{"id":7495,"date":"2018-02-26T15:35:18","date_gmt":"2018-02-26T20:35:18","guid":{"rendered":"http:\/\/blogs.edf.org\/health\/?p=7495"},"modified":"2025-07-08T15:14:01","modified_gmt":"2025-07-08T20:14:01","slug":"lead-hot-water-issue-worth-testing","status":"publish","type":"post","link":"https:\/\/blogs.edf.org\/health\/2018\/02\/26\/lead-hot-water-issue-worth-testing\/","title":{"rendered":"Lead in hot water \u2013 an issue worth testing"},"content":{"rendered":"

[pullquote]Preliminary testing results:<\/strong> 50% (7 of 14) of water heater tanks tested in child care centers had levels over 50 ppb with one at 2,680 ppb. For all but one of these, flushing through the tank drain significantly reduced the lead levels in the water heater. At the hot water tap, only 4 of 161 (2%) samples were above\u00a0EDF’s action level<\/a> (3.8 ppb). Water heaters may function as \u201clead traps,\u201d but more investigation is needed. Best to avoid using hot water for cooking or drinking.[\/pullquote]<\/em><\/p>\n

Tom Neltner, J.D.<\/em><\/a>,\u00a0<\/em>is Chemicals Policy Director. Analysis conducted by Lindsay McCormick<\/em><\/a>, Project Manager.<\/p>\n

Last March, I was giving a talk on lead and drinking water at the National Lead and Healthy Housing Conference. A questioner from a state health department asked me why the standard lead testing methods only sample cold water when experience suggests that people use hot water when making infant formula, dissolving powered drinks, and cooking food. After mumbling for a few minutes that people are supposed to drink cold water, I realized that I really didn\u2019t know the answer \u2013 but should.<\/p>\n

When risk assessment ignores real life, we are bound to miss something important. For hot water, I think we may\u00a0be.<\/p>\n

<\/p>\n

Hot water is likely to leach more lead from solder and brass than cold water. EPA makes this clear in its model public education<\/a> and consumer notices<\/a> for public water systems which state:<\/p>\n

Use cold water for cooking and preparing baby formula. Do not cook with or drink water from the hot water tap<\/strong>; lead dissolves more easily into hot water. Do not use water from the hot water tap to make baby formula.<\/p>\n

In addition, if the water comes through a lead pipe, it may contain particles of lead if the pipe is disturbed. The most common example of this situation occurs with a lead service line (LSL) \u2013 \u00a0which connects the drinking water main under the street to the building \u2013 is disturbed. The lead particulate from the service line likely settles and accumulates at the bottom of the hot water tank where high temperatures from the flame or electric heater coil may dissolve the lead into the water. The settled particulate could also be re-suspended when water flow is high.<\/p>\n

\"\"<\/a>This issue became evident in an ongoing EDF pilot project to comprehensively evaluate and reduce lead in drinking water at child care centers. As part of this pilot, we are measuring lead levels in water taken from all faucets. To explore this concern of lead in hot water, we also included hot water samples from the faucets used for drinking water and directly from the drain valve of the water heater (see photo).\u00a0After letting the water stagnate overnight to provide us with a worst case sample, our partners in Chicago, Illinois; Grand Rapids, Michigan; Cincinnati, Ohio; and Starkville and Tunica, Mississippi sampled the first \u00bc liter of hot water at the faucets commonly used for drinking water. They also collected two consecutive \u00bc liter samples from the drain of the hot water heater tank after flushing the line for five seconds. See the full protocol here<\/a>.<\/span><\/p>\n

Overall, we were encouraged to find relatively low levels of lead in most faucets tested in the child care centers. After testing hot water at 161 faucets in 11 child care centers, we have only found lead levels over EDF’s action level<\/a> of 3.8 ppb in 4 of the first draw samples (2% sampled). The vast majority of hot water samples (83%) had non-detectible lead concentrations.<\/p>\n

\"\"<\/a>
Water samples collected directly from water heater drain. Initial draw pictured on the left.<\/figcaption><\/figure>\n

However, the lead levels in samples taken from hot water heaters are alarmingly high, with 7 of 14 water heaters tested having at least one sample with lead levels above 50 ppb. See Figure 1 and Table 1 below. One water heater had levels as high as 2,680 ppb. The initial samples from the water heater often were discolored \u2013 some even like a sludge.<\/p>\n

Despite still being in the middle of the project, we are choosing to share the results of what we are seeing, and we will keep you informed as we get further results.<\/p>\n

\"\"<\/a>
Figure 1: Measured lead levels in \u00bc liter of water drained from 14 hot water heaters in 11 child care centers. Highest lead level detected during each sampling phase \u2013 the initial sampling (pre-flush), following a full flush of the water heater (post-flush), and following a second flush of the water heater (second post-flush). Lines connect data for a single water heater.<\/figcaption><\/figure>\n

Our partners performed sustained flushes through the drain on 10 water heater tanks. The flushing helped significantly in almost every case. Among water heaters where\u00a0water levels first tested above 50 ppb, flushing dropped the lead levels on\u00a0average from 456 ppb to 20 ppb.[1]<\/sup><\/a> When levels in the water heater initially tested below 50 ppb, the drop was less evident (from 17 ppb pre-flush to 13 ppb post-flush, on average). Our partners performed second flushes with mixed results in two cases in an attempt to further reduce the lead levels. See additional detail in Figure 1 above and Table 2 below<\/a>.<\/p>\n

\"\"<\/a><\/p>\n

Our project is ongoing. So far, our takeaways are:<\/strong><\/h3>\n