wells had problems, I began to think that it would be a good time to check the condition of my well and equipment, before winter. In addition, I had wanted to get a new well cap since the last time I chlorine shocked my well and had difficulty resealing the well. So after calling around to state licensed well service companies I scheduled a well check up with Bell Pump & Well out of Fairfax Station. In Virginia a well driller should have at least a Class B contractor license and the service provider must be Department of Professional and Occupational Regulation, DPOR, certified Well Water Providers. Since 1992 private drinking water well construction and service has been regulated in Virginia and well drillers and well service companies have to be licensed. In many other places well drilling and water wells are still not regulated. Bell Pump & Well is not a well driller, they service, repair and replace the mechanical components of a well.

As a well owner you need to know your well. Start with the “Water Well Completion Report” that must be filed when a well is drilled in Virginia. This report can tell you the age of the well, the depth of the well and casing, the approximate water zones and the yield at completion. These are the most basic facts needed to evaluate a well and water system. These reports are housed at the County Health District offices. From my report I know that my well is 150 feet deep and was grouted to 60 feet below grade. Back in the fall of 2004 when the well was drilled, the water zones were at 121-122 feet and 143-144 feet below grade. The static water level is listed at 30 with the units illegible and the stabilized yield is 60 gallons per minute after 2 hours. You read that right, 60 gallons per minute recharge rate. The property in a fractured rock system overlying the Culpeper groundwater basin has amazing groundwater flow.

The Prince William Health District rule of thumb is 5 gallons/minute is a safe yield to supply on-demand water for a typical household, but homes can have much lower yielding wells and still serve a household. However, be aware that over time the static yield of most wells fall. Groundwater typically enters a well through fractures in the bedrock and overtime debris, particles, and minerals clog up the fractures and the well production falls. According to Marcus Haynes at the Prince William Health District that drop could be 40-50% or more over 20-30 years. A low yielding well might have a functional life of only 25 years. My well is unlikely to have a noticeable reduction in yield because the fractured rock system does not typically clog with debris. The functional life of my well could easily exceed my lifetime.

If you have an older well, or you are buying a home with an older well having a well driller perform an accurate assessment of the well’s capacity would be important. A well recharge can be estimated by running water from the pump and measuring the top of the water level in the well. If it does not change, then the well recharges fasters than the pump rate. If the level is falling then the each foot in a typical 6 inch cased well represents about 1.5 gallons. A more accurate rate to determine the recharge rate is to use a compressor to blow all the water (and deposits at the bottom of the well) out of the well and time how long it takes the well column to recharge. When I last chlorine shocked my well, the water level was visible less than 2 feet down and even with running both hoses, I could not drop the water level. The recharge was too fast to clock. It costs about $200-$300 to have a well driller to do a flow test on your well and determine the water level. Since I could see my water level, and the recharge was faster than I could clock I passed on having that done and was pleased that the well itself was in good condition.

I had Bell Pump & Well examine the condition of the casing, wiring, replace the cap pump and check the well components in the house- the pressure tank and switch. The check-up cost under $200, the well cap replacement was extra. The pump should be checked for amp load, grounding, and line voltage, and the pressure tank checked for psi, a functioning pressure switch (check the contacts for corrosion), and checked for leaks.

I received a one page report from Bell Pump & Well that tells me I have a ¾ horsepower submersible pump. The pump is probably a Goulds’ Pump since the pressure tank installed at the same time is labeled Goulds and when sold together they usually label the pressure tank with the pump brand. (Gould Pump does not actually manufacture pressure tanks.) It is a good brand of pump, but there are cheap versions with plastic fittings and I would assume that my pump was “builder grade” like everything else in this house and will only have an average lifespan. The pressure switch is functioning properly cutting on a 55 psi and off a 75 psi. The higher range setting is to up the water pressure slightly. The pressure tank had a good cycle and the pressure switch was in good condition.

