Research
Is your building's water tank making your water dirty?
Often, yes. A study of 768 Dhaka households by the BRAC Institute of Governance and Development found coliform bacteria in about 80% of rooftop and underground water reservoirs. It linked the contamination to improper cleaning and maintenance, and found water at the pump stations far cleaner. The tank is the one part of the supply a building can fix itself.
What did the study find?
The BRAC Institute of Governance and Development (BIGD) tested water for its State of Cities 2018: Water Governance in Dhaka report, covering 768 households. It found:
- About 80% of rooftop and underground reservoirs had coliform bacteria.
- The highest levels were in underground reservoirs (6,000 per 100 ml) and tap water (2,000 per 100 ml) in Babu Bazar, Old Dhaka.
- Water at pump stations was much cleaner: only about 20% of samples were contaminated.
- The researchers pointed to improper cleaning and maintenance of reservoirs. They also noted that suction pumps can pull mud and other contaminants into the water.
What does that mean for your building?
Water can leave the supply cleaner than it reaches your tap. Between the two it sits in your building's underground reservoir and overhead tank, and those are the owner's responsibility. A tank that is never cleaned collects sludge, and a cracked or badly covered one can let dirty water in.
What are the warning signs?
- A smell, a colour, or grit in the water from the tap
- Sludge or slime on the tank floor and walls when you open it
- A loose, broken or missing lid, or insects inside
- Cracks in an underground reservoir, especially one close to a drain or septic tank
- A long time since the last cleaning, or no one who remembers when it was
What does a proper clean involve?
It is more than emptying the tank and splashing it with water. A proper clean drains the tank, removes the sludge, scrubs the walls and floor, disinfects, rinses and refills. It also includes checking the lid, the cracks and the inlet pipes, and giving you a written report with before and after photos. You should know what was found and what needs fixing, not just that "the tank was washed".
Our water tank cleaning service is priced per CFT of tank volume, with the steps written down and the report sent to you on WhatsApp.
This article summarises published research in plain language. It is not a water-quality test. If you are worried about your water, have it tested by an accredited laboratory.