The Eno River is Hillsborough's water source. Water from the river is drawn from three sites located in the Upper Neuse River watershed. The Eno and these three sites are considered surface water — natural water that has not penetrated much below the ground.

Lakes on the Eno River

• Lake Ben Johnston — Hillsborough takes water from this lake to make drinking water. Seven Mile Creek enters the Eno River upstream of this area.
• Lake Orange — The town uses this lake as a secondary source of water from the Eno. The lake is on the east fork of the river outside town limits. It is maintained by Orange County.

West Fork Eno Reservoir

The town owns this reservoir on the west fork of the Eno River in nearby Cedar Grove and uses it as a secondary source for water. It can store about 1.2 billion gallons of water — about two years of supply. 

The reservoir opened in 2000, and a second phase was completed in 2021. It includes an innovative spillway that provides more surface in a compact area for water to spill over. The dam resembles piano keys when in use.

In the 1980s and early 1990s, the Hillsborough community began exploring options for addressing the town’s water shortage due to a history of droughts and water restrictions and a desire to accommodate expected future growth. In 1993, Hillsborough voters approved general obligation bonds to help pay for building the reservoir’s first phase.

The first phase was built with expansion in mind. The reservoir’s 20-year permit allowed for a second phase to be started by 2018. In 2000, the reservoir was made operational earlier than scheduled and before full to help provide immediate drought relief for customers under water restrictions.

Severe Droughts

Hillsborough experienced severe droughts in the 1920s, 1930s, 1950s, 1980s and 2000s. In 1954, schools closed at noon and the town sought federal aid because of drought conditions. That same year, drought conditions forced the town to disconnect the water of any customer found wasting it. In 1988, mandatory water restrictions were put in place.

By the early 1990s, the town completed an interconnected pipeline with the City of Durham to allow regular purchases from Durham’s water system to withstand periods of droughts and water restrictions. The town could only purchase water between 10 p.m. and 6 a.m. due to demands on Durham’s system.

Benefits

Phase 1 of the reservoir has:

• Helped the town withstand several severe droughts in the 2000s. At one point, larger surrounding systems were near or below 50 days of remaining water, but Hillsborough still had enough water for 200 days.
• Allowed Hillsborough to accommodate new development. Many residents and businesses joining Hillsborough after 2000 would not be here today without the reservoir.

The Phase 2 expansion of the reservoir:

• Is a long-term investment in Hillsborough’s water supply.
• Raised the reservoir about 10 feet, doubling its volume and providing a maximum yield of 6 million gallons of water per day.

Recreation is not allowed at the West Fork Eno Reservoir or the surrounding town-owned property. This includes boating, hunting and fishing. 

Required Conservation

Federal and state permits require a conservation easement to:

• Protect the town’s drinking water source.
• Reduce the effects of the reservoir on others.

To provide a 100-foot buffer around the reservoir, the town must keep the land in a natural state with no development, recreation or access other than to maintain the reservoir.

Risks

The town does not have the resources to oversee public activities at the reservoir and cannot assume the risk or liability of allowing recreational activities.

Recreation also could introduce invasive animals and plants. The town already funds treatment to remove a weed native to South Asia that can damage utility equipment and the environment. See the section on annual treatment for an invasive plant on this page.

The state annually treats 16 miles of the Eno River with the herbicide fluridone to reduce hydrilla, an invasive aquatic plant. Applications typically start in mid-May and continue through August.

• The section of the river treated is below the Ben Johnston Lake dam in Orange County to Roxboro Road and U.S. 501 in Durham County.
• The herbicide is applied in a concentration that is safe for humans, fish and wildlife and well below limits set by the Environmental Protection Agency.
• Property owners next to the treated section of river should use caution in using river water for irrigation during this time. 

About Hydrilla

Hydrilla is native to South Asia and grows rapidly, creating thick mats on the surfaces of lakes, rivers and other waterways. The weed:

• Negatively affects the health of fish and wildlife in the area.
• Can clog intakes for supplying drinking water and irrigation.
• Can harbor mosquitoes.
• Can interfere with recreation on waterways.