Out at the well, Bell Pump & Well noted that the well is a 6 inch drilled well that the well meets code. The pump amperage load was within the normal operating range and the line voltage was normal. There were no signs that the pump motor was wearing out. The most likely pump failure I am likely to see is from a lightning strike- Steel sticking out in the lawn and running sixty feet below ground is a very attractive lightening target. Based on my well check-up, I’m good to go for the winter. I will be testing my water quality in the spring when the Virginia Cooperative Extension (VCE) Office will be hosting a drinking water clinic for well, spring and cistern owners in Prince William County as part of the Virginia Household Water Quality Program. When a well is drilled the only water sampling that takes place is for a coliform bacteria test. There are many chemicals and naturally occurring contaminants that could make water unpalatable or unhealthy. The Virginia Household Water Quality Program recommends that water be analyzed for: iron, manganese, nitrate, lead, arsenic, fluoride, sulfate, pH, total dissolved solids, hardness, sodium, copper, total coliform bacteria and E. Coli bacteria (if coliform is present). That can add up to quite a bill, but the analysis is subsidized by the state program and will cost only $49.

Test and Think Before Treating Well Water

When I first bought my home here in the Rural Crescent of Prince William County several people tried to sell me water treatment systems, from the carpeting contractor who wanted to also sell me a whole house filter to the water softening system salesman offering “free water testing.” The free testing offered by these companies usually only tests for hardness and other contaminants that they sell treatment systems for, but there has recently come on the market home testing kits that are quite good and can test wells for health related impurities. However, because I had fully tested the well water for every primary and secondary drinking water contaminant before purchase and liked the taste of my water, I knew that water treatment was not necessary.

Private drinking water wells should be tested annually for bacteria and every 1-3 years for other common regional groundwater contaminants especially if you install treatment systems. Groundwater is dynamic and can change over time, and it is important to make sure that any treatment is still appropriate and effective. Though I know that there is a tendency to not test water because you worry about what you might find, you need to monitory your water quality. Water treatment systems are not an install and forget piece of equipment, they are systems that need to be maintained and adjusted to keep the water within ideal parameters. Improperly treated water can be as problematic as not treating water.

The Virginia Cooperative Extension (VCE) Offices in Virginia occasionally holds drinking water clinics for well, spring and cistern owners as part of the Virginia Household Water Quality Program. The VCE subsidizes the analysis cost for these clinics and Prince William Extension is planning on holding its next clinic on March 31, 2014. Currently, samples are analyzed for: iron, manganese, nitrate, lead, arsenic, fluoride, sulfate, pH, total dissolved solids, hardness, sodium, copper, total coliform bacteria and E. Coli bacteria at a cost of $49 to the well owner. This is far from an exhaustive list of potential contaminants, but with one or two exceptions these are the most common contaminants that effect drinking water wells in Virginia. These are mostly the naturally occurring contaminants and common sources of contamination: a poorly sealed well or a nearby leaking septic system, or indications of plumbing system corrosion from slightly acidic water.

There are other contaminants that can be found in ground water in certain regions that can cause illness when exposed to small amounts over long periods of time Uranium is an example. There are also nuisance contaminants for which there is not an approved EPA methodology, iron bacteria is an example. The Virginia Household Water Quality Program has been sponsoring water clinics and collecting well data in Virginia for years. They have used their database to expand their knowledge of regional water quality problems and natural contaminants. Water analysis should be performed before any treatment is considered to make sure the selected treatment is necessary and appropriate. Remember a treatment system not only has to be maintained, but curing one problem may cause another.

I have tested my well at different times of year and sometimes my water is harder than others, but also there are times when my sulfate levels have been higher than others. According to the water clinic statistics, Prince William County has very high naturally occurring levels of sulfate and elevated levels are not uncommon. The EPA guidance for sulfate is 250 ppm for taste, but may be unnoticeable at higher levels, but truly excessive levels can have a laxative effect. Hydrogen Sulfide gas (H2S) gives water that awful “rotten egg” taste and smell and can render water undrinkable because of the taste and smell. Unless you have hydrogen sulfide, sulfate concentrations can be ignored at levels up to (and possibly beyond) twice the EPA secondary limit.

