Tin Man
‘Tin Man’ Demolished After Over 100-Years of Service
July 17, 2019
The Maguire Iron Podcast: 5: American Water Works Association
August 5, 2019
Water Tank Inspection

Water towers are used as primary water storage for many communities. They are designed to provide safe potable water, reliable water pressure and fire protection. To keep a water tower functioning properly, annual inspections should be conducted.

Water Tank Inspection
The American Water Works Association recommends: “Tanks should be washed out and inspected at least once every 3 years, and where water supplies have sediment problems, annual washouts are recommended.”

(AWWA Manual M42, ch. 8, paragraph “Tank Washouts,” p.88)

Inspection Categories

    1. Sanitary Conditions

    2. Structural Conditions

    3. Safety Conditions

    4. Coating System Conditions

    5. Security Conditions

American Water Works Association
OSHA

Sanitary Conditions

The sanitary conditions of a water storage tank are paramount to keeping the water supply safe inside the water storage tank from outside contaminants. The items that should be inspected to make sure that they meet all OSHA and AWWA standards are:

    1. Vents – “Frost-Proof” screened vent of sufficient size.
    2. Manways – 24” opening with 4” curb and 2” overhang.
    3. Overflow Pipe – Sufficient size, screened and/or flap-gate and 18-24” from the ground

*Check your specific state regulations to make sure your tank is in compliance.

Roof Manway and Fail-Safe Vent
These are examples of a proper welded steel vent and manway that meet OSHA and AWWA standards.

Structural Conditions

The water towers structural conditions are critical to ensure that the entire structure is safe. The inspection should ensure that the structure continues to meet the original engineers’ specifications. The items that should be inspected depending on the style of tank are:

    1. Anchor Bolts – Secured and tight with no gaps between the nut and foundation plate.
    2. Foundations/Grouting – No concrete deterioration and all gaps have proper grouting.
    3. Wind Rods – Turnbuckles properly turned to tanks engineered specifications.
    4. Metal Loss in Steel Plates – Ensure no metal loss has taken place in metal plates.
    5. Roof Structures – Have no metal loss, are properly secured and are structurally sound.
Anchor Bolt
Anchor bolts improperly secured can cause structural issues.
Tank Grout
Improper and failed grout between the foundation and the tank base plate.

Safety Conditions

The water towers safety conditions are important for keeping anyone who is on or around the structure safe. The safety items that should be inspected based on the style of tank are:

    1. Railings – 42” high with a mid-rail and 4” toe plate.
    2. Ladders – 16” wide with 12” step, 3/4” non-slip rungs, 3/8” side rails and positive safety climb device.
    3. Manways – Confined space entry requires a minimum of two unobstructed 24″ openings during renovation.
Safety Climb Test
A Maguire Iron employee being trained on how to properly use a cable slider on a safety climb device.

Coating System Conditions

The water towers exterior and interior coating conditions are critical to protecting the steel from corrosion as well as protecting the potable water from the steel. Many factors effect coating performance. That is why it is critical to inspect all aspects of the tank for coating failures, especially areas of the tank that are exposed to moisture, both internally and externally.

Proper coating adhesion and film thickness should be measured by a N.A.C.E certified coatings inspector to determine how the coatings are preforming and what the future needs of the coatings will be.

Water Tank Inspection
A coating thickness test being performed by a Maguire Iron N.A.C.E. Level 3 Coatings Inspector.
Water Tank Inspection
A coating adhesion test being performed by a Maguire Iron N.A.C.E. Level 2 Coatings Inspector.

Security Conditions

The security of a water tank is paramount for ensuring the safety and quality of the structure and the potable water that it stores. There are multiple best practices to keep your tank and site secure based on the style of tank:

    1. Terminate exterior ladders at least 12ft above grade.
    2. Properly fence site.
    3. All doors and access hatches have proper locks.
    4. Visit site on regular basis.
    5. Install alarm system.
    6. Install ladder gates to discourage ladder access.
Water Tank Inspection
A water tank site with proper fencing, signage and locked gate.

In Summary

Safe water is the number one purpose of a water storage tank. A proper inspection, performed by a trained professional in the five inspection categories can alert you to any current issues or give you information on future issues that need to be addressed.

At Maguire Iron, we provide a full range of inspection services and maintenance plans tailored to your water tanks specific needs and budget. Call us today at 605-334-9749 to schedule an appointment with one of our water tower experts to determine your tanks condition and the best way to manage one of your most important pieces of infrastructure.