Water Quality and Supply FAQ

Home treatment units may improve flavor or odor, but they do not boost safety. Lack of maintenance might cause bacteria to proliferate in the treatment system and taint the water. Before buying a home water treatment device, read the product information. Follow manufacturer directions for operation and maintenance and change the filter regularly. Certified home treatment devices should have an NSF mark. Visit the EPA's website for more information. 
 

Bottled water isn't always safer than tap. The EPA imposes stronger requirements for our treated drinking water than the Food and Drug Administration does for bottled water. When buying bottled water, consumers should study the label to understand the taste and treatment technique. The International Bottled Water Association has bottled water information. 

People may prefer bottled water since it lacks chlorine and has no chlorine taste. However, bottled water can lie on store shelves for a long period before being sold. You can filter tap water if it accommodates your taste preferences. 
 

Black specks in tap water are often caused by rubber plumbing fittings degrading in contact with tap water chlorine and chloramines. Degraded gaskets and o-rings can gather in toilet tanks and faucets.  

Specks that can be smudged between fingertips indicate degrading rubber. Silicate or manganese is likely if it does not smear between your fingertips. Our Customer Service Department can clean your home's water distribution mains to clear silt or manganese. After flushing the mains, flush your residential lines.  

New or restored structures can have particle issues. Plumbers sometimes disrupt plumbing systems. Flushing new systems can help. 

If your garments or towels smell after laundering, check the washing machine. Wet laundry will show odors from the washing machine. After drying, the laundry smells much better but returns when damp. Washing machine scents can come from two sources:

1. Clothes may smell “sour” after prolonged wetness.  
2. Lint, filth and moisture from the washing machine can cause odor transfer to garments. To reduce odor, consult the owner's manual.  

Water appears colorless in small amounts, but it turns bluer as the sample size increases due to its interaction with light and other basic properties.

Odors like rotten eggs or sulfur suggest bacteria in your drain or water heater. Use bleach to clear the drain. Let the cold water run. Bring a cup of cold water from the sink where you noticed the odor to another room to smell it. If the smell persists, check the water heater. Most manufacturers recommend annual water heater cleansing. Consult your manufacturer's instructions.

Older plumbing might have a metallic aftertaste due to copper and iron corrosion.  
Hot water, poor plumbing, or stagnant water conditions (as when a house is closed for lengthy periods of time) can accelerate plumbing corrosion. Metallic tastes can also emerge when new plumbing or fixtures and metallic materials have not settled. 
 
Prince William Water's suppliers, Fairfax Water and City of Manassas, add a corrosion inhibitor to prevent metals from seeping into drinking water. Run cold water for a few minutes to freshen your home plumbing if your water tastes metallic.

After a hot, dry summer, tap water may smell earthy/musty in the fall. All surface waterways have algae, but summertime algae are numerous. Algae die off and emit two harmless chemicals that smell earthy or musty as water temperatures drop. We can smell tiny amounts of these chemicals.

Prince William Water consistently tests and monitors the water to make sure that it meets or exceeds EPA’s safe drinking water standards. Tap water that meets EPA standards is typically safe. We take pride in maintaining high water quality throughout our distribution system.  

Between April and June, a slight change is made in the water treatment process to facilitate an effective flushing program and maintain water quality. During most of the year, chloramine (ammonia and chlorine) is added to drinking water as the primary disinfectant. In spring, our drinking water providers switch to free chlorine. This temporary change in the water treatment process helps prevent bacteria from becoming overly resistant.  

You may notice a chlorine taste and odor in your drinking water while free chlorine is utilized. If you are especially sensitive to the taste and odor of chlorine, try keeping an open container of drinking water in your refrigerator. This will enable the chlorine to dissipate, thus reducing chlorine taste and odor. 
 

The pink/orange toilet stains are likely Serratia marcescens bacteria. These bacteria are most common in toilet bowls, shower stalls, dishwashers, tiles, sinks and pet water dishes.

Any damp place with phosphorus or fat will develop the bacterium. Serratia can grow in toilets where water stands long enough to evaporate chlorine residual disinfection. Chlorinated water kills Serratia and bleach removes microorganisms from toilets. 

Prince William Water's state-certified Water Quality Laboratory performs or administers state and federal testing to ensure that our water meets or exceeds regulatory standards. In addition to regulated testing, several other analyses check distribution system water quality. 

