MVD’s water quality and sampling requirements are regulated by the New Hampshire Department of Environmental Services (NHDES) as well as the United States Environmental Protection Agency (EPA). In order to ensure that tap water is safe to drink, the EPA prescribes regulations that limit the quantity of certain contaminants in water provided by public water systems. To comply with the required regulations, MVD tests for various contaminants, including inorganic contaminants (salts, metals), organic chemical contaminants (synthetic and volatile chemicals), and radioactive contaminants, as well as some additional unregulated contaminants/chemicals. In addition to routine sampling, MVD also complies with the EPA's Unregulated Contaminant Monitoring Rule (UCMR) Program, which requires public water systems to test for priority contaminants that may be present in drinking water but do not yet have established health-based standards. Water analyses and treatments are performed as required and directed by the EPA’s Safe Drinking Water Act (SDWA) and the NHDES Drinking Water and Groundwater Bureau (DWGB).
All water tests are performed by an independent laboratory that is accredited in accordance with the National Environmental Laboratory Accreditation Program (NELAP) & the New Hampshire Environmental Laboratory Accreditation Program (NHELAP). All testing is reported to and monitored by the NHDES. Results from these tests are provided on MVD’s Annual Water Quality Report. 

Click HERE to view additional information about MVD's Water Quality, including the most recent Water Quality Report.

Click HERE to view PFAS information

MVD’s water quality and sampling requirements are regulated by the New Hampshire Department of Environmental Services (NHDES) as well as the United States Environmental Protection Agency (EPA). In order to ensure that tap water is safe to drink, the EPA prescribes regulations that limit the quantity of certain contaminants in water provided by public water systems. To comply with the required regulations, MVD tests for various contaminants, including inorganic contaminants (salts, metals), organic chemical contaminants (synthetic and volatile chemicals), and radioactive contaminants, as well as some additional unregulated contaminants/chemicals. In addition to routine sampling, MVD also complies with the EPA's Unregulated Contaminant Monitoring Rule (UCMR) Program, which requires public water systems to test for priority contaminants that may be present in drinking water but do not yet have established health-based standards. Water analyses and treatments are performed as required and directed by the EPA’s Safe Drinking Water Act (SDWA) and the NHDES Drinking Water and Groundwater Bureau (DWGB).
All water tests are performed by an independent laboratory that is accredited in accordance with the National Environmental Laboratory Accreditation Program (NELAP) & the New Hampshire Environmental Laboratory Accreditation Program (NHELAP). All testing is reported to and monitored by the NHDES. Results from these tests are provided on MVD’s Annual Water Quality Report. 

Click HERE to view additional information about MVD's Water Quality, including the most recent Water Quality Report.

MVD’s water quality and sampling requirements are regulated by the New Hampshire Department of Environmental Services (NHDES) as well as the United States Environmental Protection Agency (EPA). In order to ensure that tap water is safe to drink, the EPA prescribes regulations that limit the quantity of certain contaminants in water provided by public water systems. To comply with the required regulations, MVD tests for various contaminants, including inorganic contaminants (salts, metals), organic chemical contaminants (synthetic and volatile chemicals), and radioactive contaminants, as well as some additional unregulated contaminants/chemicals. In addition to routine sampling, MVD also complies with the EPA's Unregulated Contaminant Monitoring Rule (UCMR) Program, which requires public water systems to test for priority contaminants that may be present in drinking water but do not yet have established health-based standards. Water analyses and treatments are performed as required and directed by the EPA’s Safe Drinking Water Act (SDWA) and the NHDES Drinking Water and Groundwater Bureau (DWGB).
All water tests are performed by an independent laboratory that is accredited in accordance with the National Environmental Laboratory Accreditation Program (NELAP) & the New Hampshire Environmental Laboratory Accreditation Program (NHELAP). All testing is reported to and monitored by the NHDES. Results from these tests are provided on MVD’s Annual Water Quality Report. Based on these strict requirements and regulations, MVD does not provide testing at individual locations; property owners/residents may have water testing performed at their own expense if they choose. 

