Water tank cleaning matters in Karachi because almost every drop a household uses has first sat in a tank, and stored water gets dirtier with time. A dirty tank exposes a family to typhoid, hepatitis, diarrhoea and skin infections through drinking, cooking, bathing and ablution. Cleaning and disinfecting the tank every 6 months removes the sludge and film where those germs live.
This article looks at the health and hygiene side of tank cleaning: how contamination reaches people, what Pakistan’s drinking water standards require, and what a cleaning does and does not fix.
The Need for Clean Water in Karachi
Karachi’s water has been tested many times, and the results are consistent. In 2017 the Pakistan Council of Research in Water Resources (PCRWR) tested 118 samples from across the city for a Sindh High Court judicial commission. It found 107 of them unsafe to drink. Coliform bacteria were above WHO limits in 88% of samples, and a third contained E. coli from faecal contamination (Dialogue Earth). The research officer leading the study said the E. coli pointed to sewage mixing with drinking water lines.
UNICEF estimates that 70% of households in Pakistan drink bacterially contaminated water, and that 53,000 Pakistani children under five die every year from diarrhoea linked to poor water and sanitation (UNICEF Pakistan).
A household cannot repair the city’s pipes. It can control the two places where its own water sits for days: the underground tank and the overhead tank.
Understanding Water Tanks
A typical Karachi house has an underground concrete tank that receives line or tanker water, a pump, and an overhead plastic, fibre or concrete tank that feeds the taps by gravity. Flats share larger versions of the same arrangement. If you want the background on designs and materials, see types of water storage tanks.
Three things happen in any tank over time:
- Sediment settles. Silt, sand and rust from the supply sink to the floor and form sludge.
- Biofilm grows. Bacteria attach to the walls and build a slippery film that protects them from chlorine.
- Things get in. Dust, insects, lizards, bird droppings and, in underground tanks, seepage from nearby drains.
None of this is visible at the tap until it is well advanced. Water can look clear and still carry enough bacteria to make a child ill.
Health Implications of Unclean Water Tanks
Through drinking and cooking
The main waterborne infections in Karachi spread when sewage reaches drinking water:
- Typhoid. An extensively drug-resistant strain has circulated in Sindh since late 2016. Of 5,274 such cases recorded by December 2018, 69% were in Karachi (WHO).
- Hepatitis A and E. Both spread through contaminated water. Hepatitis E is especially dangerous in pregnancy: up to 20–25% of women who catch it in the third trimester can die (WHO).
- Cholera. Sindh reported 234 laboratory-confirmed cases between January and May 2022 (WHO).
- Diarrhoea and dysentery from E. coli, Shigella, rotavirus and parasites such as Giardia.
Boiling kills most of these germs, and every family should boil or filter drinking water. Boiling does not help with the water used to wash salad, rinse dishes or brush teeth. We cover each illness in waterborne diseases common in Karachi.
Through bathing and ablution
Tank water touches skin, eyes, ears and the inside of the nose every day. Dirty water can cause skin rashes, eye and ear infections and infected cuts. The most serious risk is Naegleria fowleri, which causes a brain infection that is almost always fatal. It infects only when water goes up the nose, and you cannot catch it by swallowing water (CDC). Karachi reports deaths most summers, and health officials link them to water that is not filtered or chlorinated (Dawn).
Through breathing
Showers and taps turn water into fine spray. Legionella bacteria grow in warm, stagnant water and infect the lungs when that spray is inhaled. Read more in Legionella in Karachi’s water tanks.
Who is most at risk
Babies and young children, pregnant women, older people, and anyone with diabetes, kidney disease or a weakened immune system. They get sick from smaller doses and recover more slowly. Our article on dirty tanks and children’s health goes into this.
The Role of Water Tank Cleaning
Cleaning breaks the chain at the storage stage. It does three things that no filter, tablet or boiling pot can do:
- Removes the sludge. The layer on the floor is the food supply and the hiding place for bacteria.
- Strips the biofilm. Pressure washing and scrubbing take the film off the walls. Chlorine alone cannot get through it.
- Disinfects bare surfaces. Once the tank is physically clean, a chlorine solution kills what is left.
It also puts a trained person inside the tank twice a year. Cracks, broken lids, missing mesh and corroded fittings are noticed long before they would be from outside.
What cleaning cannot do is change the water that arrives afterwards. If the line or the tanker delivers dirty water, the tank will receive it. Cleaning means that water lands in a disinfected tank and is used up within days, instead of feeding months of growth. For the wider picture of how bacteria behave in tanks, see bacteria in Karachi’s water tanks and how to combat them.
