How to Survey Fire Tanks for Safe Operation

A fire tank can appear serviceable from ground level while corrosion, liner deterioration or internal component failure develops out of sight. Knowing how to survey fire tanks properly gives the responsible person evidence of the tank’s condition, its ability to support the sprinkler system, and the most proportionate route to repair, refurbishment or replacement.

For facilities teams, insurers and duty holders, the survey is not simply a visual check. It is a structured engineering assessment of an asset that may be called upon only once, but must perform without delay when that moment comes. The right survey also avoids a common and costly assumption: that an ageing tank automatically needs replacing. In many cases, targeted remedial work can extend its operational life significantly.

Start with the tank’s fire protection role

Before assessing the structure, establish what the tank is required to do. Confirm its relationship to the sprinkler installation, including the required water capacity, suction arrangements, duty and standby pumps where applicable, fill arrangements, alarm levels and the site’s operational requirements.

A surveyor should review available tank drawings, previous inspection reports, repair records and maintenance documentation. These documents help identify whether the tank has been altered, whether known defects have progressed, and whether its present configuration remains suitable for the sprinkler system it serves.

This desktop review must be checked against the physical installation. It is not unusual for site conditions to differ from historic drawings after extensions, changes to pipework, roof repairs or alterations to surrounding access. The survey should therefore record the tank type, dimensions, construction materials, approximate age, location and any restrictions that will affect access or future works.

Carry out a safe external inspection first

The external survey establishes the broad condition of the tank and identifies risks before any internal inspection is planned. Access must be controlled, particularly where roofs, ladders, elevated platforms or confined spaces are involved. A fire tank survey should be undertaken by competent personnel using suitable access equipment and a method statement appropriate to the site.

The tank base, supporting foundation and surrounding ground should be inspected for settlement, ponding water, damaged concrete, vegetation growth and evidence of leakage. Even a minor, persistent leak can undermine foundations, corrode steelwork and create a misleading impression of water loss elsewhere in the sprinkler system.

Examine the shell panels, vertical and horizontal joints, bolts, external sealants and stiffeners. Particular attention should be given to corrosion around seams, fixings and areas where water can become trapped. Galvanised steel tanks can deteriorate from the outside as well as the inside, especially where protective coatings have failed or where dissimilar materials have contributed to localised corrosion.

The roof requires equally careful attention. Check roof sheets, purlins, supports, hatches, vents, gutters and rainwater outlets for corrosion, distortion, loose components or water ingress. A compromised roof can accelerate internal deterioration, allow contamination into the stored water and create a safety issue for anyone accessing the tank.

Where fitted, inspect the low-level access housing, access doors, seals and locking arrangements. These features must remain secure against unauthorised entry while allowing practical access for inspection and maintenance.

Inspect the internal condition without unnecessary disruption

Internal condition often determines the remedial strategy, but draining a sprinkler tank solely for inspection can be operationally difficult and may require fire safety controls while the water supply is unavailable. This is why remotely operated vehicle, or ROV, inspections are particularly valuable for many live fire tanks.

An ROV can inspect the submerged tank floor, wall interfaces, liner condition, internal fittings and areas of sediment without draining the tank. High-quality recorded footage gives the surveyor and asset owner a clear record of the conditions found, while helping maintain fire water availability. It is especially useful where a tank is difficult to isolate, where business continuity is critical, or where initial evidence is needed before committing to a larger refurbishment programme.

A no-drain inspection does have limits. Heavy sediment, poor water clarity, complex internal obstructions or suspected damage above the waterline may mean that a more intrusive inspection is eventually required. The appropriate method depends on the defect risk, tank construction and the level of assurance needed. A competent survey should explain those limits rather than presenting any one method as suitable for every tank.

What to look for internally

Internal findings should be recorded systematically, with photographs or video linked to the tank location and defect area. The assessment should consider the condition of the floor, wall panels, joints, bolts, flanges, ladders, suction pipework, anti-vortex arrangements, float valves, level monitoring equipment and internal bracing.

For lined tanks, inspect for tears, punctures, lifting seams, failed welds, wrinkling, abrasion and deterioration around penetrations. EPDM linings can provide a durable refurbishment solution, but only where the substrate, detailing and installation method are appropriate. A liner defect is not always evidence that the entire lining has failed. Localised damage may be repairable, while widespread age-related deterioration may justify relining.

Where an epoxy-coated steel tank is present, identify coating breakdown, blistering, rust staining and areas of bare substrate. Fibreglass section tanks should be checked for cracking, delamination, damaged gel coat, failed joints and panel movement. The survey must distinguish cosmetic ageing from defects that affect water retention, structural integrity or sprinkler reliability.

Assess defects in terms of risk and remedial options

The most useful survey does more than list defects. It explains their likely cause, their effect on fire water storage and the practical options for dealing with them. A small roof leak, for example, may be addressed by replacing local roof sheets and purlins. Significant corrosion to panels or structural bracing may demand a broader engineering solution.

Defects should be prioritised according to immediate safety risk, risk to sprinkler water availability, likelihood of progression and the disruption involved in repair. Urgent items may include active leaks, structural instability, severely corroded roof supports, compromised access hatches or damaged suction components. Other issues can be planned into a phased refurbishment programme.

At this stage, repair versus replacement should be considered objectively. Replacement can be the right option where the tank has extensive structural failure, insufficient capacity, unsuitable configuration or repeated defects that make continued repair uneconomic. However, full replacement brings capital cost, programme implications and potential interruption to the fire protection supply.

Refurbishment may offer a more commercially sensible route where the basic structure remains viable. Depending on survey findings, this could include EPDM relining, epoxy coating, fibreglass repair, roof and purlin replacement, panel repairs, joint sealing or improvements to access arrangements. The correct choice depends on the tank’s remaining structural life, not simply its visible appearance.

Produce an evidence-led survey report

A professional fire tank survey report should give decision-makers sufficient detail to act. It should identify the tank and its intended fire protection function, record survey limitations, describe the inspection method and provide a clear condition assessment. Photographs, ROV footage where used, marked-up drawings and defect locations make the findings easier to verify and manage.

Recommendations should be prioritised and practical. Rather than stating only that a tank is in poor condition, the report should set out what needs attention, why it matters, whether temporary controls are required and what repair or refurbishment methods are suitable. Where further investigation is necessary, this should be clearly separated from confirmed defects.

The report should also support communication with insurers, fire protection contractors and senior stakeholders. Clear evidence helps demonstrate that the duty holder understands the condition of the water storage asset and is managing risks through a defined programme of work.

Plan the work around fire protection availability

Survey findings must translate into a controlled delivery plan. Before any repair, relining or replacement work begins, agree how sprinkler protection will be managed during the works. This may involve sequencing, temporary measures, impairment procedures and close coordination with the site’s fire protection contractor and insurer.

Programme planning matters as much as engineering detail. A warehouse, manufacturing facility or public building may have limited windows for taking a tank out of service. Early planning can allow refurbishment works to be carried out with less disruption than an unplanned response to a leak or failure.

Nationwide Water Solutions Ltd approaches surveys with this full lifecycle view: establish the condition, identify the real cause of deterioration, and recommend a solution that protects fire safety performance without specifying replacement where a sound repair is available.

A fire tank is a critical reserve, not a passive piece of plant. Survey it before defects dictate the timetable, and use the findings to protect both sprinkler resilience and the long-term value of the asset.