If chlorine is not removed before using in your aquarium, Prince William Water tap water can harm fish. Prince William Water flushes with free chlorine from April to June and utilizes chloramines, a chlorine-ammonia mixture, the rest of the year. Ask your pet retailer about chlorine and chloramine removal.

Mineral residue on items is from water's natural mineral content, such as calcium.

White particles in ice cubes are harmless minerals.

Hot water from a heater may include substances that should not be consumed. These impurities may include domestic plumbing metals concentrated after heating. Hot water has more contaminants because it absorbs household plumbing materials faster than cold water. 

Tap water can safely be stored for up to six months if stored properly, and the United States Department of Agriculture recommends replacing stored water every six months. Water should be stored away from sunlight, in cool temperatures and away from toxic substances. Visit our 'Prepare for Water Emergencies' page for more information about storing water.

This might happen when the water entering the house is colder than the inside temperature. Cold water contains more oxygen than warm water, so when cold water from the water mains outside warms up in our warm houses, the oxygen must escape. Milky water is caused by air bubbles rising to escape the water.

Both federal and state agencies regulate drinking water. The Environmental Protection Agency (EPA) enforces the 1974 Safe Drinking Water Act (SDWA) revised in 1986 and 1996. For more information on drinking water rules and regulations, please visit our Regulatory Affairs page. 

These whitish specks are possibly hot water heater dip tube pieces. Many 1980s hot water heaters had a defective dip tube that disintegrates with time. The dip tube transports cold water from the hot water heater's top to the bottom for heating. Over time, the dip tube breaks down and white particles enter domestic pipes. If large enough, particles become stuck in sink faucet or showerhead strainers. If they're from the dip tube, these particles won't be in the toilet bowls, tanks, or automatic ice maker because they only affect hot water. Call your hot water heater manufacturer for help with this issue.

Dialysis machines require further treatment of tap water to remove specific substances like aluminum, fluoride and chloramines. Please consult with your healthcare provider for more information. 

Drinking from garden hoses can introduce harmful substances so we do not recommend drinking from your garden hose. Food grade hoses are safer.

Prince William Water is aware of the September 2024 U.S. District Court ruling from California regarding fluoride in drinking water. Prince William Water purchases our drinking water wholesale from Fairfax Water and the City of Manassas, both of which are awaiting guidance from the Environmental Protection Agency and the Virginia Department of Health on this matter.

Currently, both Fairfax Water and the City of Manassas add fluoride to drinking water at or near 0.7 parts per million (ppm), following federal and state public health agency standards, including the Virginia Department of Health (VDH) and the Centers for Disease Control (CDC). Fluoride is added to drinking water to serve a public health goal to decrease the occurrence and severity of tooth decay and reduce the risk of dental fluorosis.  VDH, CDC and Fairfax Water have additional information and data on fluoridation on their websites at the following:

• Virginia Department of Health
• Fairfax Water
• Centers for Disease Control & Prevention

General guidelines for classification of waters are as follows: 0 to 17 mg/L as calcium carbonate is classified as soft; 17.1-60 mg/L as slightly hard; 61 to 120 mg/L as moderately hard; 121 to 180 mg/L as hard; and more than 180 mg/L as very hard.  

Our water is moderately hard in the East and West Systems and hard in Bull Run Mountain/Evergreen. For more information, visit our 'Water Hardness Information' page. 

Customers living in Prince William County receive drinking water from different sources based on their location.

Households in eastern and central Prince William County, such as in Dumfries, Occoquan, Carter’s Grove, Woodbridge, Triangle and Hoadly Road, receive water sourced from the Occoquan Reservoir and treated at Fairfax Water’s Frederick P. Griffith Water Treatment Plant.

Customers in western Prince William County, Greater Manassas and Manassas South receive water that is a blend of water sourced from the Potomac River and treated at Fairfax Water’s James J. Corbalis, Jr. Water Treatment Plant along with water from Lake Manassas treated at City of Manassas’ water treatment plant.

A small cluster of customers in the Bull Run Mountain/Evergreen neighborhoods receive their water from six wells treated with sodium hydroxide to prevent plumbing corrosion. 

No, customers must take precautions to remove or neutralize chloramines and free chlorine in water used in fish tanks and ponds.

Water must be treated to remove free chlorine and chloramines before use in dialysis. We notify all centers in our service area about the conversion to free chlorine each year before switching the disinfectant from chloramines. 

Dialysis patients can safely drink water treated with either free chlorine or chloramines.

