Water Tank Waterproofing in Riyadh

The first test needs no tools. Note the water meter in the evening once everything is switched off, then again in the morning before anyone uses water. If it moves, something is losing water continuously, but that something could be the float valve, a buried supply line or the tank. The bill alone cannot tell you which, because it lumps every loss into one number.

To separate the sources, we isolate the tank by closing the inlet and outlet valves, fix a reference mark at the water surface and watch it. A level that holds points to the pipes, pump or fittings; a level that falls points to the tank body or the openings passing through its walls. When the fall stops at a certain height, the defect usually sits at that height.

A third culprit is often overlooked: a float valve that does not shut fully, sending water out through the overflow pipe outside or into the courtyard without a single crack in the tank. That is why the float and the overflow outlet are checked before anyone recommends wall waterproofing, which in that case would change nothing about the loss.

• Meter moves with every tap closed
• Pump starts and stops with no visible use
• Damp or sunken paving beside a ground cistern
• White salt deposits or stains on the tank wall
• Float valve refilling often despite low use

Well-placed concrete holds water across most of its area, so leaks cluster at the exceptions: the construction joint between floor and wall, the points where inlet, outlet, overflow and washout pipes pass through, the frame around the access opening, honeycombed pockets left where concrete was poorly compacted, and form-tie holes that were never fully plugged.

Not every crack is the same. A fine shrinkage crack is usually static and can be treated by penetrating or injected repair, while a crack caused by soil settlement or thermal movement opens and closes with the seasons, and a rigid material over it simply splits again. Identifying the crack type comes before choosing the product, never after.

Testing at different water levels pins down the defect: if the fall stops at one height the leak sits there, and if it carries on to the floor the fault is lower down. The roof slab and the opening frame do not lose water, but they let in dust, wash water and rain, which is a separate harm and just as worth fixing.

• Floor-to-wall construction joint
• Inlet, outlet and overflow penetrations
• Access opening frame and cover
• Honeycombed pockets and form-tie holes
• Wall-to-wall corners

No system is best in every case; the right one is the one that matches the tank. Crystalline cementitious waterproofing sends its active chemicals into damp concrete pores and grows crystals that block them, so it suits wet surfaces and leaks arriving from behind. Potable-grade epoxy forms a smooth, tough film that is easy to clean, but it needs a dry, clean surface with no moisture pushing from behind.

Liquid or sheet membranes belong mostly outside the tank, on the roof slab or on an exposed outer wall, and go inside only when the product is made for drinking-water contact according to its data sheet. The right answer often combines two systems: crystalline or repair mortar as the base layer, then epoxy as a finish where a smooth surface is wanted.

Three questions settle the choice. Is the concrete dry or damp at application time? Are the cracks static or moving? Is the wall under water pressure from behind? Once those are answered, we read the product data sheet to confirm suitability for household water contact. Ground cisterns, epoxy-lined concrete and rooftop tanks each have their own dedicated page.

The commonest cause of peeling is not the material but what lies beneath it. Weak surface laitance, scale and lime deposits, old paint films and fine dust all stop the new layer from bonding. They are removed by high-pressure washing or mechanical grinding until sound, open-pored concrete is exposed, and the surface is then sounded by tapping to find hollow areas the eye cannot see.

Repair follows: cracks are opened and cleaned, then injected or filled with non-shrink mortar, and the corner between wall and floor is rounded with repair mortar into a gentle curve, because a sharp corner thins the coat and cracks there first. Form-tie holes and honeycombed pockets are filled, and the surface is washed again and left to settle before coating.

Then comes curing, a stage that cannot be shortened. Cementitious products need moisture and protection from rapid drying, and epoxy needs the temperature and time stated in its data sheet. When that period ends the tank is rinsed, filled and its level watched before use. Filling early out of impatience can ruin a coating that took real effort to apply.

Cleaning removes silt, algae and slime from the walls, but it does not change how permeable the concrete is. A spotless tank can lose water at exactly the rate it did before it was washed. Waterproofing treats the wall itself: the cracks, pores and joints that form the path the water takes.

The two services do follow each other within one job, though. We empty and wash so the bare concrete shows, which reveals cracks hidden under sediment; then we repair and waterproof, and afterwards the tank is rinsed and disinfected before refilling. Coordinating both in one visit spares you emptying the tank twice and losing supply twice.

If your tank loses no water and only needs washing or disinfecting after dust or a long period of use, that is a separate service and waterproofing is not part of it. Waterproofing is a decision built on diagnosis, not an extra to be added to every wash.