Hydrogen sulfide can never be ignored and is probably the reason some wells are considered to have bad water. Hydrogen sulfide can end up in your tap water by four different routes: (1) It can occur naturally in groundwater in oil rich shale and coal seams. (2) It can be produced within the well or plumbing systems by sulfur reducing bacteria. (3) Hydrogen sulfide can form in hot water heater by either supplying a pleasant environment for the sulfate reducing bacteria or by the reaction of magnesium rod intended to prevent corrosion of the heating tank with the sulfate in the water. (4) Hydrogen sulfide gas can be caused by contamination of the well with septic waste. Systematic testing can identify the cause and cure.

Hydrogen sulfide created by sulfur reducing bacteria “eating” the sulfate can be appear over time after installing a water treatment system. According to the EPA, sulfur-reducing bacteria pose no known health risks, but can make the water and entire home smell of rotten eggs. Sulfur-reducing bacteria live in oxygen-deficient environments such as deep wells, plumbing systems, water softeners, and water heaters. Often these bacteria flourish in plumbing and water softening systems. Sulfate reduction can occur over a wide range of pH, pressure, temperature, and salinity conditions and produce the rotten egg smell and the blackening of water and sediment by the formation of iron sulfide if iron is also present in the groundwater or plumbing system. If you do not have a hydrogen sulfide problem, but do have elevated levels of sulfide, think very carefully before you install any treatment system where the sulfur reducing bacteria or iron reducing bacteria might thrive.

Low pH water or acidic water is fairly common in the Tidewater portion of the county east of the Fall Line. The pH of water is a measure of the acidity or alkalinity. The pH is a logarithmic scale from 0 – 14 with 1 being very acidic and 14 very alkaline. Drinking water should be between 6.5 and 7.5. For reference and to put this into perspective, coffee has a pH of around 5 and salt water has a pH of around 9. Corrosive water, sometimes also called aggressive water is typically water with a low pH. (Alkaline water can also be corrosive.)

Over time low pH water can corrode metal plumbing fixtures causing lead and copper to leach into the water and causing pitting and leaks in the plumbing system. The blue/green staining on plumbing fixtures observed in some older homes is caused by the slow corrison of the old copper pipes. These homes which are now quite old (copper piping has not been used for decades) typically experience occasional plumbing leaks. The presence of lead or copper in water is most commonly leaching from the plumbing system rather than the groundwater.

Though acidic water is easily treated using an acid neutralizing filter, by now it is probably too late to save your pipes from damage. Neutralizing filters use a granular marble, calcium carbonate or lime. If the water is very acidic a mixing tank using soda ash, sodium carbonate or sodium hydroxide can be used, but this can be overkill in many homes. The acid neutralizing filters will increase the hardness of the water because of the addition of calcium carbonate creating a new set of problems to address. The sodium based systems will increase the salt content in the water. Water softening systems are used to address hard water are basically an ion exchange systems that can add even more sodium to the water and may shorten the life of your septic drain field.

Wells, Geology and Contamination

from USGS

A well is simply a hole dug or drilled into the ground from which water can be removed. The hole is called the borehole and is lined with a well casing, which is typically a plastic or metal pipe. The well casing prevents the side walls of the borehole from collapsing into the well and closing the hole. The casing is sealed into place with grout which is usually neat cement or bentonite that was pumped into the annular space between a well casing and the borehole. This grouting seals the well and prevents water from flowing into the well directly from land surface down the side of the well casing pipe or from the shallowest part of the aquifer where the water quality may be less desirable.

Depending on geology, the casing will be open at the bottom or perforated at a specific depth with a screen, allowing water to flow into the well where it can be pumped to the surface. In sandy soils well screens are common. In fractured rock systems and bedrock screens are not necessary on low volume domestic wells. In clay or loam coarse sand or gravel can be placed around the well screen to help improve the flow of water into the well. These sand or gavel packs create larger pore spaces for water to accumulate. Gravel or sand packs are rarely used for domestic wells.