Rubber components and materials, which can deteriorate over time, are sometimes used in older home plumbing systems and water heaters. When replacing rubber plumbing components, ask for chloramine-resistant parts, which you can get from your plumber or at hardware stores. Follow manufacturers' recommended use for chloramine-resistant parts.

To remove chlorine smell and taste from tap water, fill a pitcher with water and leave it uncovered on your counter or in your refrigerator. Within a couple of hours, the chlorine will dissipate. 

Every spring, the City of Manassas and Fairfax Water, the drinking water suppliers to Prince William Water, temporarily switch from using chloramines as the main disinfectant in their water treatment process to free chlorine. According to our water suppliers, this short-term change is a best practice for the drinking water industry and makes it easier to implement a flushing program for the distribution system.

Free chlorine is also used to disinfect drinking water, but it is a stronger disinfectant than chloramines.

Chloramines are a disinfectant used in drinking water to remove bacteria and viruses. 

Our Water Quality Report provides up-to-date information about the quality of your water.

For more information, please contact Prince William Water’s Regulatory Affairs Office at (703) 331-4162 or email water_quality@pwwater.org. 
 

Fairfax Water supplies potable water from the Occoquan Reservoir, meeting all regulatory standards for East Prince William County. Prince William Water remains confident in Fairfax Water's quality. Stormwater management and land use decisions rest with Prince William County, supported by regional collaboration to maintain water quality.

To protect public health, the EPA creates national regulations. These drinking water standards are enforced by VDH in Virginia. Prince William Water sends VDH its water quality test findings monthly and annually to ensure the utility fulfills federal and state drinking water regulations. If a water quality violation occurs, Prince William Water must notify VDH and its customers immediately and work with VDH to correct it.

Fairfax Water, which supplies most Prince William Water drinking water, disinfects with ozone and chloramines. Some of our western Prince William clients get drinking water from Manassas, which disinfects using chloramines. In spring, Prince William Water's water providers clean drinking water with free chlorine, a stronger disinfectant, to prevent bacteria from developing resistances.

Free chlorine and chloramines react with organic materials like decaying plant material in water to generate disinfection byproducts (DBPs). EPA and VDH regulate DBPs, Total Trihalomethanes (TTHM) and Haloacetic Acids (HAA5).  

TTHM and HAA5 sample results in Prince William Water's distribution system are regularly below the EPA standard, which Virginia Department of Health enforces.  

Certain cancers have been linked to chronic DBP exposure. The World Health Organization estimates that aquatic microorganisms pose 10,000 to 1 million times the risk of cancer from DBPs. Chloramines produce less DBPs than free chlorine because their chemical nature makes them less reactive to organic materials.  

No. You should only use water from an approved, tested source. Without routinely testing the water there is no way to know if the water is safe to drink.

Many industrial and domestic water users are concerned about the hardness of their water. Hard water requires more soap and synthetic detergents for home laundry and washing, and contributes to scaling in boilers and industrial equipment. Hardness is caused by compounds of calcium and magnesium and by a variety of other metals. Water is an excellent solvent and readily dissolves minerals it comes in contact with. As water moves through soil and rock, it dissolves very small amounts of minerals and holds them in solution. Calcium and magnesium dissolved in water are the two most common minerals that make water "hard." 

The hardness of water is referred to by three types of measurements: grains per gallon, milligrams per liter (mg/L) or parts per million (ppm). The table below is provided as a reference.y compounds of calcium and magnesium and by a variety of other metals. Water is an excellent solvent and readily dissolves minerals it comes in contact with. As water moves through soil and rock, it dissolves very small amounts of minerals and holds them in solution. Calcium and magnesium dissolved in water are the two most common minerals that make water "hard." 

The hardness of water is referred to by three types of measurements: grains per gallon, milligrams per liter (mg/L) or parts per million (ppm). The table below is provided as a reference.

The Environmental Protection Agency (EPA) establishes standards for drinking water which fall into two categories — Primary Standards and Secondary Standards. Primary Standards are based on health considerations and Secondary Standards are based on aesthetics such as taste, odor, color or corrosivity. There is no Primary or Secondary standard for water hardness. In fact, the National Research Council (National Academy of Sciences) states that hard drinking water generally contributes a small amount toward total calcium and magnesium human dietary needs (National Research Council, Drinking Water and Health, Volume 3, National Academy Press, Washington, D.C., 1980) ​