DC Water’s Lead and Copper Rule compliance sampling results: 2021-2023
December 5, 2024
The table below breaks down the lead-in-water monitoring results from the six sampling rounds that Washington DC’s water utility conducted in 2021-2023.
Under EPA’s 1991 Lead and Copper Rule (LCR):
Only 1st-draw samples count for regulatory compliance purposes (these samples tend to capture lead from in-home plumbing),* and
The 90th-percentile value of the results must not exceed the rule’s “lead action level” of 15 parts per billion (ppb) lead.** If it does, water utilities are required to implement remediation measures, such as source water treatment, corrosion control treatment, lead service line replacement, and public education.
Row 2 shows that DC Water meets the LCR’s 15 ppb lead action level comfortably. And that’s good!
Yet every semester (i.e., six-month period) between 70% and 81% of 1st-draw samples are found with detectable levels of lead (Row 3). Some of these levels are high (e.g., 28.3 ppb, 35.8 ppb) and some, exceedingly high (e.g., 111 ppb, 360 ppb). Remember, there is no safe level of lead in water. What these measurements show is that high and exceedingly high lead levels can originate not only from lead service lines (which are made of 100% pure lead and are typically the greatest source of lead from plumbing) but from in-home plumbing as well (see semesters Jan-Jun 2021, 2022, 2023, where 1st-draw lead is significantly higher than 2nd-draw lead).
This means that residents in homes with no lead service line have reason to be concerned about lead in their water.
Similarly, every semester between 65% and 77% of 2nd-draw (or “lead service line”) samples are found with detectable levels of lead (Row 6). Due to a weakness in DC Water’s sampling protocol,*** we suspect that these measurements are underestimations of the true lead-in-water levels at DC’s lead service line homes. It is important to note, however, that currently DC Water’s 2nd-draw sampling is not required under the LCR. We trust that the agency will correct its sampling instructions by 2027, when the LCRI (which requires 2nd-draw samples) comes into effect.
* EPA’s recently revised LCR—the 2024 Lead and Copper Rule Improvements (LCRI)—expands this requirement to 1st- and 2nd-draw samples at homes with a lead service line (2nd-draw samples are expected to capture lead levels in water that had extensive contact with a lead service line; as such, they can provide important information about the extent and severity of any lead contamination because lead service lines are made of 100% pure lead and are typically the greatest source of lead from plumbing). For each sampled tap, the LCRI mandates counting the higher of the two (1st- and 2nd-draw) results. This revision will go into effect in 2027.
** The LCRI lowers the lead action level to 10 ppb lead.
*** DC Water’s current 2nd-draw instruction allows letting the faucet run while emptying Sample Bottle 2 three times. This means that, by the fourth filling (which is supposed to capture the “5th-liter” or “lead service line” sample), it is likely that more than 5 liters of water have been dumped. Therefore, the water captured may not have had the required 6-hour minimum stagnation time in the lead service line. As a result, it might contain significantly lower lead-in-water levels than a true 5th-liter or lead service line sample would.
Photograph of DC Water’s current “Water Sampling Instructions” for lead