Should you have any questions, please contact MVD’s Business Manager/Water Quality Specialist, Jill Lavoie, at 603-424-9241 x: 103 or by email to jlavoie@mvdwaternh.gov.

Click HERE to view additional information about MVD's Water Quality, including the most recent Water Quality Report.

MVD has 6 Groundwater Wells, 3 Water Storage Tanks, an Iron & Manganese Treatment Facility, three Booster Stations, and three PFAS Treatment Facilities.

Once pumped from the wells, water treatment occurs on-site at each pumping station. Water from all online wells is chlorinated for disinfection and treated with granular activated carbon (GAC); additionally, wells 7 and 8 are treated for naturally occurring Iron and Manganese. Corrosion control treatment prevents both pipe deterioration and the presence of metals in drinking water. MVD's Corrosion Control Treatment Program involves monitoring and adjusting water chemistry parameters to minimize corrosivity; this is achieved by regulating pH levels and utilizing phosphate as a corrosion inhibitor. Once water treatment has been completed, water is then pumped to one of the three water storage tanks. When needed, water is sent from the tanks into the distribution system through a network of over 175 miles of water mains. All of MVD’s water that is sent to the distribution system is compliant with all NHDES and EPA regulations.

Click HERE to view additional information about MVD's Water Quality, including the most recent Water Quality Report.

MVD does NOT add fluoride.

MVD’s water quality and sampling requirements are regulated by the New Hampshire Department of Environmental Services (NHDES) as well as the United States Environmental Protection Agency (EPA). In order to ensure that tap water is safe to drink, the EPA prescribes regulations that limit the quantity of certain contaminants in water provided by public water systems. 

Click HERE to view additional information about MVD's Water Quality, including the most recent Water Quality Report.

100% of MVD’s water comes from groundwater. Groundwater is precipitation that has soaked through the ground’s surface and is stored where there are open spaces between rocks and soil. This water is pumped from wells located in various parts of Merrimack and Hollis. Water from each well is filtered and distributed through a network of water mains to residential, municipal, commercial, and industrial locations. The water from MVD’s wells is distributed through MVD’s water mains, which are an interconnected, looped system. Depending on the situation, wells may be on or off at any given point in time. The well source for the water provided may vary based on which wells are on and producing water.

• Cloudy, White, or Milky – Caused by air, which is harmless. As the water sits, the air will dissipate, and the water will clear. 

• Brown/Orange/Rusty/"Dirty" – Typically caused by sediment, such as naturally occurring iron, that accumulates in the water mains located in the street and in the service lines connected to the water. While discolored “brown” water is not aesthetically pleasing, it is not unsafe*. Sediment normally settles in the mains and service lines; however, it can be “stirred up,” causing it to dislodge and subsequently discolor the water.
  • Discolored water can be easily resolved by flushing the water service line to the property. Flushing allows a larger than normal quantity of water to flow through the service line, which helps clear out the sediment. Please note, discoloration can return after the water has sat in the lines for a period of time, such as overnight or during the day if it’s not being used – this is to be expected. When the water is not used for a longer period of time, the sediment settles; when water is turned on, it is agitated and the discoloration returns. If this happens, you may repeat the flushing process. If your water is discolored, we recommend avoiding the use of hot water until the cold water is clear. If you are noticing discoloration in the hot water, the water heater may need to be flushed – refer to the manufacturer’s manual for additional information or contact a licensed plumber.

• Sandy/Gritty – What appears as “sand” is actually a derivative of calcium carbonate, a naturally occurring compound. “Sand” occurs due to issues with hot water heaters, such as the temperature being set too high – refer to the manufacturer’s manual for additional information or contact a licensed plumber.

