May 7, 2024 | Susan Napier-Sewell

Good Intentions Need to be Supported by Good Communication: Water Leak Incident

water leak

A Facility Point of Contact (FPOC) was called to get a water leak under the sink in a kitchenette off the high-side atrium in B140 corrected.

Upon arrival, the Facility Coordinator (FC) noticed that an ice-cube bin collecting a water leak from the instant-hot water tank under the sink was overflowing. It is not known when the bin was placed there or by whom. The FC emptied the bin, returned it to the same location, and observed the leak. At only 15 to 20 drops per minute, the leak appeared to be slow. The
FC decided that a different work order scheduled for work that day could be completed in the interim. The work order for the leaking instant-hot unit was submitted by close of business the same day.

On the day the leak repair was scheduled, approximately 15 days after the work order was submitted, the instant-hot unit was discovered to have overheated.

water leak

Figure 1. Instant-hot faucet at sink level (circled).

water leak

Figure 2. Instant-hot faucet and tank when new.

water leak

Figure 3. Overheated instant hot-water tank.


Examination of the damaged unit determined that the water supply valve was closed while the unit was plugged in to the outlet under the sink. When the unit’s water temperature feedback loop detects that the water in the tank is at the dispensing temperature, the internal heating element shuts off
automatically. However, with no water in the tank, the dispensing temperature could not be achieved. This resulted in the internal heating element staying turned on and the unit overheating.

The FC assumed that A) the water leak from the tank meant that the supply water was turned on and the tank was constantly refilled, and B) the ice cube bin meant that somebody not identified to the FC was tending to the leaked water. The slow leak rate, combined with these two assumptions, led the FC to believe that the instant-hot could remain in service pending repair of the leak.

It is possible that the water supply was on during the FC’s initial visit and turned off by somebody else after the FC’s visit. It is also possible that the water supply was turned off before the FC’s initial visit and the FC arrived before all of the water leaked from the tank. This may be why the leak was as slow as it was. This kitchenette is accessible to and used by multiple people, so it is possible that multiple people other than the FC were involved.

Also unknown is whether, before or after the FC’s visit, anybody ever unplugged the instant hot unit only to have somebody else plug it back in to the electrical outlet.

Although the overheating would have been prevented if the instant hot was disconnected from power and remained disconnected from power OR the water supply was not turned off, the primary contributor to this water leak event appears to be the absence of the communications needed to establish and maintain control over the leaking instant-hot unit.

Recommended action

General: When a device is not working properly, it should be:
• Brought to the attention of appropriate personnel (e.g., FPOC or FC) as soon as possible.
• Placed under the control of one individual (e.g., FPOC or FC).
• Removed from service with appropriate controls applied.
• Marked appropriately: the status of the affected device plus any other devices affected as a result of removing the affected device from service, any prohibitions regarding use of any of the affected devices (e.g., DO NOT USE), actions taken/planned (e.g., repair ticket initiated and date), the name
and contact information for the person controlling the device.

NOTE: Other devices may be affected because they share supply or other connections such as drains or exhausts with the affected device. For example, if the valve that controls water to this instant-hot also
controls the water to the sink faucet, removal of the sink faucet from service would have to be identified and communicated, too.

As applied to this instant-hot water heater, the actions would have been
• The person who detects the leak immediately brings the leak to the attention of the FPOC or FC.

• The FPOC/FC:

  1. addresses any leaked/leaking water,
  2. removes the instant-hot from service by unplugging the device and turning off its supply water,
  3. applies appropriate tags and devices (if any) to the plug and water valve to prevent restoring power and water to the unit,
  4. tags/posts information providing the unit’s status, the prohibitions (do not use, plug in, and/or turn on water to the instant-hot). regarding use of the device (e.g., DO NOT USE), actions taken/planned (e.g., repair ticket initiated and date), the name and contact information for the person controlling the device (see second bullet).

Source: DOE, OPEXshare, “Good Intentions Need to be Supported by Good Communication,” 11/05/2021, Lawrence Livermore National Security (LLNS).

Accident, Investigations
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