Overhead Water Tank Waterproofing in Pakistan
Overhead water tanks are among the most demanding structures to waterproof. Constant hydrostatic pressure, thermal movement, and years of structural micro-cracking all combine to cause persistent leakage. Exposure to potable water adds another layer of complexity.Grace Chemicals provides a complete overhead water tank waterproofing system using AQUAFIN-IC crystalline waterproofing technology by Schomburg Germany — a solution proven on municipal water supply projects, housing schemes, and commercial developments across Pakistan.
Our system goes beyond surface coating. We address the root causes of leakage through thorough surface preparation, proper joint treatment, and a crystalline waterproofing layer that penetrates deep into the concrete matrix to deliver permanent, active protection.
Why Overhead Water Tanks Leak
First, understanding the causes of water tank leakage is essential before any waterproofing work begins. The most common causes we encounter on site include:
- Honeycombing and poor concrete compaction: Voids left during casting create direct pathways for water ingress, especially under pressure.
- Shrinkage and structural cracks: Temperature fluctuations and structural movement cause fine cracks that widen over time, allowing water to seep through.
- Untreated construction joints : The junction between the base slab and vertical walls is the most vulnerable point in any tank. The same applies to the joint between walls and the roof slab. If these joints are not properly chamfered and treated, leakage is almost inevitable.
- Exposed and corroding steel: Shuttering dowels and tie rods left embedded in the concrete corrode over time, expanding and cracking the surrounding concrete from within.
- Pipe penetrations and sleeve failures: Unsealed or poorly sealed pipe entries are a direct entry point for water.
- Laitance and weak surface layers: A weak, powdery surface layer on the concrete prevents any coating from bonding properly, leading to delamination regardless of what product is applied.
Our Overhead Water Tank Waterproofing System
Grace Chemicals follows a strict, multi-stage system for every overhead tank project. Each stage is non-negotiable, skipping any step compromises the entire system.
Stage 1 — Complete Surface Preparation
Thorough surface preparation is the foundation of a successful waterproofing system. We do not begin any coating work until the substrate is fully prepared.
Chiseling of loose and deteriorated concrete: All loose, honeycombed, and structurally weak concrete is chiseled out completely. No loose material is allowed to remain under the waterproofing layer. This includes any deteriorated concrete around cracks, pipe penetrations, and construction joints.
Mechanical grinding: Next, we mild-sand the complete surface using a power grinder to remove laitance, weak repairs, and any adhesion-inhibiting substances from the substrate.
Compressed air cleaning: After grinding, the entire surface is blown clean with compressed air to remove all dust and loose particles.
Exposed steel treatment: All exposed shuttering dowels, tie rods, and reinforcement bars are chiseled out in a V-shape. The V-groove is cleaned and filled with INDUBOND VK 4034 epoxy mortar to protect the steel and seal the surrounding concrete.
Crack repair: All shrinkage cracks are repaired with INDUCRETE SC10, a fiber-based non-shrinkage repair mortar. This product compensates for shrinkage during curing, ensuring cracks are fully filled without further movement.
Cavity and penetration grouting: Finally, large cavities and pipe penetrations are grouted with INDUGROUT-GP, a non-shrinkage cementitious grout, to restore structural integrity before the waterproofing coat is applied.
The substrate is kept matt damp not wet, not dry at the time of waterproofing application to ensure proper bond and activation of the crystalline system.
Stage 2 — Joint Treatment
Construction joints are the most critical and most commonly neglected part of any water tank waterproofing system. Grace Chemicals treats every joint before the main coating is applied.
Chamfer formation at all connecting joints: A 3 to 4-inch chamfer is formed at all connecting joints: the junction between the base slab and walls, between walls, between walls and the roof slab, and at all parapet and column junctions. We make the chamfer using cement, sand, and zero chips, with We use AQUAFIN LATEX as a slurry bonding agent agent to ensure proper adhesion. We then apply ASOCRETE M30 smoothing compound over the chamfer to create a clean, sealed profile.
Flexi Seal joint tape at corners: Where required, We embed ASO Joint Tape or FLEECE-110 non-woven joint tape at all corner junctions and internal wall-to-slab joints using the first coat of AQUAFIN-IC. This tape bridges any movement at the joint and prevents reflective cracking through the waterproofing layer.
No joint is left untreated. The combination of a properly formed chamfer and embedded joint tape ensures that the highest-risk areas of the tank receive the highest level of protection.
Stage 3 — AQUAFIN-IC Crystalline Waterproofing Coating
Once surface preparation and joint treatment are complete, We apply AQUAFIN-IC crystalline waterproofing slurry by Schomburg Germany to all internal vertical and horizontal surfaces of the tank.
AQUAFIN-IC is a cement-based crystalline waterproofing coating that works through a fundamentally different mechanism than conventional coatings. Rather than forming a membrane on the surface, it penetrates deep into the concrete matrix. On contact with moisture, its active chemicals react with free calcium and cement particles. They form insoluble crystalline structures that permanently seal capillary pores, micro-cracks, and voids inside the concrete.
Key properties of AQUAFIN-IC:
- We apply it at 1 kg per SQM in two coats on all internal surfaces
- Penetrates the concrete substrate — cannot peel, flake, or delaminate
- Resists high hydrostatic pressure from both positive and negative sides
- Continuously active — self-heals new cracks up to 0.4 mm as they form
- Certified safe for potable water contact — suitable for drinking water tanks
- No water curing required — cures naturally in ambient conditions
- Made in Germany by Schomburg GmbH
The result is a tank that is waterproofed from within, not just coated on the surface.
Why Choose Grace Chemicals for Overhead Tank Waterproofing
German technology, locally applied — AQUAFIN-IC is manufactured by Schomburg GmbH, Germany. Grace Chemicals is an authorised channel partner for Schomburg products in Pakistan, ensuring you receive genuine material backed by the manufacturer’s technical data.
System-based approach — We do not supply material only. Our team carries out complete supply and application, from surface preparation through to final coat, following the same methodology used on every project regardless of tank size.
Potable water safe — AQUAFIN-IC is certified for use in structures that store drinking water. Your overhead tank is not just waterproof — it is safe for the water stored inside.
Proven on major projects — Grace Chemicals has applied this system on water tanks across residential, commercial, and industrial developments in Lahore, Islamabad, Rawalpindi, Karachi, Faisalabad, and project sites across KPK and Punjab.
5-year warranty: On completion of work as per our proposed system, we issue a warranty certificate against material and application.
Frequently Asked Questions (FAQs)
Get a Technical Assessment for Your Overhead Tank
If your overhead tank is leaking, showing cracks, or due for a waterproofing upgrade, contact Grace Chemicals for a site inspection and system recommendation. Our technical team will assess the condition of the tank and propose the right system for your structure.
📍 Lahore Office: 541 J3 Block, MA Johar Town, Lahore
📍 Islamabad Office: D-1, Darweish Plaza, DHA-2, Rawalpindi
📞 Call/WhatsApp: 0304-9187934
✉️ Email: [email protected]
