Basement, Water Tank & Sump Waterproofing

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Basements and lift pits that stayed dry all year start weeping when the monsoon raises the water table. Water tanks lose level overnight. These are hydrostatic-pressure problems — they need crystalline or polymer-modified cementitious systems engineered for water-retaining and below-grade structures. This collection includes crystalline waterproofing mortars, two-pack cementitious systems and flexible protective coatings suitable for basements, underground sumps, lift pits and water tanks (check each product page for potable-water approvals). Read the complete basement waterproofing guide for positive vs negative side strategy, and estimate quantities with the calculator . What Is the Best Waterproofing for Underground Water Tanks in India? For underground water tanks storing potable (drinking) water, use crystalline cementitious systems like MC-Special DM applied to the water-facing surface (positive side). For non-potable tanks, two-component flexible cementitious coatings such as SikaTop 107 Seal Plus provide excellent adhesion and crack-bridging ability. Crystalline systems self-heal hairline cracks up to 0.4 mm, which is critical for tanks under continuous hydrostatic pressure from the surrounding water table. Always waterproof from the positive (water-contact) side for permanent results. Should I Waterproof a Basement From Inside or Outside? Waterproof from the outside (positive side) whenever the structure is accessible during construction. This places the membrane on the water-pressure side, which is more durable and prevents water from entering the concrete at all. For existing basements where external access is impossible, negative-side crystalline treatment ( MC-Special DM ) applied to the interior surface is the most effective retrofit option, as it generates crystals that block water within the concrete matrix itself.

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