Benefits of Regular Water Tank Cleaning
Beyond health, a clean tank gives clear, odourless water, protects the pump and filters from grit, and extends the life of the tank itself. These are set out in the benefits of regular water tank cleaning. The opposite case is described in the dangers of neglecting tank cleaning.
Hygiene Habits That Support a Clean Tank
- Keep tank lids shut and sealed, and cover vents and overflow pipes with mesh.
- Never dip buckets or hands into the tank. Draw water through the tap or pump.
- Keep the area around the underground cover dry and free of rubbish, and keep animals away from it.
- Store drinking water in a clean, covered container and wash that container daily.
- Boil or filter water for drinking, baby formula and brushing children’s teeth.
- For ablution and nasal rinsing during the hot months, use boiled and cooled water if you are unsure of the tank.
Water Tank Cleaning Process
The process we follow has six steps: drain, remove sludge, pressure-wash, vacuum out the waste water, disinfect, and rinse. A standard house takes 2 to 4 hours. Details are on the service procedure page, and the disinfectants are listed under cleaning chemicals.
We recommend this every 6 months for homes, and more often for tanker-fed houses and shared buildings. The reasoning is in how often you should clean your water tank.
Regulations and Guidelines in Karachi
Pakistan’s National Standards for Drinking Water Quality, notified by the Pakistan Environmental Protection Agency in 2010, set the benchmarks that drinking water should meet (S.R.O. 1063(I)/2010):
| Parameter | National standard |
|---|---|
| E. coli and total coliforms | Must not be detectable in any 100 ml sample |
| Turbidity | Below 5 NTU |
| Total dissolved solids (TDS) | Below 1,000 mg/L |
| pH | 6.5 to 8.5 |
| Residual chlorine | 0.2 to 0.5 mg/L at the consumer end |
| Taste and odour | Not objectionable |
These standards apply to the water supplied. We are not aware of any rule that tells a household how often to clean its own tank, and the WHO’s technical note on cleaning and disinfecting water storage tanks describes the method without setting an interval. In practice the responsibility sits with the owner. For shared buildings, see who is responsible for tank cleaning in apartment buildings, and for the legal background, government regulations on water quality in Karachi.
Factories, food businesses, hospitals and schools usually have their own audit or inspection requirements. We give commercial and industrial clients a cleaning certificate and a tax invoice for those records. Some of the organisations we have worked for are listed on our clients page.
Raising Awareness and Community Initiatives
The tanks that are cleaned least are the ones everybody uses and nobody owns: mosques, schools, madrasas, clinics and apartment blocks. A mosque tank supplies ablution water to hundreds of people a day. A school tank supplies children who drink straight from the tap.
If you sit on a mosque committee, a school board or a residents’ union, three steps make a real difference:
- Put tank cleaning on the calendar twice a year and record each date where people can see it.
- Name one person who is responsible for lids, mesh and monthly checks.
- Budget for it. The cost per user is tiny.
Frequently Asked Questions
Can clear water still be unsafe?
Yes. Bacteria and viruses are invisible, and water has to be heavily contaminated before it changes colour or smell. Clear water from a tank that has not been cleaned in years should not be trusted.
If I boil my drinking water, do I still need to clean the tank?
Yes. Boiling protects only the water you boil. Bathing, washing, cooking prep and ablution all use water straight from the tank.
Is the chlorine used in cleaning safe?
Yes, when it is used correctly. Chlorine is the standard disinfectant for drinking water worldwide. We apply it after scrubbing, leave it for the contact time, and rinse the tank before it refills.
Can I test my water?
Yes. A laboratory test for E. coli and total coliforms is the most useful one for a household. Take the sample from a kitchen tap in a sterile bottle from the lab.
Protect Your Household’s Water
If you do not know when your tank was last cleaned, assume it is overdue. Call or WhatsApp 0313-2796778, see rates on our charges page, or send a message through the contact page. Our teams work in every part of the city, from Liaquatabad and Nazimabad to Saddar.
About the author: Ahmar Shoaib is the founder of Karachi Tank Cleaning. He holds a BS in Chemical Engineering from Karachi University and has run the company’s cleaning and disinfection work since 2007. This article follows our editorial policy.
Sources: PCRWR water testing for the Sindh High Court judicial commission (2017), reported by Dialogue Earth; UNICEF Pakistan, WASH programme page; WHO Disease Outbreak News on typhoid (December 2018) and cholera (June 2022) in Pakistan; WHO fact sheet on hepatitis E; CDC, About Naegleria fowleri infection; National Standards for Drinking Water Quality, S.R.O. 1063(I)/2010; WHO Technical Note No. 3 (2013).