The plant was discovered in the Eno River watershed in the early 1990s in Lake Orange, which is upstream of Hillsborough and one of the town's water sources. In 2009, biologists confirmed hydrilla in the West Fork Eno Reservoir. The town-owned reservoir is stocked with triploid grass carp to manage the invasive plant.

More Information

The North Carolina Division of Water Resources manages the annual treatment. Hillsborough helps fund it.

For more information, contact Stormwater and Environmental Services Manager Terry Hackett by email or phone at 919-296-9621.

The town's water treatment must meet high standards set by the town, state and federal governments. Hillsborough routinely tests for more than 150 substances in the town's drinking water and meets or exceeds the standards. See the annual Water Quality Report.

Water Plant Testing

Staff monitor and evaluate water 24 hours a day. The plant has:

• A state-certified laboratory to test for bacteria daily.  
• Two lab-certified operators who test raw and finished water at the plant every two hours — more than required by the state.

Water System Testing

Staff also test various points in the water system. The water system includes the pipes, pumps and tanks needed to transport and store water. Tests occur:

• Weekly — For bacteria at five of the farthest points in the town's water lines.
• Monthly — For bacteria at 15 areas.
• Quarterly — For disinfection byproducts. These are substances created by the process to clean water.
• Annually — For inorganic materials, pesticides, synthetic organic chemicals, nitrates, volatile organic compounds and secondary contaminants.
• Every five years — For unregulated contaminants that the Environmental Protection Agency lists for testing.

The Hillsborough Water Treatment Plant is the processing plant for your water. The plant takes raw water from the Eno River. It then adds ingredients and applies processes to the water to make it usable. The plant focuses on:

• First — Cleanliness and compliance with standards.
• Second — Taste, odor and appearance.

Water Treatment

Converting raw water into drinking water includes injecting chemicals at multiple points to help remove organic material, disinfect the water and ensure longer freshness before releasing it for use by the community.

The chemical process starts before the raw water reaches the Water Treatment Plant. Water released from the town's reservoir travels to Lake Ben Johnston, where the town removes water for use. At this intake location, a chemical is added to help particles in the water combine for easier removal. 

At the plant, more chemicals are added for the same reason and to adjust the water's color, acidity and alkalinity. 

Filtering Out Materials

The water then goes through several filtration, aeration and clarification stages. In these stages, the water remains in large basins while being mixed at slower and slower speeds. This allows the combined large materials to drop to the bottom of the basins.

Finally, the clear water moves through a fine filtration system to remove remaining particles. At this stage, the water’s turbidity is measured and filtration adjustments are made to remove any cloudiness from the water caused by large amounts of particles that are otherwise invisible to the eye.

Adjusting Treatment

The water is then disinfected and final adjustments to acidity and alkalinity are made before the water is pumped through pipes to homes and businesses.

Throughout the treatment process, employees test the water for more than 150 contaminants, making adjustments to the treatment as needed.

See:

• From River to Faucet: Hillsborough's Water Treatment Process video

The Water Treatment Plant employees are highly certified. They continually operate and maintain the plant 24 hours a day to ensure compliance with state and federal permits and regulations.

The plant can treat up to 3 million gallons of drinking water per day. 

Awards

In previous years, the Water Treatment Plant and its staff won an award for Outstanding Operator of the Year from the N.C. Waterworks Operators Association.

Tours

See what it takes to prepare water taken from the Eno River for drinking. 

• Public tours are offered at 1 p.m. on the second Friday of the month in March and September.
• Private tours can be scheduled separately for special groups.
• All tours are open to a maximum of 10 people with participants at least 10 years old.
• All tours require complete a request form.

For one month each year, the town is required to disinfect drinking water with chlorine. The state requires this annual change in utilities that normally use chloramines, a compound of chlorine and ammonia. Chlorine is a more intense disinfectant, and the annual change helps ensure a high level of disinfection in water mains. 

