Sewage and rainwater has seeped into people’s water tanks in the heavy monsoon spell that hit Karachi this week, leading to worries of contamination and the spread of disease. We spoke to two public health experts about solutions and risks.

In DHA, urban flooding washing into homes meant that panic spread over the dirty water getting into underground tanks.

According to Dr. Aamir Alamgir, a professor of Environmental Studies at the University of Karachi, the wastewater pollutes the water with pathogens and toxic chemicals. Harmful pathogens include E.Coli, Salmonella Typhi, and Shigella. These microorganisms can cause stomach aches, cramps, diarrhea, and in severe cases, might even cause hematochezia.

Seventy percent of Karachi’s population of 20 million is already drinking contaminated water. During the rainy season, the concentration of harmful pathogens in water becomes higher, as waste and drinking water lines mix together.

“In Karachi, the sewage lines and the drinking water lines run parallel to each other,” he said, “which causes cross-contamination. These pipes are very old, too, so during rain, when the water pressure becomes higher, these pipes burst and the drinking and wastewater get mixed up.”

That’s why stomach problems are common in rain, he continued. “Chemicals such as arsenic, lead, mercury, nickel, and chromium also sully the water. These come in through industrial waste.”

Remedies for contaminated water

The only solution for clearing out sewage water from tanks is to get it professionally cleaned, according to Dr Bashir Ahmed, the former chief engineer of the Public Health Engineering department.

“This can be done using bleaching powder, which is easily available in the market,” he said. “The powder has a high concentration of chlorine, which is the best disinfectant out there.”

There are many water tank cleaning services in the city. Professional water tank cleaners pump out water, brush the walls of the tank, and then clean them once again with water. Since they go inside the tank to clean it, it is not recommended for non-professionals to carry out the task alone.

According to Kashif of Noor Water Tank Cleaning Services, the demand for their services rises due to the rains.

“We work eight to ten hours during the rainy season,” he explained, “while on normal days, we get one to two calls only.”

However, both public health experts, Dr. Alamgir and Dr. Ahmed, emphasized that water tanks should be cleaned intermittently, even outside the raining season.

“It is recommended that to get the tanks cleaned professionally every four months, whether the sewage water seeps in or not,” Dr. Ahmed said.

Both professionals also added that precautionary measures should be taken before the rain.

“People don’t plaster their tanks properly,” Dr. Alamgir said, “and they don’t check for underground seepage either. These things increase the likelihood of water being contaminated.”

On the other hand, Dr. Ahmed suggested that people clear out underground water tanks before the monsoon hits.

“You can fill the overhead tanks, if you have any, in the meantime,” he said.

He recommended coming up with new ways to prevent the water from seeping through.

“Necessity is the mother of invention,” he said, “You can use subsoil material or mud clay to prevent water from seeping through or you can line your tanks with plaster. You’ll have to look into what solutions work in your specific context.”

Apart from professional cleaning services, the professionals also recommended that we filter water on a daily basis.

“I have a small filter machine at my house,” Dr. Ahmed admitted, “which keeps the water’s physical parameters in check. Physical parameters refer to the smell, color, texture of the water and so on.”

He also said that if one could afford it, mineral water was the safest drinking water.

“The government doesn’t own the tap water,” he said, “if it did, I would use tap water for drinking purposes too.”

On the other hand, Dr. Alamgir pointed out that using alum (pithkari) to clean the water might be useful in getting rid of ultra-fine particles in the water.

“Boiling water will also help you get rid of harmful pathogens,” he added, “but it won’t help you get rid of the toxic heavy matter in the water. In fact, the chemicals might become more harmful when heated up.”

The solution

While the aforementioned remedies are effective in alleviating some of the harmful impacts of contaminated water, state-level action is still needed to provide access to clean, safe drinking water to the residents of Karachi.

Dr. Aamir Alamgir proposed a station-to-station monitoring of water. He explained that when clean water travels from one place to another, it gets contaminated along the way.

“Sometimes, the pipes burst due to the water pressure, and sometimes, people break the pipes to steal water,” he said. “A station-to-station monitoring system will help us identify such gaps in the water lines. It will help us identify if clean water is actually reaching each station.”