Water pollution can affect people’s health. Bacterial, viral and parasitic diseases like typhoid, cholera, encephalitis, poliomyelitis, hepatitis, skin infection, and gastrointestinal diseases can spread through polluted water increasing the probabilities of overloading the capacity of excreta management systems due to diarrhoeal and vomiting cases. This impacts efficiency and capacity (that is increased amount of excreta generated due to health burdens).

In addition, proximity between water tubewells and latrines, soil porosity, ground water table, topography, drainage, and stability of slopes, may result in pollution of wells from surface water, sewage, sludge, solid waste leachates, chemical spills, etc and subsequent sickness or disease.

People who have less power in communities are usually those who are served by the worst infrastructure. Septic tank and cesspit overflows, storm spillages, and failure of sewerage networks are more likely to impact the poor and vulnerable greatest.

Soil pollution
Water pollution
Eutrophication
Loss of biodiversity and ecosystems

Water and soil pollution due to spills caused by underestimation of waste production.

Changes in the number of people using a sanitation system impact the estimated lifetime of its components. For example, if there is a sudden increase in population, elements such as pits, vaults, or tanks may fill faster than they were designed for, which may lead to spills of harmful waste into the surrounding environment.

While precipitation events may dilute the concentration of contaminants, rain can also wash septage into water bodies, wells, ecosystems, or areas of human activity, contaminating them with disease-spreading faecal coliforms.

Estimate usage and size accordingly, with intentional spare capacity.

The design of the systems should consider the likelihood of any possible future massive influx of people and any pendular effect on the sanitation systems. Sizing should also be calculated for low flows because low flows can cause sewage treatment processes to fail due to lack of nutrient loads needed for the biological process. Similarly, peak flow rates from precipitation events should be considered, and wherever possible stormwater should be separated from wastewater containing human faeces.

For the most-at-risk zones, design emergency containment structures that can safely collect and transport spills or overtopping materials to an impervious container until they can be safely managed.

In Bangladesh, there has been insufficient capacity to treat sewage and septage, and a lack of capacity to remove and treat sludge from sewage treatment facilities. This has led to much sewage being insufficiently treated and ground water pollution. This is being addressed with the gradual provision of water supply networks.

The sanitation system has been designed to minimise the likelihood of sewage overflow.

Prevention of environmental damage

Time to estimate usage and size accordingly, with intentional spare capacity.