A Concrete Tank Relining Case Study in Capacity Recovery

A tank does not have to collapse to become an operational risk. In this concrete tank relining case study, an ageing reinforced concrete potable water tank showed the familiar signs of decline: damp external areas, local cracking, a friable internal surface and growing concern over water quality protection. The structure was still viable, but its original water-retaining surface was no longer a dependable barrier.

For the facilities team, the question was not simply whether to repair the tank. It was whether the tank could be returned to service without the disruption, programme risk and capital cost associated with demolition and replacement. A properly specified relining system provided the answer.

The project brief: retain a viable concrete structure

This representative case reflects the issues found regularly during surveys of commercial and industrial water storage assets. The tank served a multi-occupancy site with a continuous demand for stored potable water. Taking it out of service required careful planning around isolation, temporary supply arrangements and the site’s wider operational needs.

Internal inspection identified surface degradation across the floor and lower wall sections. Historic moisture movement had contributed to cracking around construction joints, while areas of the concrete had become uneven and porous. Although there was no evidence that the tank shell had reached the end of its structural life, the internal face could no longer be treated as a suitable long-term potable water contact surface.

Full replacement was considered. In practical terms, however, replacement would have meant removing a substantial concrete asset from a constrained location, dealing with access limitations and extending the period in which storage capacity was unavailable. The more proportionate route was to repair local defects, isolate the stored water from the existing concrete and install a purpose-designed liner.

Why concrete tanks become difficult to manage

Concrete is a durable construction material, but it is not maintenance-free. Over time, the combined effects of carbonation, water ingress, movement, poor historic repairs and cleaning can alter the condition of the tank’s internal surface. In buried or partially buried installations, external groundwater pressure and limited access can make diagnosis more complicated.

For potable water applications, the concern is not solely visible leakage. Rough, cracked or porous surfaces can be harder to clean effectively and may allow debris or localised contamination to accumulate. Defects around pipe penetrations, joints and upstands also require attention because they can undermine the tank’s watertightness and hygiene controls.

Relining is not a substitute for structural assessment. Where there is significant movement, unstable concrete, reinforcement failure or a major load-bearing defect, wider structural works or replacement may be required. The value of a survey is that it separates remediable lining defects from issues that demand a different solution.

Survey findings and the relining decision

The survey focused on four questions: whether the concrete shell remained structurally sound, where water was entering or escaping, what repairs were needed before lining, and whether the proposed materials were suitable for the stored water and operating environment.

The tank had sufficient structural integrity to be retained. Cracks were assessed, defective areas were identified for local repair, and the condition of penetrations and joint details was recorded. The survey also reviewed access, isolation points, drainage arrangements and the practical route for bringing materials and equipment to the tank.

That early planning matters. A lining system is only as effective as the preparation, detailing and installation behind it. A specification that overlooks an awkward penetration or inaccessible corner can create unnecessary risk later in the project.

The selected approach was a flexible polypropylene tank lining system, configured to form a new internal containment barrier. This approach was suited to the tank because it reduced reliance on the condition of the old concrete surface as the primary water-retaining layer. Unlike a coating, which is applied directly to a prepared substrate, a flexible liner can accommodate minor surface irregularities once defects have been properly addressed.

Preparing the tank for a new lining system

Before installation, the tank was isolated, drained and cleaned to provide a safe working environment. Loose material, deposits and unsound repairs were removed, allowing the true condition of the concrete to be inspected. Local defects were repaired, sharp projections were addressed and areas likely to affect the liner were made suitable for installation.

The works also included detailed attention to interfaces. Pipe entries, outlet arrangements, internal columns, access hatches and changes in level are often where tank refurbishment succeeds or fails. Each feature must be incorporated into the lining design so that the finished system remains secure, cleanable and watertight in service.

In a potable water tank, hygiene controls apply throughout the programme. The work area must be managed to prevent avoidable contamination, and materials must be appropriate for their intended water contact duty. On completion, cleaning, inspection and recommissioning procedures should be agreed with the responsible site team before the tank returns to use.

Installing the concrete tank relining system

The liner was manufactured to suit the surveyed dimensions and internal geometry, then installed within the prepared tank. The system created a continuous internal barrier between the stored water and the deteriorated concrete. Edges, seams and penetrations received particular attention, as these details determine the long-term performance of any lining installation.

This was not a cosmetic improvement. The purpose was to establish a controlled, durable containment surface that could support the site’s water hygiene and asset management objectives. The original concrete structure continued to provide the tank’s form and structural capacity, while the liner took over the role of the primary internal water-retaining surface.

The installation programme was planned around the site’s operational constraints. For many commercial premises, the practical benefit of relining is not merely a lower capital cost. It is the ability to retain a serviceable tank shell, avoid major demolition works and reduce the uncertainty that can accompany a replacement project in a confined plant area.

Nationwide Water Solutions Ltd manufactures specialist lining systems in-house, allowing tank lining details to be developed around the actual condition, dimensions and service requirements of the asset rather than forcing a standard solution onto an unusual tank.

The operational outcome

Following inspection and recommissioning, the tank had a new internal containment surface and a clearer maintenance position. The site avoided the immediate need for replacement, retained its existing storage footprint and reduced the risks associated with degraded concrete in a potable water environment.

Just as importantly, the project produced a documented basis for future maintenance. The facilities team had an understanding of the repaired areas, lining arrangement, access constraints and recommended inspection points. This is valuable when responsibility for a building changes hands or when future water hygiene reviews are undertaken.

A relined tank will still need planned inspection and cleaning. Lining does not remove the need for good tank management, secure access covers, effective overflow protection or periodic checks of fittings and internal condition. It does, however, turn a vulnerable surface into a manageable asset where the underlying structure remains fit for purpose.

When relining is the right route

Concrete tank relining is particularly effective where the tank shell is fundamentally sound but the internal surface has deteriorated, cracked or become difficult to maintain hygienically. It can also be a strong option where replacement access is poor, a tank is below ground, or the site cannot accommodate prolonged construction activity.

The correct solution depends on the stored liquid, tank use, structural condition, dimensions, access and required outage period. Potable water, process water, sprinkler storage and chemically aggressive liquids all demand different considerations. In some cases, an epoxy coating system may be appropriate; in others, a flexible liner offers the more practical long-term containment solution.

The first step should be a competent tank survey rather than an assumption that replacement is inevitable. A viable concrete tank is a substantial asset. With the correct repairs, lining system and installation controls, it can continue serving the site safely and reliably for years to come.

If a concrete tank is showing cracking, seepage, surface breakdown or hygiene concerns, early assessment gives you more options and more control over the eventual programme.