The value of our water systems, contaminants, more information and a glossary of water terms.

Keeping Delaware’s faucets running – and running clean – is a big task.

The state’s groundwater-based systems are organized around wells, with associated pump stations, treatment units and storage tanks. Treatment typically includes disinfection and fluoridation, but depending on source water conditions, may involve more complex filtration.

The pipes carrying the water from treatment plant to taps vary by age and material, said Ed Hallock of the Office of Drinking Water.

“We’ve got everything from the city of Wilmington, [whose system] is near 100 years old, to new housing developments in the beach area that were built last year, so we have a large variety of piping systems,” he said.



      ♦ 22.4 percent of residents have individual wells

      ♦ 77.6 percent served by public water

      ♦ 485 public water systems (214 community, 84 TN, 187 T)

      ♦ 482 use groundwater

      ♦ 3 draw from surface water

      ♦ 726,107 residents served by public water systems (241,736 surface; 484,371 groundwater)

      ♦ $4 billion value of state’s total water infrastructure assets

     SOURCE: ODW Annual Compliance Report 2014

  ♦  Glossary  ♦  Online resources  ♦  Nitrates, lead and bacteria  ♦  

A major focus for community water systems right now is updating water mains, he said.

“We’ve gotten the last of the wooden mains out of all the water systems, so most are going to be cast iron, cement asbestos, PVC piping – there’s a lot of that especially south of the canal,” he said.

But whatever the need, each individual water system determines their own priorities, he said.

“All systems should have a capital improvement project to identify their needs over the next 10, 20 years, to maintain good water quality, and a lot of that is replacing old water mains, depending on what their material is – they have different lifespans,” he said.

According to a February 2015 needs assessment by Water Infrastructure Advisory Council – which studies, plans and develops drinking water and wastewater projects and policies – the majority of the state’s public community water infrastructure dates to 1960 or earlier. This means that they are at – or approaching the end of – their useful lives. The report cautions that assets can and do fail earlier than predicted by this “useful life” assessment.

The WIAC estimates the replacement value of Delaware’s water assets at $4 billion, with a majority requiring replacement over the next 50 years. According to their needs report, this equates to an investment of $1.2 billion over the next 20 years.

To help, the WIAC administers a Drinking Water State Revolving Fund, which provides loans and grants for eligible water systems to help replace and update outdated infrastructure. The fund is capitalized by annual federal grants and matching state funds; the agency expects to have $34.9 million available for disbursements in FY2016.

The public water systems of Dover, Milford, Georgetown, Middletown and Smyrna are all borrowers.


Top contaminants

Both the ODW’s Ed Hallock and a needs assessment by the Water Infrastructure Advisory Council point to nitrates and coliform bacteria as Delaware’s major contaminant threats.

NITRATES: In the 2014 Annual Compliance Report, nitrates were the most common contaminants cited, with 11 violations from eight systems. In excess, they can be dangerous, particularly for infants and pregnant women. Common in rural areas, they’re often an agricultural byproduct. Hallock said nitrates are a frequent contaminant in lower Delaware and are monitored aggressively.

“We monitor that above and beyond what the EPA requires,” he said. “We do monthly instead of quarterly to keep a closer eye on that.”

COLIFORM: Bacteria was the second most cited contaminant on the ACR report, with 35 systems reporting 46 violations – five of which were acute, indicating the presence of E. coli. Not all coliform violations are a health risk, but indicate bacterial presence and could mean a future issue.

Hallock said bacterial contamination usually happens when a system component is damaged or a pipe broken.

When a system violates bacteria standards, a boil water notice is required, and with the presence of E. coli, this has to be within 24 hours of being notified of violation. Corrective action typically involves disinfecting the well and checking chlorination equipment.

LEAD: Flint brought national attention to lead contamination in drinking water; fortunately for Delawareans, the risk here is much lower. Lead and copper levels only saw one action level exceedence in 2014, according to the ACR report, and 15 monitoring violations.

Hallock said Flint’s high lead levels came after the city switched water sources without introducing corrosion control chemicals, allowing lead from the pipes to leach into the water. Delaware has far fewer lead lines, and the main source of exposure is old lead-based paint, not plumbing.

For more on lead, see our Q&A with Ed Hallock.


Glossary: Geology

Aquifer- a porous underground formation or group of formations in rocks and soils able to store and transmit useful quantities of water.

Confined aquifer - aquifers sandwiched between impermeable rocks or soil that prevents water from seeping into from above. Zones that restrict the flow of ground water are called aquitards; those that completely prevent the flow of water are called aquiludes.

Recharge area - the land area through or over which rainwater or other surface water soaks through the earth to replenish an aquifer. Also called a watershed.

Unconfined aquifer - aquifers into which water can seep from the ground directly above. It is recharged by rain or snow falling directly onto the ground.

Water table - the upper level of a saturated zone where the water level varies depending on the geography and amount of rain or snow melt present over a season.


Glossary: Water testing

Violation: Failure to meet any state or federal drinking water regulation.

M/R violation: A monitoring or reporting violation; the operator failed to collect proper samples or conduct needed followup. A routine tap violation is one example of this.

Total Coliform Rule (TCR): Total coliform rule – indicates a bacteria violation. Not necessarily a health risk; only indicates presence of bacteria.

Action level: The concentration of a contaminant which, if exceeded, triggers treatment or other requirements which a water system must follow. Not all action levels mean a violation has occurred; a lead or copper exceedance, for example, isn’t a violation, but triggers additional monitoring.

Maximum Contaminant Level (MCL): The highest amount of a contaminant that the EPA allows in drinking water, defined in mg/L.

mg/L: Milligrams per liter, or parts per million – used to measure the amount of a contaminant in a water source.

Return to compliance date: Violations with “Return to compliance date” marked “n/a” indicate systems that had not returned to compliance by the end of that calendar year.

Community (C) system: Serves at least 15 service connections used by year-round residents or regularly serves 25 year-round residents.

Noncommunity (N) system: Serves at least the same 25 non-residential individuals during 6 months of the year.

Transient Noncommunity (TN) system: Regularly serves at least 25 non-residential individuals (transient) during 60 or more days per year.



State of Delaware Office of Drinking Water provides detailed information on drinking water and public notices about violations of drinking water standards;

United States Environmental Protection Agency National Service Center for Environmental Publications; free resource for searching, retrieving, downloading ordering technical, scientifica and educational material from the EPA, some predating 1976;

Delaware Geological Survey, an agency of the University of Delaware focusing on water resources, agriculture, environmental protection and energy and mineral resources;