In the United States almost half of all drinking water is supplied by wells. About a third of the population obtains its drinking water from public supply wells which they never think about, and about 15% of the population obtains their household water from private domestic wells. Domestic well owners need to think about their wells and the groundwater that supplies them. Domestic wells have pumps that can pump 10-15 gallons a minute into the pressure tank when needed for household use. These pumps draw groundwater from the area immediately surrounding the well. Depending on the depth of the well and the local geology groundwater drawn into a private domestic drinking water well is typically young water-it could be weeks, months or several years old.

Typically rain water and snow melt percolate into the ground and the deeper the well the further away is the water origination and the older the water. The groundwater age is a function of the depth of the well, the geology of the area, the precipitation, recharge of the aquifer and pumping rates of the aquifer that control the rate of flow of water to a well. The age of the water in an aquifer provides insight into the likelihood of contamination from both anthropogenic and natural sources. Very young groundwater that has recently infiltrated into the aquifer is more vulnerable to contamination from human activities near the land surface than older, deeper groundwater that has had more time to be filtered by soils. Old groundwater, however, is not necessarily free of contaminants. The older groundwater can contain naturally occurring chemical elements and contamination from years past. The land surface through which groundwater is recharged must remain open and uncontaminated to maintain the quality and quantity of groundwater.

Though the most common sources of pollution to groundwater supplies come from two categories; naturally occurring and human activities, groundwater and domestic well water vulnerability to contamination depends on three factors:

1. The presence of man made or natural contaminant sources; for example, a failing septic system or chemicals poured down the drain, or underlying sediments can be sources of contaminants entering groundwater. From the underlying rocks radionuclides and heavy metals can enter the groundwater. There are areas with natural occurring arsenic, cadmium, chromium, lead, selenium and fluoride. 
2. The natural processes in the subsurface that can filter or cleanse the groundwater; for example, microorganisms can break down some chemical contaminants in groundwater like nitrate, contaminants can attach to soil particles and unsorted sediments can cause dispersion of contaminants as they move through an aquifer. 
3. The ease with which water and contaminants can travel to and through an aquifer; for example microorganisms in the soil and from wildlife can travel into groundwater supplies through cracks, fissures, other pathways of opportunity or even through sedimentary and basaltic rocks that are highly fractured and overlain by a thin cover of overburden, while a dense clay layer can reduce groundwater vulnerability by acting as a barrier to the movement of water and contaminants.

The vulnerability and water quality of a well can be vastly different from the quality and productivity of nearby wells. The most common sources of pollution to groundwater supplies come from two categories; naturally occurring ones and those cause by human activities. Naturally occurring contamination are those that are produced from the underlying soil and rock geology and wildlife. Once within an aquifer, contaminants that dissolve in water will travel with the flowing groundwater. What happens next is dependent on the chemical properties of a contaminant, the geology of the area and the flow rate of groundwater. Natural processes such as sorption/desorption, dissolution/precipitation, ion exchange, or biodegradation can reduce contaminant concentrations to effectively clean the groundwater. Many contaminants in the shallow groundwater remain in solution because of presence of oxygen, and the short travel times between the water table and the domestic wells allows contaminants to easily reach the well. In addition, a well might have one or more pathways of opportunity. One of the most common contaminant pathways is the failure of the grouting on the well casing allowing rainwater and snowmelt (carrying dirt and other contaminants) directly enter the well.

Nitrate concentration are often elevated in shallow groundwater because of agricultural and suburban development. Bacteria and nitrates contamination to groundwater can be caused by human and animal waste. In our own neighborhoods septic systems, horses, backyard poultry can cause these problems perculating into the ground or finding an opportunistic pathway through a fissure or other geological entry. On a regional level small lots and dense population of septic systems or large animal or fertilized farm operations can cause problems. Heavy local use of pesticides for ornamental gardens, leaks from underground fuel tanks can be sources of contamination. Households can introduce solvents, motor oil, and paint, paint thinner, water treatment chemicals and others substances by not maintaining our septic systems, or pouring chemicals into the ground or down the drain. Groundwater-quality protection depends on the entire community, what my up gradient neighbor does could impact my water quality. If residents and businesses take steps to reduce input of anthropogenic contaminants to the groundwater, water quality can be improved because of the short travel times between the water table and the well. The opposite is also true. 

from USGS