Wellcool provides dependable underground water tank waterproofing services in Pakistan for homes, plazas, housing societies, schools and factories. We stop clean water leaking out into the soil and, just as importantly, stop dirty groundwater and sewage seepage getting in, using pressure-resistant linings suited to drinking water storage.
★★★★★ Trusted by homeowners & businesses across Pakistan
Stops leaks out and contamination in
Products selected for drinking water contact
Inspection before any work begins
Underground water tanks are the backbone of water storage in Pakistani buildings. Municipal lines from WASA and housing society networks fill these tanks at irregular hours, and a motor then lifts water to the overhead tank. Because the tank is buried, it is out of sight and often ignored for years. Meanwhile, it sits in soil that can be wet, salty or contaminated, often only a few feet from a septic tank, sewer line or soakage pit. When the walls, floor or joints develop cracks, two problems arise. First, clean water leaks into the ground, wasting supply and raising bills where water is purchased by tanker. Second, and more serious, polluted groundwater and sewage seepage can enter the tank, contaminating the water your family drinks and bathes with.
Wellcool offers complete underground water tank waterproofing in Pakistan, focused on keeping water in and contaminants out. We empty and clean the tank, inspect the walls, floor, roof slab, manhole and pipe entries, repair cracks and joints, and apply a pressure-resistant internal lining suitable for potable water. Where the tank lies near drains or in a high water table area, we pay particular attention to joints and openings that could allow seepage inward.
Underground tanks face pressure from two directions. When full, water presses outwards against the walls and floor. When the level drops, groundwater and soil moisture press inwards, especially in the monsoon when the water table rises in Lahore, Gujranwala, Sialkot, Faisalabad and low-lying parts of Peshawar and Rawalpindi. Concrete or brick tanks that were not designed and built to be watertight cannot resist this constant two-way pressure. Many older tanks were built in brick masonry with cement plaster, which develops cracks and becomes porous over the years.
The roof slab and manhole are frequent sources of contamination. Tanks are often built under driveways, garages or lawns, and rainwater, washing water or garden water can run straight in through cracked roof slabs and loose manhole frames. Pipe entries for the inlet, suction and wash-out are usually sealed with ordinary mortar that separates over time. In older neighbourhoods, sewage lines and septic tanks are sometimes close to water tanks, and leaking sewers saturate the surrounding soil. Any defect in the tank then becomes a pathway for contaminated water to enter.
Because the tank is hidden, look for these indirect signs:
Water contamination is a widespread concern in Pakistan, and a damaged underground tank is one of the ways it reaches homes. If sewage or polluted groundwater enters the tank, bacteria and other contaminants can spread through every tap in the house. Even if you use filters for drinking water, the same water is used for cooking, washing dishes, bathing and brushing teeth. A tank that rises during rain or turns cloudy after a storm is a strong warning that outside water is getting in. Waterproofing the tank properly, together with sealing the manhole and roof slab, is a practical step to protect your family’s health. We also recommend periodic water testing by a qualified laboratory, especially after repairs.
Walls, floor, roof slab, manhole and pipes checked
Linings that resist inward and outward pressure
Internal linings selected for drinking water
Ventilation and safety precautions inside tanks
Crystalline slurry is ideal for underground RCC tanks because it works against water pressure from either side. Applied to saturated, prepared concrete, it forms crystals deep in the pores and fine cracks, making the tank walls and floor dense and watertight. It does not form a film that can peel when groundwater pushes from behind.
Older brick masonry tanks need a strong bonded lining. After removing weak plaster, we apply a waterproof render or base coat followed by a flexible cementitious waterproofing membrane in multiple coats, with reinforcement mesh at corners and the wall-floor junction. The lining is suited for potable water when the product is certified for it.
If groundwater is visibly running into an empty tank through a crack or joint, it must be stopped before lining. We inject polyurethane or acrylic resin through packers to seal the flow from within the wall, then complete the lining over the sealed area.
Inlet, suction, overflow and wash-out pipes pass through the tank wall. We cut out loose mortar, rebuild the opening with non-shrink waterproof grout, add a flexible sealant collar and wrap the lining around each pipe so there is no gap for seepage.
The top of the tank is often the main entry for dirty surface water. We repair cracks in the roof slab, waterproof its upper surface where accessible, and raise and seal the manhole frame above the surrounding floor level with a tight-fitting cover so washing water and rain cannot flow in.
Sharp internal corners are formed into rounded coves with waterproof mortar, and the floor is treated with extra attention because it carries the greatest water pressure and collects sediment. A smooth, well-coved interior is also easier to clean.
Check tank, manhole, pipes and nearby sewer lines
Pump out, remove sludge and wash all surfaces
Ensure safe air before and during work inside
Remove weak plaster, stop inflow, fix cracks and pipes
Pressure-resistant system with coves and reinforcement
Cure, wash out and refill with level monitoring
Newer houses and plazas usually have RCC underground tanks, while many older homes and smaller buildings have tanks built in brick masonry with plaster. RCC tanks generally respond very well to crystalline treatment combined with joint and pipe detailing. Brick tanks have many more joints and are more porous, so they need a strong bonded lining over a sound base coat. Where a brick tank is badly cracked or the walls are bulging inward from soil pressure, waterproofing alone may not be enough, and we will advise you to consult a structural engineer about strengthening or rebuilding.
