Swimming pools and intra-city climates: Influences on residential water consumption in Cape Town

Abstract

Water demand management can be effective as a resource management approach if demand estimation is accurate and consumption determinants are defined. While determinants such as household income, regional climate, water price, property size and household occupancy have been comprehensively studied and modelled, other determinants such as swimming pools and intra-city climates have not. This study examines residential water consumption in the City of Cape Town in 2008/2009, under property size regimes, to separately determine whether the presence of pools or occurrence of different intra-city precipitation patterns have an influence on water consumption. A sample of 14 233 properties is analysed, with 20.86% having swimming pools within their boundaries. Overall, those properties with swimming pools used 37.36% or 8.85 kℓ per month more water than those without, with pools having a larger influence on household consumption on smaller properties. These results were statistically significant. Different precipitation patterns occurred over the study period, and while there were indications that consumption may be lower if there is more rainfall, limited evidence was found to support the hypothesis.

Mitigating the impact of swimming pools on domestic water demand

“…When all property areas are lumped together, the impact of a swimming pool is an average increase of 8.2 kℓ/month or 30% -which is similar to that reported by Siebrits (2012). However, the significant differences between the various bands suggest that other factors are impacting the water demand, apart from -but linked to -the swimming pool.…”

How different Cape Town residential suburbs helped avert Day Zero

“…Studies confirm that the main variables that determine residential water use are household income, property/stand size, property price, number of occupants in a dwelling or household, as well as the cost of water (Duke et al 2002;van Zyl et al 2007;Siebrits 2012). The informal settlement of Dunoon was initially selected as one of the 11 suburbs, however, on further investigation it was determined that there was no discrete bulk water meter data to accurately represent the informal service delivery in this settlement, with the only available data being for formal houses, businesses and industries.…”

“…Studies have confirmed that an integrated approach that makes use of incentives and communication, together with regulatory measures, is more effective in encouraging water conservation practices than tariffs and restrictions alone (Renwick & Archibald 1998;Savenjie & van der Zaag 2002;Siebrits 2012). For example, water restrictions and rationing are effective in reducing demand, but result in a need for cost recovery following a crisis, and consequently increasing the water rates for all water users regardless of their behaviour during the drought (Duke et al 2002).…”

“…Water demand patterns vary significantly with the level of income of households. It is widely known that socio-economic variables, namely property size, property price, household income, and household size, have a significant effect on household water use (Duke et al 2002;Jansen & Schulz 2006;van Zyl et al 2007;Siebrits 2012). This is particularly pertinent in a socio-economically unequal city, such as Cape Town, where WC/WDM behaviours are constrained because a large portion of households already operate at threshold levels.…”

“…if the collective household income is R4,500 or less per month and the market value of the property is less than R300,000. The CoCT relies on cross-subsidisation that is built into its stepped block tariff structure whereby large volume users support the free basic water (FBW) allocation for indigent households (Savenjie & van der Zaag 2002;Jansen & Schulz 2006;Siebrits 2012;CoCT 2018a). WDM is hence a multifaceted approach comprising technological innovation to reduce household water use while also meeting social inequalities and the needs of poor households.…”