Lead service line glossary
Plain-English definitions of the terms in utility letters, inventory maps and the federal lead rules.
90th-percentile lead levelAction levelCorrosion control treatmentCurb stopCustomer side (private side)Drinking Water State Revolving Fund (DWSRF)First-draw sampleFlushingFull replacementGalvanized requiring replacement (GRR)Gooseneck (pigtail)Lead and Copper Rule (LCR)Lead and Copper Rule Improvements (LCRI)Lead and Copper Rule Revisions (LCRR)Lead service line (LSL)Lead status unknownNSF/ANSI 53NSF/ANSI 61Open-trench replacementPartial replacementParts per billion (ppb)Service lineService line inventoryTap cardTrenchless replacementUtility side (public side)
- 90th-percentile lead level
- The value that 90% of a water system's tap samples from high-risk homes are at or below. It is compared with the action level. Learn more
- Action level
- The lead concentration that triggers extra steps by a water system when more than 10% of tap samples exceed it. It is 15 parts per billion now and drops to 10 ppb under the Lead and Copper Rule Improvements in November 2027. It is a trigger for action, not a safe level. Learn more
- Corrosion control treatment
- Chemicals a utility adds to the water, such as orthophosphate or pH adjustment, to form a coating inside pipes and keep lead from dissolving into the water.
- Curb stop
- A shut-off valve on the service line, usually near the curb or property line, reached through a small metal box in the ground. It often marks where the utility side ends and the owner side begins. Learn more
- Customer side (private side)
- The part of the service line from the curb stop or property line into the house. In most cities the property owner owns it and historically paid to replace it. Learn more
- Drinking Water State Revolving Fund (DWSRF)
- A loan fund in every state, seeded by EPA, that lends money to water systems for projects including lead line replacement. Part of the money can be given as grants or forgivable loans. Learn more
- First-draw sample
- The first liter of water from a tap after it has sat unused for at least six hours. It is used to measure the lead that collects while water sits in the pipes. Learn more
- Flushing
- Running the cold tap, showering or doing laundry to clear water that sat in the pipes before drinking it. It lowers but does not remove lead risk. Learn more
- Full replacement
- Replacing the entire lead or galvanized service line, both the utility side and the customer side, in one project. Federal rules now require full replacement. Learn more
- Galvanized requiring replacement (GRR)
- A galvanized steel service line that is or ever was downstream of a lead pipe or lead connector, or whose history is unknown. It must be replaced like a lead line. Learn more
- Gooseneck (pigtail)
- A short, flexible connector, usually one to two feet long, joining the water main to the service line. Many older ones are lead. Learn more
- Lead and Copper Rule (LCR)
- The 1991 EPA rule that set the lead action level and required corrosion control and tap sampling. Learn more
- Lead and Copper Rule Improvements (LCRI)
- The 2024 EPA rule that requires most water systems to replace all lead and GRR service lines within 10 years of November 1, 2027, lowers the action level to 10 ppb and largely bans partial replacements. Learn more
- Lead and Copper Rule Revisions (LCRR)
- The 2021 update that required every water system to inventory its service lines by October 16, 2024 and notify customers with lead, galvanized or unknown lines. Learn more
- Lead service line (LSL)
- A water service line made in whole or in part of lead, on either side of the property line. Learn more
- Lead status unknown
- An inventory category for service lines whose material the utility cannot confirm from records. It does not mean the line is safe. Learn more
- NSF/ANSI 53
- The certification standard for filters that reduce health-related contaminants. Look for a filter certified to NSF/ANSI 53 specifically for lead reduction. Learn more
- NSF/ANSI 61
- The certification standard for pipes, fittings and other parts that touch drinking water, used for new service line materials. Learn more
- Open-trench replacement
- Replacing a service line by digging a continuous trench from the street to the house. It is more disruptive than trenchless methods. Learn more
- Partial replacement
- Replacing only one side of a lead service line and leaving lead on the other. It can raise lead levels for a time and is now largely prohibited. Learn more
- Parts per billion (ppb)
- The unit for lead in water. One ppb is one microgram of lead per liter of water.
- Service line
- The pipe that carries water from the water main under the street into a building. Learn more
- Service line inventory
- A utility's list of every service line in its system and its material, required by federal rules and usually published as an address lookup map. Learn more
- Tap card
- A utility record created when a service line was connected to the main, often listing the pipe material and date. Missing tap cards are a common reason for "unknown" status.
- Trenchless replacement
- Replacing a service line by pulling or boring the new pipe from small pits at each end, without digging the whole yard. Learn more
- Utility side (public side)
- The part of the service line from the water main to the curb stop or property line, usually owned by the utility. Learn more