We give a written quote after inspecting the tank. The main cost factors are:
Call or WhatsApp 0321-4156036 to book an underground tank inspection. Send photos of the tank interior or manhole on WhatsApp for an initial opinion.
If you are building a new house, the location and detailing of the underground tank matter as much as the waterproofing. Keep the tank as far as possible from septic tanks, soakage pits and sewer lines. Raise the manhole above the finished floor level so washing water cannot run into it. Use a properly designed RCC tank rather than a thin brick tank, include waterstops in construction joints, and use puddle flanges for pipes cast into the walls. Waterproofing applied during construction, both inside and on the outside face before backfilling, gives the best long-term protection. We can advise your contractor at the design stage.
Housing societies, apartment complexes, factories, schools and hospitals often have large underground reservoirs with multiple chambers. These serve many people, so a leak or contamination problem has a wide impact. We plan the work chamber by chamber where possible, so supply continues while one section is treated. Safety measures for working in confined spaces, such as ventilation, lighting and supervision, are part of our process on every tank, large or small.
For tanks on the roof, see water tank waterproofing. Underground tanks are often next to basements, so read about basement waterproofing. You may also need leakage and seepage treatment, crack filling and repair or dampness and seepage solutions for nearby walls.
In many Pakistani homes the underground tank is built beneath the car porch or driveway to save space. This means the roof slab of the tank carries the weight of vehicles, and every time the car is washed, soapy water, oil and dirt flow across the slab and towards the manhole. Over time, cracks develop in the slab and the joint around the manhole frame loosens. We check the roof slab carefully in these locations, repair cracks with suitable repair mortar, seal the manhole frame and, where possible, raise it slightly above the floor and slope the surrounding area away from the opening. Simple changes like this make a large difference in preventing contamination.
Leaks out of the tank are easy to miss because the water disappears into the ground. A practical check is to fill the tank, switch off both the supply valve and the motor, mark the water level and check it after several hours. A noticeable drop without any usage indicates outward leakage, either through the structure or a pipe joint. In some homes the leaked water also shows up as dampness on the lower part of nearby walls or in the basement. Finding and stopping this loss reduces wasted supply and protects foundations from repeated wetting.
Every Wellcool customer receives the same complete service — from the first inspection to the final check. No shortcuts, no half-finished work.
Walls, floor, roof slab, manhole and pipes
Tank emptied, scrubbed and washed
Injection where groundwater is entering
Entries rebuilt and manhole protected
Pressure-resistant, potable-suitable system
Washout and level monitoring after refilling
Your building is our priority. From the first phone call to the final check, our team treats your property as if it were our own. We arrive on time, protect your home while we work, and leave the site clean.
We follow one simple rule: prepare properly, apply correctly, check thoroughly. That is how results last for years — not just for one season.
Punjab, KPK & Islamabad
Site survey & quote
Tested systems
Clear timelines
If the tank level rises without supply during the monsoon, groundwater or surface water is entering through cracks, joints, pipe entries or the manhole. This also means the water may be contaminated. The tank should be inspected, cleaned and waterproofed, and the manhole raised and sealed to stop surface water flowing in.
Yes, when suitable products are used. We use internal linings that manufacturers state are suitable for potable water contact, follow curing times and wash out the tank before refilling. We avoid bitumen, solvent paints and other coatings unsuitable for drinking water storage.
Most brick tanks can be waterproofed by removing weak plaster and applying a strong bonded lining with reinforced corners. If the walls are severely cracked, bulging or unstable, waterproofing alone will not fix the structural issue, and we will recommend consulting a structural engineer.
A typical household underground tank takes a few days, including emptying, cleaning, repairs, lining and curing. Larger and multi-chamber tanks take longer. We share the schedule in advance so you can arrange temporary water storage or supply.
A bad smell can come from sludge, algae or contamination entering the tank. Cleaning removes sludge, and waterproofing with manhole sealing stops outside water getting in. If a nearby sewer is leaking, it should be repaired too. Testing the water after treatment is recommended.
Yes. Underground tanks are confined spaces. We ventilate the tank, use proper lighting, keep a team member outside at all times and limit time inside. Safety is part of our standard process on every tank.
On existing tanks the outside is usually inaccessible, so we treat from inside with systems that resist pressure from behind. During new construction, we recommend waterproofing the outside face as well before backfilling.
Complete waterproofing for every part of your building, from roof to foundation.
Seamless protection for flat RCC roofs
Stop leaks under tiles and floors
Keep below-ground floors dry
Protect open slabs over living rooms
Safe lining for overhead tanks
Stop water loss from pools
Find and fix hidden leaks
Seal structural and surface cracks
Tell us your city and the problem, send a few photos on WhatsApp, and our team will arrange a site visit. No obligation, no hidden cost.
Call, WhatsApp or fill in our quote form for a free estimate.