Storage Tank Inspections
The Storage Tank Rule (Section 11.28 of Regulation 11) requires all public suppliers of water with finished water distribution system storage tanks to conduct comprehensive storage tank inspections every five years or on a department accepted alternative schedule. Suppliers operating such tanks must complete their first comprehensive inspection on or by April 1, 2021 and subsequently every five years thereafter. Finished water storage tanks that are not inspected and maintained can present a pathway for microbial contamination into the tank, which constitutes a sanitary defect.
While inspection of water tanks should be a priority, please be aware that operator safety is of paramount importance when conducting tank inspections, especially comprehensive inspections. Never inspect a tank if there is any question about the safety of the personnel involved.
Comprehensive tank inspections are more robust than periodic inspections and include a thorough inspection of all external and internal components of the storage tank. As with periodic inspections, the goal of completing comprehensive tank inspections is to identify any sanitary defects that could be present. These defects cover all aspects of the condition of the storage tank including but not limited to sanitary, structural, and coating systems conditions, as well as security and safety concerns.
Common examples of tank sanitary defects identified during inspections include, but are not limited to, the following:
- Access opening with no sanitary seal (i.e., metal on metal hatch) or a damaged gasket.
- Unscreened tank vent or overflow.
- Blistering of interior coating to the degree where it is peeling into the water.
- Greater than one inch of sediment on the tank floor.
- Unsealed or inadequately sealed tank penetrations.
- Visible contamination inside the tank.
The inspection method that the supplier chooses to complete a comprehensive inspection largely depends on the type of storage tank being operated and whether the tank can be pulled off line. In some cases, the supplier may choose to contract with a company that dives into the tank to inspect it internally with the use of both video and still photos.
At the conclusion of the inspection, the contractor will typically provide the supplier with a written inspection report. The department has reviewed numerous comprehensive tank inspection reports and has frequently found that the reports have identified what the department deems a sanitary defect but the report states the defect as a recommendation or in some cases there is no mention of any needed follow-up action. If the inspection report includes any finding that constitutes a sanitary defect as a recommendation or does not mention that any action is needed, the supplier must respond to it as a sanitary defect. The supplier needs to include and complete a corrective action schedule for any sanitary defect in the written inspection plan. Failing to do so results in a treatment technique violation of Regulation 11 that requires notification to the department no later than 48 hours after the violation occurs and completion of a Tier 2 public notice.
Please keep in mind that it is the responsibility of the supplier to understand what constitutes a storage tank sanitary defect and to correct it. The department’s tank inspection checklists highlight in bold which questions are sanitary defects depending on a Yes or No answer. These checklists are available on our website.
In addition, the department has a Sanitary Defect Applicability Policy (Safe Drinking Water Program Policy # DW-010) that outlines what constitutes a sanitary defect in water distribution systems including storage tanks. This policy is available on the drinking water policies webpage.
For questions concerning finished water storage tank inspections and what constitutes a sanitary defect, please call the department at 303-692-3500.
➽ Cathy Heald, Non-Community Groundwater Unit Manager
