Proposal confirms city of Harare water as toxic

Lack of trust in municipal water has seen a rise in the consumption of bottled and borehole water in Harare, causing plastic pollution and over-extraction of underground water. Borehole and bottled water are believed to be safe, but may actually turn out to be worse.

In 2011, the government banned 40 water brands, after they failed to meet health safety standards. And in 2017, 95% of boreholes are reported to be contaminated by an investigation by the Herald Newspaper. 2008’s Cholera epidemic started when people drank sewer contaminated boreholes in Budiriro and Glenview

There is not much literature and study on Harare’s treated quality water and authorities do not share up-to-date information with the citizens.  Political interference and corruption hinder the smooth running of affairs at the City of Harare water. Dirty, and foul-smelling water, which forms a greenish froth when boiled has been coming out of the taps in some areas. Municipal officials deny that the water is dirty and not fit for human consumption. They opt to blame the suspicious turbidity of the water on broken pipes, they claim the water picks up dirt as it passes through these broken pipes and somehow it still remains safe to drink. On whether Harare’s tap water is safe or not, officials seem to be very careful enough not to open Pandora’s box every-time that discussion is tabled. Tapsafe, an American blog whose focus is global tap water safety rankings, says Harare’s tap water is not drinkable.

A study published by Manzungu and Chioreso (2012) revealed that the City of Harare Health Department had seen an increase in samples that failed to meet World Health Organisation (WHO) standards from about 8% in 2001 to about 20% by 2005. This presents a worrying picture of the city’s tap water quality.

Cyanotoxins found in treated water

In 2019, the city of Harare engaged a South African water treatment company, Nanotech Water technologies to offer water treatment solutions for the city. The company then wrote a proposal to the City of Harare stating their findings as well as their solution and related cost and implementation timelines. It is in this proposal, which this publication is in possession of where the poor state of treated water quality was brought to the fore. The Zimbabwe Independent and the Guardian Newspapers wrote about this proposal in January 2020, they claimed it to be a report which they had seen but clearly had not gotten full possession of.

The proposal stated that “As you may be aware, the primary objective of the trial was to demonstrate the oxidative capacity of Chlorine Dioxide on the plant’s incoming and inherent algae in the plant and its associated toxins, pathogenic (disease-causing) microorganisms and other micro-contaminants.”

The plant trial results were as follows:

  1. 100% oxidation and/or removal of algae and associated toxins especially hepatotoxins (i.e. toxins that affect the liver) and neurotoxins (i.e. toxins that affect the central nervous system) by Chlorine Dioxide;
  2. 100% removal of biofilms and associated algae in the Clarifies number 8, and
  3. Consequently, the water clarity was visually and aesthetically improved

The significance of the results are as follows:

  1. Oxidation of algae, particularly filamentous algae, which is not possible with the current battery of chemicals. Chlorine Dioxide usage will lead to less Rapid Sand Filter backwashes, longer filler run times, and consequently more water produced;
  2. Removal of inherent biofilms in the Rapid Sand Filters and subsequently from the Distribution Network will lead to improved aesthetic quality of drinking water,maintenance of free residual chlorine and reduced consumption of chlorine;
  3. Oxidation of algae and its algal hepatotoxins and neurotoxins which have health effects to people and animals will lead to a significant reduction or total elimination of Powdered Activated Carbon (PAC) as confirmed by the Chartered Institute of Water and Environmental Management (CIWEM), London;
  4. Oxidation of algae will enable improved effectiveness of the main coagulant Aluminium Sulphate as this coagulant is not able to coagulate and settle live algae.

It is quite evident from the document that city officials were aware of the problems and the findings at the time,  Nanotech would not have fabricated its findings. Doing so would jeopardize its business pursuits with the city since this document was a proposal.

Health effects of Cyanotoxins

In 1996, about 50 people died in a hemodialysis facility in Brazil caused by cyanotoxin contamination of municipal water. The United States Environmental Protection Agency, states that on their website, “The acute exposure to cyanobacterial blooms and their cyanotoxins can result in a wide range of symptoms in humans, including fever, headaches, muscle, and joint pain, blisters, stomach cramps, diarrhea, vomiting, mouth ulcers, and allergic reactions. Such effects can occur within minutes to days after exposure. In severe cases, seizures, liver failure, respiratory arrest, and (rarely) death may occur. The cyanotoxins include neurotoxins (affect the nervous system), hepatotoxins (affect the liver), and dermatoxins (affect the skin). There is evidence that long-term exposure to low levels of microcystins and cylindrospermopsin may promote cell proliferation and the growth of tumors. However, more information is needed to determine the carcinogenicity of both microcystins and cylindrospermopsin.”

Possible further contaminants

Some water treatment chemicals produce disinfectant byproducts. Chlorine is one such chemical which potentially creates a by-product that causes cancer if larger if excess amounts are used to disinfect water from pathogens. Residual organic compounds (suspended or dissolved solids) may be able to pass and they react with residual chlorine to form trihalomethanes which are carcinogenic. According to a report from the U.S. Council of Environmental Quality, the cancer risk for people who drink chlorinated water is up to 93% higher than for those whose water does not contain chlorine.

Residual chlorine is very good at killing pathogens in the distribution channel. Burst water pipes allow dirty water to flow in during the rainy season or garbage to get into the water and recontaminate treated water. It is up to residual chlorine if available to kill the pathogens. Another chemical that has harmful by-products is Liquid Ammonium Sulphate (Alum). Alum operates over a limited range of pH and an increase in the amount of alum and lime to be used in the coagulation process increases the risk of levels of residual aluminum higher than permissible levels.

Monitoring and Enforcement

Regulation and standards are needed to monitor and control the number of chemicals in drinking water to acceptable levels. WHO has drinking water guidelines, and the sad thing about guidelines is that they are not an obligation, they are just a benchmark and are not legally binding.

Regulations are binding and when it comes to drinking water they are must so about ensure that they are punitive measures when set benchmarks are not followed. The United States (U.S) and the European Union (EU) have drinking water quality regulations. In America, drinking water standards enforced by the Environmental Protection Agency (EPA) specify the levels of contaminants, disinfection agents, and disinfection by-products that are allowed in drinking water.

Zimbabwe needs to work on work quality regulations and enforcement of drinking water safety standards to improve. The right to safe drinking water guaranteed in the constitution will never be fully guaranteed if action is not taken to address the issues in a transparent and accountable manner.

Source: Charles Saki*

*Charles Saki is a Bertha Fellow and  investigative Journalist. He writes in his personal capacity. Email: / Website:

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