Water tank waterproofing for duplexes in Allith

Prepared by the technical team · editorial review · last updated 13 November 2026 · Sources

Why water tank waterproofing differs in Allith

The centre of Allith sits about 5 m above sea level (SRTM open elevation data). Allith is about 1.2 km from the sea coast (OpenStreetMap).

Main roads in or near Allith: Al Laith Road, Amr Bin Al Aas Street.

Water tanks on duplex roofs in Allith face a familiar problem: the tank sits exposed to daily heat and then cooler nights, which causes the concrete or plaster lining to crack. Once hairline cracks open, water seeps out through the walls and floor, staining the ceilings below and sometimes reaching the shared wall between the two units. Because a duplex has two households drawing from one or more tanks, a leak in one unit can quickly become a dispute about who pays for the repair. Checking the internal lining and the joints around the inlet and outlet pipes is the first step any careful inspection should take.

The local setting changes how the work should be approached. The centre of Allith sits about 5 m above sea level, and the town is about 1.2 km from the sea coast. That combination means the air is humid and salty, which speeds up corrosion of exposed metal fittings and can weaken cement-based coatings over time. A tank internal coating, typically priced at SAR 25–60 per m², is often the most sensible choice for a duplex tank, because it seals the interior surface where the water is held. For the roof surface above, liquid roof waterproofing at SAR 8–25 per m² or a bitumen membrane at SAR 15–35 per m² can protect the slab from the same humid, salt-laden air. Where a crack is already visible, crack injection at SAR 40–120 per m is usually needed before any surface coating is applied.

Before booking a visit, ask the provider to confirm which surfaces they plan to treat, since a tank, a roof slab and a bathroom wall each need different materials. Ask how they will prepare the surface, whether they will drain and clean the tank, and how long it will stay out of use. Request a written breakdown that shows the per-square-metre rate for each material, so you can compare it with the ranges above. Finally, ask who will inspect the adjoining unit, because a duplex shares walls and pipes, and a clear agreement at the start prevents problems later.

In a duplex, the two floors often share lines, so tests are done floor by floor.

Signs worth paying attention to

These are the signs most often linked to water tank waterproofing:

• A tank that leaks after testing
• Deposits and flaking inside the tank
• Unusual colour or taste in the water

The most common causes

• Damaged old coating.
• A common cause: cracks in the walls or floor.
• A common cause: construction joints.

Tools we use in Allith

The steps in order

1. Emptying and ventilation: The tank is emptied and ventilated before entry.
2. Cleaning and preparation: Loose material is removed down to a sound surface.
3. Crack treatment: Active cracks are treated first.
4. Coating layers: A material intended for drinking-water tanks is applied.
5. Disinfection and fill test: The tank is disinfected and the level is monitored after filling.

Allith in facts and sources

Questions from Allith

Mistakes that cost more

• Using a material that is not intended for drinking water

What you receive

The written output: the material name, its batch number and the fill-test result. The report is numbered and can be checked with its verification code.