Underground Water Tank Cleaning in Karachi
Pest Tech cleans underground water tanks (RCC sumps) across Karachi. A trained crew isolates the pump, drains the sump, removes the sludge layer, scrubs and pressure-washes the walls and floor, chlorinates for the full contact time and checks the residual. Underground tanks collect the heaviest silt from line and tanker water, so they need cleaning first.
Estimated starting price — final price confirmed after free inspection: from Rs 3,500 per tank.
Signs your underground tank needs cleaning
The underground sump is where line water and tanker water arrive first, so it is where sand, silt and organic matter settle. Signs it needs cleaning:
- A visible layer of sludge or sand on the floor when the level is low
- Brown or cloudy water after the pump runs
- Grit in the overhead tank and in taps soon after it was cleaned
- A musty or rotten smell from the manhole
- Cracks, seepage marks or damp patches around the sump
- Heavy tanker use or monsoon flooding near the house
How we clean an underground tank
- 01
Survey and safety check
We check access, the manhole cover, the pump and float valve, and ventilate the sump before anyone enters.
- 02
Isolate and drain
The pump is switched off and isolated, and usable water is pumped out or transferred.
- 03
Sludge removal
Silt and sludge are removed by hand and with a submersible pump, and taken away for proper disposal.
- 04
Scrub and pressure-wash
Walls, floor and the underside of the roof slab are scrubbed and pressure-washed to remove biofilm.
- 05
Chlorinate, rinse and refill
A measured chlorine solution is applied for the full contact time, rinsed out, and the residual is checked after refilling.
Why underground sumps get so dirty
Underground RCC tanks fill first, so everything heavy in the incoming water settles on their floor. Line water after a supply gap carries silt and rust; tanker water often carries sand and organic matter of unknown origin. Older sumps can also take in seepage through cracks, which is the main contamination risk during the monsoon.
| Problem | Cause | What we do |
|---|---|---|
| Sludge layer | Silt and sand from line and tanker water | Manual and pump removal |
| Biofilm on walls | Bacteria growing on wet concrete | Scrubbing and pressure-washing |
| Bad smell | Rotting organic sediment | Full desludging and chlorination |
| Seepage stains | Cracks in older RCC | Report the cracks so they can be repaired |
Tanker-dependent homes should let tanker water settle before pumping it to the roof, and clean the sump every three to four months.
Confined-space safety
An underground tank is a confined space. Air inside can be low in oxygen or hold fumes, and the opening is small. Our crew ventilates the tank before entry, keeps a person outside at all times and uses safety gear. Please never send a household helper, guard or untrained worker into a sump — and never add chemicals to a tank yourself. The US Occupational Safety and Health Administration explains why confined spaces need trained entry.
Clean the overhead tank in the same visit — see overhead tank cleaning — or the sludge from the sump will reach it again. The main water tank cleaning service page covers both, and the cost calculator estimates the price by gallons.
Buildings and large sumps
Apartment buildings in Gulshan-e-Iqbal, Gulistan-e-Johar and North Nazimabad often have one large shared sump. We plan the job with the union so residents get notice, the sump is cleaned and refilled the same day where possible, and the rooftop tanks are done straight after. Factories in Korangi and SITE are scheduled outside production hours.
Confined-space safety and hygiene
- Only our trained crew enters the sump, after ventilation and with a person stationed outside throughout.
- The pump is isolated so no dirty water reaches the overhead tank or house lines.
- Chlorine is measured for the tank volume and rinsed out after the contact time; the residual is checked before use.
- Sludge is removed from the property, not washed into drains next to the tank.
Underground tank cleaning price in Karachi (2026)
Underground tank cleaning is priced per tank by capacity in gallons, with heavy sludge and large building sumps adjusted after inspection. Cleaning the overhead tank in the same visit lowers the combined price.
| Tank size | Estimated price (PKR) |
|---|---|
| Underground RCC — up to 1,000 gal | Rs 3,500 |
| Underground RCC — 1,001 gal–2,000 gal | Rs 4,500 |
| Underground RCC — 2,001 gal–3,000 gal | Rs 5,500 |
| Underground RCC — 3,001 gal–5,000 gal | Rs 7,500 |
| Each extra 1,000 gal above 5,000 gal | +Rs 1,200 |
Every figure is an estimate until a free inspection confirms the scope of work.
Why Karachi chooses Pest Tech for underground tank cleaning
Our crews have worked in Karachi bungalows, apartment buildings and factories since 2005, and we follow a fixed seven-step sequence so no sump is refilled before it is properly cleaned and disinfected.
Trusted by Khalid Foods, Beaconhouse School System, Dunkin' Donuts — plus thousands of Karachi homes.
Underground Tank Cleaning across Karachi
We treat every district of Karachi from our base in Operative Housing Society. Popular areas:
Related guides
Related services
- Water Tank Cleaning — Underground and overhead tanks cleaned, desludged and chlorinated.
- Overhead Tank Cleaning — Rooftop plastic, fibre and cement tanks cleaned and chlorinated.
- Tank Disinfection & Chlorination — Measured chlorination after cleaning, floods or for new tanks.
Underground Tank Cleaning: frequently asked questions
Any visible layer is worth removing. Tanker-fed sumps build up sediment fastest and usually need cleaning every three to four months.
Please do not send untrained staff into an underground tank. It is a confined space and must only be entered by a trained crew with ventilation and safety gear.
For a typical house the job is done in one visit and the tank is refilled the same day. Large building sumps are scheduled with management.
We show you the cracks and seepage points so they can be repaired, because seepage can let ground water — sometimes sewage — into the tank.
Book underground tank cleaning in Karachi
Send your area and a photo of the problem — we reply with the next free inspection slot.
Mon–Sat, 9:00 AM – 7:00 PM · Free inspection · Re-treatment at no extra cost if pests return