Other utilities in the region conduct the disinfection at the same time. This includes Hillsborough’s interconnected neighboring utilities, Orange Water and Sewer Authority and the City of Durham. 

Effects on Customers

During the annual disinfection, some customers may notice a chlorine taste or odor in Hillsborough’s drinking water. Your water remains safe to drink.

During the annual disinfection, some customers may notice a chlorine taste or odor in Hillsborough’s drinking water. Your water remains safe to drink.

To remove chlorine taste and odor from water, you can:

• Add a few lemon slices to a pitcher of water. The lemon’s ascorbic acid will neutralize the chlorine.
• Let water sit in an open container in the refrigerator or on a counter for a day or so. A wide or shallow container will allow more contact between the air and water.
• Filter water with activated carbon. Water pitchers with such filters are sold locally.
• Boil water for 15 minutes to evaporate the chlorine.

If you use Hillsborough water for special purposes or for processes involving careful control of water characteristics, the town encourages you to seek advice from an appropriate technical source — such as a filter vendor or service company — about whether and how to make adjustments to your use of Hillsborough water during the month of chlorine disinfection.

During the annual disinfection, staff release water from fire hydrants to ensure chlorine flows through the entire system. They also perform maintenance on hydrants.

The annual flushing helps remove sediment and other minerals that may have settled in the water system. This flushing can cause temporary cloudiness or discoloration of water and could discolor light-colored fabric. If discoloration or air bubbles appear in the water, customers should run cold water in a bathtub for a few minutes until the water and air bubbles clear. If the water does not clear within five minutes, contact the Water Treatment Plant at 919-732-3621.

During flushing or hydrant maintenance:

• Town personnel may be required to trim plantings or remove other items to ensure that adequate access to the hydrants exists for emergencies and maintenance. 
• Community members may be asked to relocate plants and other items in street rights-of-way where necessary to provide a clear, 3-foot-wide area around a hydrant. 

The responsibility for repairs of water lines depends on whether the water line is on the utility or the property owner's side of the service connection.

Responsibilities

• The town owns and maintains the water main. The supply system's main line typically is located under roadways. The town also maintains water service connections in public rights of ways or easements. It will make repairs to the line in that area.

• Property owners are responsible for the water service line between the property and public right of way or easement.

Water Meter

A property's water meter typically indicates the ownership line. The meter is placed on the line between the property's edge and the public right of way or easement. If a water meter is not located in the public right of way or easement, the town will provide water service maintenance to the meter and can relocate the meter or require relocation during redevelopment.

The Water Distribution Division repairs water line breaks and maintains:

• 153 miles of water lines
• 3 water boosting pump stations
• 5 water tanks

The division includes a backflow prevention program to prevent contaminants from entering the water supply.

Awards

In past years, the division has won Outstanding Water Distribution Operator of the Year from the N.C. American Water Works Association-Water Environment Association.

Black residue around utility fixtures generally does not indicate a problem with water quality. It is likely due to one of the following:

• Bacteria feeding on oxidized iron and manganese in water.
• A reaction between ammonia that the town uses for disinfection and rubber in faucet rings or toilet flaps.

Iron and manganese are naturally occurring minerals and are in most water across the United States. The bacteria that feed on iron and manganese are non-health threatening. As they feed on the minerals, they form red-brown or black-brown residue that can clog water systems and cause a foul odor.

Hillsborough and neighboring utilities use chloramines — a compound of chlorine and ammonia — to disinfect and preserve water.

Removal

To remove the iron and manganese bacteria, use equal parts of white vinegar, peroxide and water to clean any residue seen. This solution can be used periodically as a preventative measure on utility fixtures.

To resolve the issue of a reaction between ammonia and rubber, the rubber materials in faucets and toilets can be replaced with materials that can withstand ammonia. Check labels on replacement products.

To request testing or to make utilities crews aware of the issue and location, call the Hillsborough Water Treatment Plant at 919-732-3621. Crews can take a water sample from the home to determine the cause and discuss solutions.

