Concrete Tank Waterproofing in Riyadh

Concrete looks solid, but it holds a network of capillary pores left behind when surplus mixing water evaporated. With constant contact, moisture creeps through that network and dissolves some lime, leaving white deposits and sometimes cloudiness, and eventually reaches the reinforcement, rusting it and pushing off the cover concrete.

A rough surface has another effect: every bump and tiny pore is a place for sediment and thin biofilm to cling, so the wall is hard to clean fully and odour or cloudiness returns soon after each wash. A smooth lining suited to drinking-water contact closes those pores, reduces what sticks and makes the wall easier to wash and rinse.

A lining is not an end in itself, though. If the concrete is crumbling, the cracks are still moving or groundwater is pushing from outside, paint alone will not solve it and may flake within months. So the work begins by checking whether the wall can accept a lining at all.

• White deposits or yellow staining on walls once emptied
• Sandy or flaking render or concrete surface
• Cloudiness or taste that returns after each wash
• Damp seepage on the outer face of the wall
• Exposed reinforcement or visible rust marks

The first question is not which material but what condition the surface is in. Solvent-free epoxy gives a smooth, easy-to-clean finish, but it needs sound, dry concrete with moisture inside the limits of its data sheet. Polymer-modified cementitious systems tolerate a damper surface and go on by brush, though the finish stays rougher and less able to bridge moving cracks.

Crystalline products work differently: with moisture present they penetrate the pores and grow crystals that block the capillaries from inside, without forming a surface film. That suits capillary seepage in damp concrete, and does not replace repairing a crack or honeycomb. It may be combined with an epoxy coat, but compatibility between the two products and the manufacturer’s instructions decide that, not the other way round.

The most expensive is not automatically the best fit. A small tank with sound walls may be well served by a properly prepared cementitious lining, while an old tank with heavy scale that needs frequent washing benefits from smooth epoxy. We lay out the options after inspecting the surface and measuring its moisture, and explain why we picked what we did.

Linings usually fail because of what lies beneath them, not the product. Weak render, laitance and scale are removed mechanically by grinding or high-pressure water until we reach sound concrete with a rough profile that grips the material. The walls are then sounded by tapping to find hollow areas where the render has parted from the concrete, and all of it comes off before coating.

Next we repair honeycomb with non-shrink repair mortar, open and fill cracks with a material suited to the crack type, and form a rounded fillet where floor meets wall instead of a sharp corner where stress and standing water collect. We do not rely on looks; a small adhesion test patch confirms that the lining will hold.

Moisture is measured, not judged by eye. We use a moisture meter or a plastic-sheet test taped to the wall for several hours; if droplets or darkening appear beneath it, the wall is still releasing moisture and needs time, or its source needs fixing before any coating. Epoxy over damp concrete is the quickest route to blisters.

There is no single figure for every tank. The time set by the data sheet depends on the product, wall temperature, number of coats and ventilation inside the tank. In Riyadh the surface may feel dry quickly in hot, dry air, but the chemical cure deeper in the film is slower than the apparent drying, and that is where the usual mistake happens.

Once cure is complete we do not simply fill and hand over. The tank is washed and rinsed several times with the water drained, then disinfected at a suitable concentration and rinsed again until no taste, odour or foam remains. It is then filled and the level watched to see whether it holds, a step that exposes any leak not visible during drying.

We also suggest holding off drinking and cooking with the tank water until any taste or odour has gone and the team has confirmed the rinse. If your home has a water filter, it is sensible to check its cartridges after the first fill. Rushed refilling is the commonest cause of taste complaints after waterproofing.

A new tank needs an assessment, not an automatic decision. Fresh concrete is still losing moisture in its first months and releases high alkalinity that can affect some coatings, so it is given time before lining or a moisture-tolerant system is chosen. If the pour is clean with no honeycomb, treating joints and corners with a light cementitious lining may be enough.

With an old tank, the inspection decides. If deterioration is confined to limited patches of honeycomb, hairline cracks or hollow render, spot repair with lining of the damaged zones is more suitable and more economical. If scaling, deposits and seepage run across most walls, a full lining makes more sense, because patching half a wall leaves weak boundaries between old and new.

There are cases where an internal lining is not the answer: wide cracks that are still opening, soil settlement, or groundwater pushing from outside that lifts and blisters the lining. Those call for a structural assessment or treatment from the outer side, which the underground tank waterproofing service addresses.