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How Do I Clean an Atmospheric Storage Tank?
Atmospheric tanks require regular cleaning to maintain water quality. Their open design makes access straightforward, allowing for thorough sanitization.
Understanding Atmospheric Tanks
Atmospheric storage tanks differ from pressurized systems in several important ways. These tanks operate at ambient pressure and feature either an open top or a vented design that allows air exchange with the surrounding environment.
Because they are not sealed under pressure, atmospheric tanks allow direct access to interior surfaces, making hands-on cleaning both possible and practical. This accessibility is one of the key advantages when it comes to maintenance.
Unlike pressurized tanks that require depressurization and specialized procedures, atmospheric tanks can be entered, inspected, and cleaned with relative ease. However, this open design also means these tanks may be more susceptible to contamination from airborne particles, algae growth, and sediment accumulation, making regular cleaning essential.
Preparing and Draining the Tank
Safety First
Before beginning any cleaning procedure, ensure the water supply to the tank is shut off. If your system includes pumps or other electrical components, disconnect power to prevent accidental activation during the cleaning process.
Draining the Water
Locate the drain valve at the bottom of your atmospheric tank and open it to release the stored water. Allow the tank to drain completely, as residual water can dilute cleaning solutions and reduce their effectiveness. Depending on your tank size and drain configuration, complete drainage may take anywhere from several minutes to an hour or more.
Once the bulk of the water has drained, you may notice sediment or debris remaining at the tank bottom. This is normal, especially if the tank has been in service for an extended period without cleaning. This sediment will be addressed during the scrubbing phase.
Scrubbing Interior Surfaces
Accessing the Tank Interior
With the tank fully drained, access the interior through the tank opening or access port. For larger tanks, you may need to physically enter the tank.
Always ensure adequate ventilation and consider having a second person present for safety when working inside enclosed spaces.
Never enter a tank if you feel lightheaded or if airflow is inadequate; confined-space hazards can be dangerous.
Cleaning Technique
Using a soft-bristled brush or non-abrasive scrub pad, thoroughly clean all interior surfaces of the tank. Pay particular attention to:
- The tank bottom where sediment can accumulate
- The waterline area where mineral deposits and biofilm can form
- Corners, seams, or any areas with irregular surfaces
- Inlet and outlet fittings
Avoid using steel wool, wire brushes, or harsh abrasive materials that could scratch or damage the tank surface. Scratches create microscopic areas where bacteria can harbor and multiply, compromising future water quality.
Removing Stubborn Deposits
For mineral scale or stubborn buildup, a solution of white vinegar and water can help loosen deposits before scrubbing. Allow the solution to sit on affected areas for 10-15 minutes before scrubbing. Rinse away loosened material before proceeding to sanitization.
Applying Sanitizing Solution
Preparing the Sanitizing Solution
A diluted chlorine bleach solution is effective for sanitizing water storage tanks. Use 1 tablespoon of unscented household bleach (5–6% sodium hypochlorite) per gallon of water. For larger volumes, this equals approximately 1/4 cup per 10 gallons.
Application Method
Apply the sanitizing solution to all interior surfaces of the tank using a clean spray bottle, sponge, or by pouring the solution along the tank walls. Ensure complete coverage of all surfaces, including the underside of the tank lid or cover if applicable.
Allow the sanitizing solution to remain in contact with all surfaces for a minimum of 10 minutes. This contact time is essential for the chlorine to effectively eliminate bacteria, algae, and other microorganisms. For tanks with heavy contamination or visible biofilm, extend the contact time to 20-30 minutes.
Important Considerations
Work in a well-ventilated area when using chlorine-based sanitizers. Avoid mixing bleach with other cleaning products, particularly those containing ammonia, as dangerous chemical reactions can occur. If you prefer not to use chlorine, food-grade hydrogen peroxide solutions or NSF certified sanitizers offer effective alternatives.
Thorough Rinsing
Initial Rinse
After the sanitizing solution has had adequate contact time, rinse all interior surfaces thoroughly with clean, potable water. Use a hose or bucket to flush the sanitizer from all areas of the tank, directing the rinse water toward the drain.
Complete Residue Removal
Continue rinsing until you can no longer detect any chlorine odor inside the tank. Residual sanitizer can affect water taste and quality, so take the time to rinse thoroughly. For best results, perform at least two complete rinse cycles, allowing the tank to fill and drain fully between each rinse.
Final Inspection
Before returning the tank to service, conduct a visual inspection of all interior surfaces. They should appear clean with no visible residue, discoloration, or remaining deposits. Check that the drain valve is functioning properly and that all fittings are secure.
Returning to Service
Close the drain valve securely and restore the water supply to the tank. Allow the tank to fill completely, then check for any leaks around fittings, valves, or access points. Your atmospheric tank is now clean, sanitized, and ready to provide quality water storage.
Recommended Cleaning Schedule
For optimal water quality and tank longevity, we recommend cleaning your atmospheric storage tank at least once per year under normal conditions. However, more frequent cleaning may be necessary if you notice changes in water taste, odor, or appearance, or if the tank is exposed to conditions that promote contamination.
Regular inspection between cleanings helps you identify potential issues early and maintain the highest water quality standards. If you have questions about your specific tank or encounter unusual conditions during cleaning, our Crystal Quest support team is here to help.