A pink to reddish film or residue on bathroom and kitchen surfaces is likely the result of airborne bacteria in the home that produce a pinkish or dark gray film on routinely moist surfaces, such as toilet bowls, showerheads, sink drains and tiles.

The bacterium is likely Serratia marcescens, which is found naturally in soil, food and animals. It produces a red pigment and thrives on moisture, dust and phosphates, such as soap and shampoo residue. The bacteria have been tied to urinary tract infections, wound infections and respiratory problems in some people.

Removal

To prevent the pink residue:

• Keep bathtubs and sinks wiped down and dry.
• Clean surfaces with a solution that contains chlorine.
• Periodically disinfect toilets with chlorine bleach.

Note that abrasive cleaners may scratch fixtures and allow increased growth of bacteria.

Before resuming use of a building or during periods of underutilized use, remove stale and potentially unhealthy water in your building’s water system by flushing the water system and all water devices.

For more information, contact the Water Treatment Plant.

Background

When buildings are vacant or operating at significantly reduced capacity for more than a few days, water sits in pipes and devices instead of flowing. The chlorine and ammonia that the Hillsborough Water Treatment Plant adds to disinfect water disappears over time. Without proper levels of disinfectant, disease-causing microorganisms can begin to grow. Corrosion control also can be affected.

Flushing Water Systems and Devices

Flushing in stages is best. Begin at the main service line and include all the plumbing, storage tanks, fixtures, fire suppression systems, and equipment such as water fountains and ice machines. 

• The first flush pulls out stale water.
• Follow-up flushes ensure fresh water with disinfectant is drawn fully through the building.

For larger buildings, a single flush isn’t enough to reestablish good water quality. The longer service is interrupted, the more flushing is needed.

Depending on the complexity of a building’s water system, facility managers should develop a comprehensive water management program for this process, but it should not replace a facility-specific Water Management Plan.

Flushing Steps to Consider

In addition to the following steps, consider capturing and reusing flushed water for outdoor watering or cleaning purposes.

• Flush all interior and exterior faucets (remove faucet aerators, if possible) for 10 to 30 minutes.

• Open all outlets at once to flush the service line and then open them again, individually, starting near where the water enters the building.

• Flush cold water first. Then flush hot water until it reaches its maximum temperature.

• Follow manufacturer recommendations to flush water fountains, hot water tanks, hot water recirculating loops, ice makers, dishwashers, humidifiers, and cooling towers.

For information on the quality of your water, see the annual Water Quality Report.

If you have concerns about your water quality or would like more information, contact the Water Treatment Plant at 919-732-3621. The town will test water for its customers at no charge. See the section on whole house filters on this page regarding testing.

Private Testing

• Certified Laboratories — For private water testing, find a certified lab on the North Carolina Department of Environmental Quality website by searching for drinking water laboratories.

• Testing Kits — If you receive any water testing kits by mail, they are from private companies unaffiliated with the town.

Whole house water filter systems are devices that customers can buy privately to treat their water.

Issues to Keep in Mind

Bacteria — Most water filters must be changed every 30 days to prevent bacteria from growing, and many water filters eliminate chlorine. The town adds chlorine to its drinking water for disinfection. Without adequate disinfection, bacteria will start to grow.

Poor Water Quality — Use of a filter that eliminates chlorine will cause free ammonia to be left in the filtered water. This could cause chemical substances in the water to change, resulting in poor water quality. Specifically, ammonium salts could change to nitrites and then nitrates in a process called nitrification. Nitrate contamination can be unhealthy, particularly for infants. Hillsborough adds ammonia to water as part of its disinfection process. The ammonia bonds with chlorine to produce chloramines to cleanse water.

Water Testing — If a water quality issue occurs in a home with a whole house filter system, the town cannot test the water. Whole house filters provide secondary treatment to water. Test results at homes with these filters would not provide data on the water that Hillsborough delivers.