Globally, over 80% of all wastewater is discharged without treatment. This report of the UN World Water Assessment Programme assesses the problem of wastewater per sector and per region. We recommend chapter 9 on Regional Aspects, Africa, and chapter 16 on Water Reuse and Cost Recovery, and chapter 17 on Knowledge, Innovation, Research and Capacity Development.

Abstract from the Executive Summary: regional perspectives (Africa)
"One of the main challenges related to wastewater in Africa is the overall lack of infrastructure for collection and treatment, which results in the pollution of often-limited surface and groundwater resources. African cities are growing quickly, and their current water management systems cannot keep up with the growing demand. However, this situation provides opportunities from improved urban wastewater management using multi-purpose technologies for water reuse and the recovery of useful by-products. Strong advocacy is needed to convince policy-makers of the phenomenal ‘cost of inaction’ in terms of socio-economic development, environmental quality and human health."

Abstract from the Executive Summary: Cost recovery and appropriate financing mechanisms
"Decentralized wastewater treatment systems can be used to offset some financial problems generated by centralized systems. When properly designed and implemented, such low-cost technologies can provide satisfactory results in terms of effluent quality, although they too require an appropriate level of operation and maintenance in order to avoid system failure.

Wastewater use can add new revenue streams to wastewater treatment, particularly under conditions of recurring or chronic water scarcity. Several different business models have been implemented where cost and value recovery offer a significant advantage from a financial perspective. However, revenues from the sale of treated wastewater alone are not generally adequate to cover the operational and maintenance costs of the water treatment facility itself. The recovery of nutrients (mainly phosphorus and nitrogen) and energy can add significant new value streams to improve the proposition of cost recovery.

Although revenues from wastewater use and resource recovery may not always cover their extra costs, the benefits from investments in water reuse may compare well with the cost of dams, desalination, inter-basin transfers, and other options to increase water availability."