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Accueil du site → Doctorat → Afrique du Sud → 2022 → An investigation into untreated greywater as supplementary household water source to augment potable municipal supply with consideration of associated risks.

Stellenbosch University (2022)

An investigation into untreated greywater as supplementary household water source to augment potable municipal supply with consideration of associated risks.

Nel, Nicole

Titre : An investigation into untreated greywater as supplementary household water source to augment potable municipal supply with consideration of associated risks.

Auteur : Nel, Nicole

Université de soutenance : Stellenbosch University

Grade : Doctor of Philosophy (PhD) 2022

Résumé partiel
Despite the available body of research regarding supplementary household water sources and in particular, greywater use, there is a critical gap when it comes to understanding the uptake of untreated greywater in suburban areas and the trade-off between the risks and potential water savings. This dissertation focuses on untreated greywater use in residential, fully serviced houses equipped with regular water use appliances and with conventional waterborne sewers. The main objective is to gain an improved understanding of the uptake of untreated greywater and the potential for use and application in suburban areas by exploring the trade-off between expected water savings (associated with quantity) and potential risks (associated with quality) as related to untreated greywater use. This study starts with addressing on-site supplementary household water sources with a focus on groundwater abstraction, rainwater harvesting, and greywater use as available non-potable supplementary water sources to residential consumers. The legal position in South Africa and an end use model to assess the theoretical impact of these sources on water demand in formal residential areas, is presented. The model provides valuable strategic direction and indicates a significant theoretical reduction in potable municipal water demand of between 55% and 69% for relatively large properties with irrigated gardens when supplementary household sources are maximally utilised (when compared to exclusive municipal use as a baseline). This load reduction on piped reticulation systems could be an advantage through augmenting municipal supply. However, water service planning and demand management are complicated by the introduction, and possible future decommissioning, of any household water source. The trade off between the advantages and disadvantages of this load reduction defines whether there is a nett positive benefit linked to the use of the household water sources. Groundwater is the household water source considered to have the most notable penetration and intensity to impact potable water demand in residential areas and is coupled to a relatively low risk in terms of water quality relative to other uses such as greywater use. Groundwater, however, has the biggest barrier to entry and requires the highest capital investment of the three supplementary household water sources. The distinct trade off between the advantages and disadvantages of untreated greywater, particularly in comparison to the other supplementary household water sources, provides justification towards it being the focus of this study. Untreated greywater use at household level is an accessible water source to supplement non-potable water requirements in times of emergency water curtailments, but poses various risks to the consumer, the wider community, infrastructure and the environment.

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Page publiée le 11 janvier 2023