The most frequent causes of the above types of issues are from water outages, pressure fluctuations, high demand/high usage (ex: water main flushing/excessive seasonal usage), water main/service line breaks, substantial water leaks, plumbing disturbances (ex: repairs/issues or damages/water leaks) 

*Some people may be more vulnerable to contaminants in drinking water than the general population. These individuals should consult with and seek advice from their health care providers.

• Black Particles –This issue is likely coming from the plumbing. The three most common sources of the particles are old pipes deteriorating & eroding, corroding water heaters, or parts such as gaskets/washers breaking down.
• Pink Rings in Toilets/Sinks – This is not a water quality issue. This is likely the result of an airborne bacteria, known as Serratia Marcescens, that thrives in moist areas. The best way to eliminate the problem is to clean with a bleach-based cleaner.

Chlorine is a highly efficient disinfectant. MVD uses chlorine to neutralize bacteria, parasites, viruses, and assorted harmful microorganisms before it enters the distribution system and is used by customers. The EPA mandates that a certain level of chlorine be present in public water supplies, which is known as a “residual.”  The maximum residual is 4 mg/l. MVD’s levels are typically lower than 1 mg/l which is well below the maximum, and therefore the presence of chlorine is typically unnoticed. The strength of chlorine scent/taste can depend on the distance of your property to the treatment source (the further away the property is, the more the chlorine dissipates) as well as the time of year. For example, chlorine dissipates more quickly in warm weather, so treatment levels may be increased in order to compensate for the dissipation. Additionally, the strength of the taste/smell is different for each person – some people are more sensitive to chlorinated water than others. While a chlorine smell is certainly unpleasant, over time, chlorinated water will naturally lose its smell, but if preferred, using a filtration system will eliminate the odor immediately. 

Sulfur bacteria are naturally present in groundwater. The smell of sulfur is produced when sulfur bacteria break down organic matter and release hydrogen sulfide gas, often leaving an aroma of rotten eggs. Sulfur bacteria dwell in oxygen-deficient environments such as plumbing systems and feed on decaying organic matter, creating hydrogen sulfide gas that gets trapped in water sources. If you smell sulfur only when you use the hot tap, your water heater may be the culprit. Reactions caused by the magnesium rod and aluminum in your water heater produce hydrogen sulfide gas, yielding a stronger sulfur scent when you use the hot water – refer to the manufacturer’s manual for additional information or contact a licensed plumber.

Most pressure issues, whether low or high pressure, are caused by an internal/plumbing issue. 

• Is MVD performing repairs, maintenance, or flushing in the area?
  If we are, then that is probably the cause of the issue. Once the work has been completed, water should be restored to normal pressure. Click HERE to view the FLUSHING & MAINTENANCE SCHEDULE.

• Is there a water filtration device?
  If yes, check the device to ensure it is working properly and verify the filter does not need to be cleaned/replaced.
• Is the issue affecting the entire location - ALL faucets, ALL fixtures, ALL appliances?
  If it’s not affecting the entire location, then it is an internal issue.

• Is the issue affecting both the hot & cold water?
  If it is affecting the hot water only, it is an internal issue. 

• Is the issue occurring at a specific time or randomly?
  • If the issue is at a specific time, it could be due to high demand at your location or in the area. For example, if it’s occurring when your irrigation or lawn watering system is running, it is an internal issue.
  • If it seems to happen at/around a certain time of day, it is likely due to high demand. If it seems to occur at random, it could be an MVD-related issue.

• Has there been any recent plumbing work?
  If so, it is likely related and not an MVD issue.

• Have any valves been turned on or off recently?
  If so, it is likely related and not an MVD issue.

If none of these situations are applicable and you are still experiencing low pressure, please contact us.

• Broken Pressure Reducing Valve (PRV)
  A PRV controls the water pressure entering the location. These devices typically begin to fail after about 7-10 years.

• Failed Expansion Tank:
  A thermal expansion tank absorbs excess water volume & pressure that is created when water is heated inside a closed plumbing system. If the expansion tank is broken/defective, it can cause pressure spikes.