Quick answer
To repair a leaking concrete water tank, empty and clean it, repair cracks and honeycombed concrete, then apply a cementitious waterproofing slurry to the inside. For water-retaining structures SikaSeal-105 is applied at 3.0–6.0 kg/m² in total, in a minimum of two coats; Sikadur-31 CF Slow epoxy repairs damaged concrete before coating. For drinking-water tanks, confirm the product's potable-water suitability on the current Sika datasheet before use.
Common causes
- Cracks in the tank walls or floor from shrinkage or settlement
- Honeycombed concrete and leaking construction joints
- Leaks around inlet, outlet and overflow pipes
- No internal waterproofing when the tank was built
Step-by-step
- 1
Empty, clean and dry-inspect
Empty the tank, scrub off algae and loose material, and mark every crack, joint and damp patch.
- 2
Repair the concrete
Cut out honeycombed or broken concrete and rebuild it; Sikadur-31 CF Slow is an epoxy repair mortar suited to hot conditions. Seal around pipe penetrations.
- 3
Pre-wet
Saturate the concrete surface with water, leaving no standing water.
- 4
Apply the waterproofing
Brush on SikaSeal-105 at 3.0–6.0 kg/m² in total over at least two coats, or SikaTop-107 Seal in two coats, paying extra attention to corners and joints.
- 5
Cure before filling
Keep the coating moist-cured and wait the full curing time on the datasheet before refilling, then flush the tank before use.
Always follow the current Sika Pakistan product datasheet for surface preparation, temperatures and curing.
Products for this job
SikaSeal-105 PKCementitious slurry rated for water-retaining structures (3.0–6.0 kg/m²).From Rs. 3,700
SikaTop-107 Seal PKFlexible two-component waterproofing slurry.From Rs. 8,000
Sikadur-31 CF SlowEpoxy repair mortar for damaged concrete, made for hot climates.From Rs. 3,400
SikaGrout-114 PKNon-shrink grout for filling voids around pipes and repairs.From Rs. 2,999
SikaLatex PKBonding agent for repair mortars.From Rs. 5,300
Frequently asked questions
Which chemical is best for water tank leakage repair?
For concrete tanks, a cementitious waterproofing slurry applied inside the tank — SikaSeal-105 is specified for water-retaining structures at 3.0–6.0 kg/m² in at least two coats. Cracks and damaged concrete are repaired first, for example with Sikadur-31 CF Slow.
Can I use waterproofing in a drinking water tank?
Only if the current Sika datasheet for that product states it is suitable for contact with potable water. Ask us on WhatsApp and we will check the datasheet for you before you buy.
Tanki ki leakage kaise band karein?
Tanki khaali karke saaf karein, cracks aur pipe ke joints repair karein, phir andar SikaSeal-105 ya SikaTop-107 Seal ke kam az kam do coat lagayein aur poori curing ke baad hi paani bharein.