Firle Sewerage Works is one of Harare's five treatement plants, with a capacity of 144ML/day. It is to the south west of the city, near Budiriro. 
In 2004, Harare’s water supply and sewerage/sanitation coverage amounted to over 98%, making Harare one of the cities in Africa with the highest coverage. The city's high volume of water abstraction from its main water resource, Lake Chivero, however, could no longer be sustained. The lake had been seriously polluted by large volumes of (partially) treated effluents from wastewater treatment plants in Harare and the neighbouring town of Chitungwiza. It also received pollution from agricultural, solid waste, industrial, and natural sources. Most of the wastewater treatment plants in the lake's catchment are overloaded and they experienced frequent breakdowns. This situation has been worsened by repeated years of drought, resulting in the accumulation of nitrogen and phosphorous in the lake. The negative impacts of this have been reflected in periodic fish kills, proliferation of algae and water hyacinth, and the reduction in biological diversity. 
In January 2007, Firle broke down. Of the 144 ML that flowed daily into the treatment plant, 72 ML was being discharged straight into Mukuvisi River untreated. The raw sewage did not meet the Public Health Effluent Regulations of 1972 for use as irrigation for pastures, so CoH’s farms on which cattle are reared, could not be used.
During a tour, Simon Muserere, in charge of the plant, told Willie Muringani, Zimbabwe National Water Authority (Zinwa) board chairman that $19.7 billion was urgently needed to restore the plant. Biological nutrient removal plants, inlet works, primary settling tanks, biofilters and effluent pumps as well as clarifiers, digesters and boilers were all down. Zinwa chief executive officer Engineer Albert Muyambo expressed disgust at the state of the plant.
The discharge of raw sewage into Mukuvisi is equivalent to using the river as a public toilet. The Mukuvisi is a tributary of the Manyame River, which flows into Lake Chivero, Harare's main source of water. The cost of treating polluted water with imported chemicals is quite high and Zinwa has no option but to pass it on to the consumer. The water authority is now responsible for sewerage and water management in the capital, having taken over the functions from Harare City Council. 
A 2013 paper from the World Bank, who had been approached for technical assistance to improve the operation of Harare’s water and wastewater treatment plants.
The consultants from Arup Pty were requested to identify the scope of selected urgent works projects and to prepare project design briefs that would specify the work required for each project. This policy note focusses on six of the highest priority tasks that were identified during the study. 
In March 2019, a deal was signed for US $237m, with Sinohydro Corporation to construct four new sewage treatment plants, as well as rehabilitating and extending existing plants. Sinohydro Chief Representative in Zimbabwe, Wu Yifeng confirmed the report. He said the project will increase waste water treatment capacity and quality, reduce sewage spillages and chokes, as well as reduce environment pollution and outbreaks of diseases.
The project will take place in three phases.
- One - expanding Crowborough Sewerage Works, installing supporting pipe work and constructing Lydnhurst Sewerage Works and rehabilitate existing outfall sewer.
- Two - upgrade and rehabilitate Firle Sewerage Works, and upgrade Crowborough Sewerage Works, Lake Chivero dredging and construction of a 60 ML/ day supporting pipework for the Southern Incorporated Areas.
- Three – construction of a 15 ML/ day Budiriro Sewerage Works and a 30Ml/day Gwebi Sewerage Works.
A feasibility study has already been done, before submitting a bill of quantities to council.
Harare has five sewerage treatment plants with a treatment capacity of 219.5 ML/ day but is receiving in excess of 250 ML/ day. 
In June 2019, Harare was again (still?) putting untreated sewerage into Lake Chivero, because sewerage and water treatment plants were not coping with battling with rampant illegal settlers and growing population. (in spite of this being an identified problem in 2004) 82% of untreated sewerage flows into the lake, increasing the cost of water treatment for Harare. Crowbrough Sewerage Works was pumping 82 mega litres of raw sewage into Lake Chivero on a daily basis. It receives 100 ML/ day against its installed capacity of 54 ML. On fresh water supply, it has been emphasised that Harare need about 1400 ML/ day. Of that, we have installed capacity of 600 mega litres to date.
Harare Metropolitan Provincial Affairs minister Oliver Chidawu said government and council were looking at ways to solve the problem caused by pollution in order to save lives. Chidawu, also toured Firle Sewage Works and Morton Jaffray Waterworks. There was a need for a multi-stakeholder approach to deal with the massive water and sewer reticulation problems afflicting Harare, which is in need of over $1,2 billion to deal with the sanitation disaster. Harare town clerk Hosiah Chisango said the city had a solution, but required major financing in United States dollars to ensure that the issue of water and sewer reticulation is solved. Chidawu said about $600 million was need for the reticulation and rehabilitation of the existing infrastructure and similar amount for expansion works. 
- Waste Water Management - City of Harare, City of Harare Website, Published: 12 July 2015, Retrieved: 4 April 2020
- Options for Wastewater Management in Harare, Zimbabwe, Phd dissertation, Published: 18 May 2004, Retrieved: 4 April 2020
- Major sewage treatment plant breaks down, The Herald, Published: 15 January 2007, Retrieved: 4 April 2020
- World Bank Water, World Bank, Published: October 2013, Retrieved: 4 April 2020
- Zimbabwe signs US $237m deal for four new sewage treatment plants, Construction Review Online, Published: 11 March 2019, Retrieved: 4 April 2020
- Harare pumping raw sewerage into dam, Newsday, Published: June 2019, Retrieved: 4 April 2020